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322 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Christian Brauner
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07422c948f
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eventpoll: drop vestigial epi->dying flag
With ep_remove() now pinning @file via epi_fget() across the f_ep clear and hlist_del_rcu(), the dying flag no longer orchestrates anything: it was set in eventpoll_release_file() (which only runs from __fput(), i.e. after @file's refcount has reached zero) and read in __ep_remove() / ep_remove() as a cheap bail before attempting the same synchronization epi_fget() now provides unconditionally. The implication is simple: epi->dying == true always coincides with file_ref_get(&file->f_ref) == false, because __fput() is reachable only once the refcount hits zero and the refcount is monotone in that state. The READ_ONCE(epi->dying) in ep_remove() therefore selects exactly the same callers that epi_fget() would reject, just one atomic cheaper. That's not worth a struct field, a second coordination mechanism, and the comments on both. Refresh the eventpoll_release_file() comment to describe what actually makes the path race-free now (the pin in ep_remove()). No functional change: the correctness argument is unchanged, only the mechanism is now a single one instead of two. Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-10-2470f9eec0f5@kernel.org Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> |
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Christian Brauner
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3a4551ea9c
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eventpoll: drop dead bool return from ep_remove_epi()
ep_remove_epi() always returns true -- the "can be disposed"
answer was meaningful back when the dying-check lived inside the
pre-split __ep_remove(), but after that check moved to ep_remove()
the return value is just noise. Both callers gate on it
unconditionally:
if (ep_remove_epi(ep, epi))
WARN_ON_ONCE(ep_refcount_dec_and_test(ep));
dispose = ep_remove_epi(ep, epi);
...
if (dispose && ep_refcount_dec_and_test(ep))
ep_free(ep);
Make ep_remove_epi() return void, drop the dispose local in
eventpoll_release_file(), and the useless conditionals at both
callers. No functional change.
Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-9-2470f9eec0f5@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Christian Brauner
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d30deeb8b0
|
eventpoll: move f_lock acquisition into ep_remove_file()
Let the helper own its critical section end-to-end: take &file->f_lock at the top, read file->f_ep inside the lock, release on exit. Callers (ep_remove() and eventpoll_release_file()) no longer need to wrap the call, and the function-comment lock-handoff contract is gone. Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-7-2470f9eec0f5@kernel.org Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> |
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Christian Brauner
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a6dc643c69
|
eventpoll: fix ep_remove struct eventpoll / struct file UAF
ep_remove() (via ep_remove_file()) cleared file->f_ep under
file->f_lock but then kept using @file inside the critical section
(is_file_epoll(), hlist_del_rcu() through the head, spin_unlock).
A concurrent __fput() taking the eventpoll_release() fastpath in
that window observed the transient NULL, skipped
eventpoll_release_file() and ran to f_op->release / file_free().
For the epoll-watches-epoll case, f_op->release is
ep_eventpoll_release() -> ep_clear_and_put() -> ep_free(), which
kfree()s the watched struct eventpoll. Its embedded ->refs
hlist_head is exactly where epi->fllink.pprev points, so the
subsequent hlist_del_rcu()'s "*pprev = next" scribbles into freed
kmalloc-192 memory.
In addition, struct file is SLAB_TYPESAFE_BY_RCU, so the slot
backing @file could be recycled by alloc_empty_file() --
reinitializing f_lock and f_ep -- while ep_remove() is still
nominally inside that lock. The upshot is an attacker-controllable
kmem_cache_free() against the wrong slab cache.
Pin @file via epi_fget() at the top of ep_remove() and gate the
critical section on the pin succeeding. With the pin held @file
cannot reach refcount zero, which holds __fput() off and
transitively keeps the watched struct eventpoll alive across the
hlist_del_rcu() and the f_lock use, closing both UAFs.
If the pin fails @file has already reached refcount zero and its
__fput() is in flight. Because we bailed before clearing f_ep,
that path takes the eventpoll_release() slow path into
eventpoll_release_file() and blocks on ep->mtx until the waiter
side's ep_clear_and_put() drops it. The bailed epi's share of
ep->refcount stays intact, so the trailing ep_refcount_dec_and_test()
in ep_clear_and_put() cannot free the eventpoll out from under
eventpoll_release_file(); the orphaned epi is then cleaned up
there.
A successful pin also proves we are not racing
eventpoll_release_file() on this epi, so drop the now-redundant
re-check of epi->dying under f_lock. The cheap lockless
READ_ONCE(epi->dying) fast-path bailout stays.
Fixes:
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Christian Brauner
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86e87059e6
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eventpoll: move epi_fget() up
We'll need it when removing files so move it up. No functional change. Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-5-2470f9eec0f5@kernel.org Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> |
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Christian Brauner
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0bade23472
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eventpoll: rename ep_remove_safe() back to ep_remove()
The current name is just confusing and doesn't clarify anything. Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-4-2470f9eec0f5@kernel.org Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> |
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Christian Brauner
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0feaf644f7
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eventpoll: drop vestigial __ prefix from ep_remove_{file,epi}()
With __ep_remove() gone, the double-underscore on __ep_remove_file() and __ep_remove_epi() no longer contrasts with a __-less parent and just reads as noise. Rename both to ep_remove_file() and ep_remove_epi(). No functional change. Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> |
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Christian Brauner
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e9e5cd40d7
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eventpoll: kill __ep_remove()
Remove the boolean conditional in __ep_remove() and restructure the code so the check for racing with eventpoll_release_file() are only done in the ep_remove_safe() path where they belong. Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-3-2470f9eec0f5@kernel.org Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> |
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Christian Brauner
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0f7bdfd413
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eventpoll: split __ep_remove()
Split __ep_remove() to delineate file removal from epoll item removal. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-2-2470f9eec0f5@kernel.org Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> |
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Christian Brauner
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3d9fd0abc9
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eventpoll: use hlist_is_singular_node() in __ep_remove()
Replace the open-coded "epi is the only entry in file->f_ep" check with hlist_is_singular_node(). Same semantics, and the helper avoids the head-cacheline access in the common false case. Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-1-2470f9eec0f5@kernel.org Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> |
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Linus Torvalds
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b7d74ea0fd |
vfs-7.1-rc1.kino
Please consider pulling these changes from the signed vfs-7.1-rc1.kino tag. Thanks! Christian -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCadjZCgAKCRCRxhvAZXjc otmnAP4sbsxZQdz2TG2hJuOwnEZOkkxZQOUMc3ERVyZaWXIeTAEA7e5M+8FpoG9n 8ipO76UoaXdGLESrqVdp9EOhLqOW7QY= =uMeJ -----END PGP SIGNATURE----- Merge tag 'vfs-7.1-rc1.kino' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull vfs i_ino updates from Christian Brauner: "For historical reasons, the inode->i_ino field is an unsigned long, which means that it's 32 bits on 32 bit architectures. This has caused a number of filesystems to implement hacks to hash a 64-bit identifier into a 32-bit field, and deprives us of a universal identifier field for an inode. This changes the inode->i_ino field from an unsigned long to a u64. This shouldn't make any material difference on 64-bit hosts, but 32-bit hosts will see struct inode grow by at least 4 bytes. This could have effects on slabcache sizes and field alignment. The bulk of the changes are to format strings and tracepoints, since the kernel itself doesn't care that much about the i_ino field. The first patch changes some vfs function arguments, so check that one out carefully. With this change, we may be able to shrink some inode structures. For instance, struct nfs_inode has a fileid field that holds the 64-bit inode number. With this set of changes, that field could be eliminated. I'd rather leave that sort of cleanups for later just to keep this simple" * tag 'vfs-7.1-rc1.kino' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: nilfs2: fix 64-bit division operations in nilfs_bmap_find_target_in_group() EVM: add comment describing why ino field is still unsigned long vfs: remove externs from fs.h on functions modified by i_ino widening treewide: fix missed i_ino format specifier conversions ext4: fix signed format specifier in ext4_load_inode trace event treewide: change inode->i_ino from unsigned long to u64 nilfs2: widen trace event i_ino fields to u64 f2fs: widen trace event i_ino fields to u64 ext4: widen trace event i_ino fields to u64 zonefs: widen trace event i_ino fields to u64 hugetlbfs: widen trace event i_ino fields to u64 ext2: widen trace event i_ino fields to u64 cachefiles: widen trace event i_ino fields to u64 vfs: widen trace event i_ino fields to u64 net: change sock.sk_ino and sock_i_ino() to u64 audit: widen ino fields to u64 vfs: widen inode hash/lookup functions to u64 |
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Nicholas Carlini
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07712db808
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eventpoll: defer struct eventpoll free to RCU grace period
In certain situations, ep_free() in eventpoll.c will kfree the epi->ep
eventpoll struct while it still being used by another concurrent thread.
Defer the kfree() to an RCU callback to prevent UAF.
Fixes:
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Jeff Layton
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0b2600f81c
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treewide: change inode->i_ino from unsigned long to u64
On 32-bit architectures, unsigned long is only 32 bits wide, which causes 64-bit inode numbers to be silently truncated. Several filesystems (NFS, XFS, BTRFS, etc.) can generate inode numbers that exceed 32 bits, and this truncation can lead to inode number collisions and other subtle bugs on 32-bit systems. Change the type of inode->i_ino from unsigned long to u64 to ensure that inode numbers are always represented as 64-bit values regardless of architecture. Update all format specifiers treewide from %lu/%lx to %llu/%llx to match the new type, along with corresponding local variable types. This is the bulk treewide conversion. Earlier patches in this series handled trace events separately to allow trace field reordering for better struct packing on 32-bit. Signed-off-by: Jeff Layton <jlayton@kernel.org> Link: https://patch.msgid.link/20260304-iino-u64-v3-12-2257ad83d372@kernel.org Acked-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Christian Brauner <brauner@kernel.org> |
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Linus Torvalds
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0e335a7745 |
vfs-7.0-rc2.fixes
Please consider pulling these changes from the signed vfs-7.0-rc2.fixes tag.
Thanks!
Christian
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Merge tag 'vfs-7.0-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs fixes from Christian Brauner:
- Fix an uninitialized variable in file_getattr().
The flags_valid field wasn't initialized before calling
vfs_fileattr_get(), triggering KMSAN uninit-value reports in fuse
- Fix writeback wakeup and logging timeouts when DETECT_HUNG_TASK is
not enabled.
sysctl_hung_task_timeout_secs is 0 in that case causing spurious
"waiting for writeback completion for more than 1 seconds" warnings
- Fix a null-ptr-deref in do_statmount() when the mount is internal
- Add missing kernel-doc description for the @private parameter in
iomap_readahead()
- Fix mount namespace creation to hold namespace_sem across the mount
copy in create_new_namespace().
The previous drop-and-reacquire pattern was fragile and failed to
clean up mount propagation links if the real rootfs was a shared or
dependent mount
- Fix /proc mount iteration where m->index wasn't updated when
m->show() overflows, causing a restart to repeatedly show the same
mount entry in a rapidly expanding mount table
- Return EFSCORRUPTED instead of ENOSPC in minix_new_inode() when the
inode number is out of range
- Fix unshare(2) when CLONE_NEWNS is set and current->fs isn't shared.
copy_mnt_ns() received the live fs_struct so if a subsequent
namespace creation failed the rollback would leave pwd and root
pointing to detached mounts. Always allocate a new fs_struct when
CLONE_NEWNS is requested
- fserror bug fixes:
- Remove the unused fsnotify_sb_error() helper now that all callers
have been converted to fserror_report_metadata
- Fix a lockdep splat in fserror_report() where igrab() takes
inode::i_lock which can be held in IRQ context.
Replace igrab() with a direct i_count bump since filesystems
should not report inodes that are about to be freed or not yet
exposed
- Handle error pointer in procfs for try_lookup_noperm()
- Fix an integer overflow in ep_loop_check_proc() where recursive calls
returning INT_MAX would overflow when +1 is added, breaking the
recursion depth check
- Fix a misleading break in pidfs
* tag 'vfs-7.0-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
pidfs: avoid misleading break
eventpoll: Fix integer overflow in ep_loop_check_proc()
proc: Fix pointer error dereference
fserror: fix lockdep complaint when igrabbing inode
fsnotify: drop unused helper
unshare: fix unshare_fs() handling
minix: Correct errno in minix_new_inode
namespace: fix proc mount iteration
mount: hold namespace_sem across copy in create_new_namespace()
iomap: Describe @private in iomap_readahead()
statmount: Fix the null-ptr-deref in do_statmount()
writeback: Fix wakeup and logging timeouts for !DETECT_HUNG_TASK
fs: init flags_valid before calling vfs_fileattr_get
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Jann Horn
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fdcfce9307
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eventpoll: Fix integer overflow in ep_loop_check_proc()
If a recursive call to ep_loop_check_proc() hits the `result = INT_MAX`,
an integer overflow will occur in the calling ep_loop_check_proc() at
`result = max(result, ep_loop_check_proc(ep_tovisit, depth + 1) + 1)`,
breaking the recursion depth check.
Fix it by using a different placeholder value that can't lead to an
overflow.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes:
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Linus Torvalds
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bf4afc53b7 |
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kees Cook
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69050f8d6d |
treewide: Replace kmalloc with kmalloc_obj for non-scalar types
This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook <kees@kernel.org> |
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Christian Brauner
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13dce771bb
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eventpoll: convert do_epoll_create() to FD_PREPARE()
Link: https://patch.msgid.link/20251123-work-fd-prepare-v4-12-b6efa1706cfd@kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org> |
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Nam Cao
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0c43094f8c
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eventpoll: Replace rwlock with spinlock
The ready event list of an epoll object is protected by read-write semaphore: - The consumer (waiter) acquires the write lock and takes items. - the producer (waker) takes the read lock and adds items. The point of this design is enabling epoll to scale well with large number of producers, as multiple producers can hold the read lock at the same time. Unfortunately, this implementation may cause scheduling priority inversion problem. Suppose the consumer has higher scheduling priority than the producer. The consumer needs to acquire the write lock, but may be blocked by the producer holding the read lock. Since read-write semaphore does not support priority-boosting for the readers (even with CONFIG_PREEMPT_RT=y), we have a case of priority inversion: a higher priority consumer is blocked by a lower priority producer. This problem was reported in [1]. Furthermore, this could also cause stall problem, as described in [2]. Fix this problem by replacing rwlock with spinlock. This reduces the event bandwidth, as the producers now have to contend with each other for the spinlock. According to the benchmark from https://github.com/rouming/test-tools/blob/master/stress-epoll.c: On 12 x86 CPUs: Before After Diff threads events/ms events/ms 8 7162 4956 -31% 16 8733 5383 -38% 32 7968 5572 -30% 64 10652 5739 -46% 128 11236 5931 -47% On 4 riscv CPUs: Before After Diff threads events/ms events/ms 8 2958 2833 -4% 16 3323 3097 -7% 32 3451 3240 -6% 64 3554 3178 -11% 128 3601 3235 -10% Although the numbers look bad, it should be noted that this benchmark creates multiple threads who do nothing except constantly generating new epoll events, thus contention on the spinlock is high. For real workload, the event rate is likely much lower, and the performance drop is not as bad. Using another benchmark (perf bench epoll wait) where spinlock contention is lower, improvement is even observed on x86: On 12 x86 CPUs: Before: Averaged 110279 operations/sec (+- 1.09%), total secs = 8 After: Averaged 114577 operations/sec (+- 2.25%), total secs = 8 On 4 riscv CPUs: Before: Averaged 175767 operations/sec (+- 0.62%), total secs = 8 After: Averaged 167396 operations/sec (+- 0.23%), total secs = 8 In conclusion, no one is likely to be upset over this change. After all, spinlock was used originally for years, and the commit which converted to rwlock didn't mention a real workload, just that the benchmark numbers are nice. This patch is not exactly the revert of commit |
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Linus Torvalds
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7879d7aff0 |
vfs-6.17-rc1.misc
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Merge tag 'vfs-6.17-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc VFS updates from Christian Brauner:
"This contains the usual selections of misc updates for this cycle.
Features:
- Add ext4 IOCB_DONTCACHE support
This refactors the address_space_operations write_begin() and
write_end() callbacks to take const struct kiocb * as their first
argument, allowing IOCB flags such as IOCB_DONTCACHE to propagate
to the filesystem's buffered I/O path.
Ext4 is updated to implement handling of the IOCB_DONTCACHE flag
and advertises support via the FOP_DONTCACHE file operation flag.
Additionally, the i915 driver's shmem write paths are updated to
bypass the legacy write_begin/write_end interface in favor of
directly calling write_iter() with a constructed synchronous kiocb.
Another i915 change replaces a manual write loop with
kernel_write() during GEM shmem object creation.
Cleanups:
- don't duplicate vfs_open() in kernel_file_open()
- proc_fd_getattr(): don't bother with S_ISDIR() check
- fs/ecryptfs: replace snprintf with sysfs_emit in show function
- vfs: Remove unnecessary list_for_each_entry_safe() from
evict_inodes()
- filelock: add new locks_wake_up_waiter() helper
- fs: Remove three arguments from block_write_end()
- VFS: change old_dir and new_dir in struct renamedata to dentrys
- netfs: Remove unused declaration netfs_queue_write_request()
Fixes:
- eventpoll: Fix semi-unbounded recursion
- eventpoll: fix sphinx documentation build warning
- fs/read_write: Fix spelling typo
- fs: annotate data race between poll_schedule_timeout() and
pollwake()
- fs/pipe: set FMODE_NOWAIT in create_pipe_files()
- docs/vfs: update references to i_mutex to i_rwsem
- fs/buffer: remove comment about hard sectorsize
- fs/buffer: remove the min and max limit checks in __getblk_slow()
- fs/libfs: don't assume blocksize <= PAGE_SIZE in
generic_check_addressable
- fs_context: fix parameter name in infofc() macro
- fs: Prevent file descriptor table allocations exceeding INT_MAX"
* tag 'vfs-6.17-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (24 commits)
netfs: Remove unused declaration netfs_queue_write_request()
eventpoll: fix sphinx documentation build warning
ext4: support uncached buffered I/O
mm/pagemap: add write_begin_get_folio() helper function
fs: change write_begin/write_end interface to take struct kiocb *
drm/i915: Refactor shmem_pwrite() to use kiocb and write_iter
drm/i915: Use kernel_write() in shmem object create
eventpoll: Fix semi-unbounded recursion
vfs: Remove unnecessary list_for_each_entry_safe() from evict_inodes()
fs/libfs: don't assume blocksize <= PAGE_SIZE in generic_check_addressable
fs/buffer: remove the min and max limit checks in __getblk_slow()
fs: Prevent file descriptor table allocations exceeding INT_MAX
fs: Remove three arguments from block_write_end()
fs/ecryptfs: replace snprintf with sysfs_emit in show function
fs: annotate suspected data race between poll_schedule_timeout() and pollwake()
docs/vfs: update references to i_mutex to i_rwsem
fs/buffer: remove comment about hard sectorsize
fs_context: fix parameter name in infofc() macro
VFS: change old_dir and new_dir in struct renamedata to dentrys
proc_fd_getattr(): don't bother with S_ISDIR() check
...
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Jann Horn
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ecb6cc0fd8
|
eventpoll: fix sphinx documentation build warning
Sphinx complains that ep_get_upwards_depth_proc() has a kerneldoc-style
comment without documenting its parameters.
This is an internal function that was not meant to show up in kernel
documentation, so fix the warning by changing the comment to a
non-kerneldoc one.
Fixes:
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Jann Horn
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f2e467a482
|
eventpoll: Fix semi-unbounded recursion
Ensure that epoll instances can never form a graph deeper than EP_MAX_NESTS+1 links. Currently, ep_loop_check_proc() ensures that the graph is loop-free and does some recursion depth checks, but those recursion depth checks don't limit the depth of the resulting tree for two reasons: - They don't look upwards in the tree. - If there are multiple downwards paths of different lengths, only one of the paths is actually considered for the depth check since commit |
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Linus Torvalds
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5f02b80c21 |
Revert "eventpoll: Fix priority inversion problem"
This reverts commit
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Linus Torvalds
|
8c2e52ebbe |
eventpoll: don't decrement ep refcount while still holding the ep mutex
Jann Horn points out that epoll is decrementing the ep refcount and then
doing a
mutex_unlock(&ep->mtx);
afterwards. That's very wrong, because it can lead to a use-after-free.
That pattern is actually fine for the very last reference, because the
code in question will delay the actual call to "ep_free(ep)" until after
it has unlocked the mutex.
But it's wrong for the much subtler "next to last" case when somebody
*else* may also be dropping their reference and free the ep while we're
still using the mutex.
Note that this is true even if that other user is also using the same ep
mutex: mutexes, unlike spinlocks, can not be used for object ownership,
even if they guarantee mutual exclusion.
A mutex "unlock" operation is not atomic, and as one user is still
accessing the mutex as part of unlocking it, another user can come in
and get the now released mutex and free the data structure while the
first user is still cleaning up.
See our mutex documentation in Documentation/locking/mutex-design.rst,
in particular the section [1] about semantics:
"mutex_unlock() may access the mutex structure even after it has
internally released the lock already - so it's not safe for
another context to acquire the mutex and assume that the
mutex_unlock() context is not using the structure anymore"
So if we drop our ep ref before the mutex unlock, but we weren't the
last one, we may then unlock the mutex, another user comes in, drops
_their_ reference and releases the 'ep' as it now has no users - all
while the mutex_unlock() is still accessing it.
Fix this by simply moving the ep refcount dropping to outside the mutex:
the refcount itself is atomic, and doesn't need mutex protection (that's
the whole _point_ of refcounts: unlike mutexes, they are inherently
about object lifetimes).
Reported-by: Jann Horn <jannh@google.com>
Link: https://docs.kernel.org/locking/mutex-design.html#semantics [1]
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Nam Cao
|
8c44dac8ad
|
eventpoll: Fix priority inversion problem
The ready event list of an epoll object is protected by read-write semaphore: - The consumer (waiter) acquires the write lock and takes items. - the producer (waker) takes the read lock and adds items. The point of this design is enabling epoll to scale well with large number of producers, as multiple producers can hold the read lock at the same time. Unfortunately, this implementation may cause scheduling priority inversion problem. Suppose the consumer has higher scheduling priority than the producer. The consumer needs to acquire the write lock, but may be blocked by the producer holding the read lock. Since read-write semaphore does not support priority-boosting for the readers (even with CONFIG_PREEMPT_RT=y), we have a case of priority inversion: a higher priority consumer is blocked by a lower priority producer. This problem was reported in [1]. Furthermore, this could also cause stall problem, as described in [2]. To fix this problem, make the event list half-lockless: - The consumer acquires a mutex (ep->mtx) and takes items. - The producer locklessly adds items to the list. Performance is not the main goal of this patch, but as the producer now can add items without waiting for consumer to release the lock, performance improvement is observed using the stress test from https://github.com/rouming/test-tools/blob/master/stress-epoll.c. This is the same test that justified using read-write semaphore in the past. Testing using 12 x86_64 CPUs: Before After Diff threads events/ms events/ms 8 6932 19753 +185% 16 7820 27923 +257% 32 7648 35164 +360% 64 9677 37780 +290% 128 11166 38174 +242% Testing using 1 riscv64 CPU (averaged over 10 runs, as the numbers are noisy): Before After Diff threads events/ms events/ms 1 73 129 +77% 2 151 216 +43% 4 216 364 +69% 8 234 382 +63% 16 251 392 +56% Reported-by: Frederic Weisbecker <frederic@kernel.org> Closes: https://lore.kernel.org/linux-rt-users/20210825132754.GA895675@lothringen/ [1] Reported-by: Valentin Schneider <vschneid@redhat.com> Closes: https://lore.kernel.org/linux-rt-users/xhsmhttqvnall.mognet@vschneid.remote.csb/ [2] Signed-off-by: Nam Cao <namcao@linutronix.de> Link: https://lore.kernel.org/20250527090836.1290532-1-namcao@linutronix.de Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Acked-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org> |
||
|
Max Kellermann
|
d9ec733010
|
fs/eventpoll: fix endless busy loop after timeout has expired
After commit |
||
|
Joe Damato
|
0a65bc27bd
|
eventpoll: Set epoll timeout if it's in the future
Avoid an edge case where epoll_wait arms a timer and calls schedule()
even if the timer will expire immediately.
For example: if the user has specified an epoll busy poll usecs which is
equal or larger than the epoll_wait/epoll_pwait2 timeout, it is
unnecessary to call schedule_hrtimeout_range; the busy poll usecs have
consumed the entire timeout duration so it is unnecessary to induce
scheduling latency by calling schedule() (via schedule_hrtimeout_range).
This can be measured using a simple bpftrace script:
tracepoint:sched:sched_switch
/ args->prev_pid == $1 /
{
print(kstack());
print(ustack());
}
Before this patch is applied:
Testing an epoll_wait app with busy poll usecs set to 1000, and
epoll_wait timeout set to 1ms using the script above shows:
__traceiter_sched_switch+69
__schedule+1495
schedule+32
schedule_hrtimeout_range+159
do_epoll_wait+1424
__x64_sys_epoll_wait+97
do_syscall_64+95
entry_SYSCALL_64_after_hwframe+118
epoll_wait+82
Which is unexpected; the busy poll usecs should have consumed the
entire timeout and there should be no reason to arm a timer.
After this patch is applied: the same test scenario does not generate a
call to schedule() in the above edge case. If the busy poll usecs are
reduced (for example usecs: 100, epoll_wait timeout 1ms) the timer is
armed as expected.
Fixes:
|
||
|
Linus Torvalds
|
1a9239bb42 |
Networking changes for 6.15.
Core & protocols
----------------
- Continue Netlink conversions to per-namespace RTNL lock
(IPv4 routing, routing rules, routing next hops, ARP ioctls).
- Continue extending the use of netdev instance locks. As a driver
opt-in protect queue operations and (in due course) ethtool
operations with the instance lock and not RTNL lock.
- Support collecting TCP timestamps (data submitted, sent, acked)
in BPF, allowing for transparent (to the application) and lower
overhead tracking of TCP RPC performance.
- Tweak existing networking Rx zero-copy infra to support zero-copy
Rx via io_uring.
- Optimize MPTCP performance in single subflow mode by 29%.
- Enable GRO on packets which went thru XDP CPU redirect (were queued
for processing on a different CPU). Improving TCP stream performance
up to 2x.
- Improve performance of contended connect() by 200% by searching
for an available 4-tuple under RCU rather than a spin lock.
Bring an additional 229% improvement by tweaking hash distribution.
- Avoid unconditionally touching sk_tsflags on RX, improving
performance under UDP flood by as much as 10%.
- Avoid skb_clone() dance in ping_rcv() to improve performance under
ping flood.
- Avoid FIB lookup in netfilter if socket is available, 20% perf win.
- Rework network device creation (in-kernel) API to more clearly
identify network namespaces and their roles.
There are up to 4 namespace roles but we used to have just 2 netns
pointer arguments, interpreted differently based on context.
- Use sysfs_break_active_protection() instead of trylock to avoid
deadlocks between unregistering objects and sysfs access.
- Add a new sysctl and sockopt for capping max retransmit timeout
in TCP.
- Support masking port and DSCP in routing rule matches.
- Support dumping IPv4 multicast addresses with RTM_GETMULTICAST.
- Support specifying at what time packet should be sent on AF_XDP
sockets.
- Expose TCP ULP diagnostic info (for TLS and MPTCP) to non-admin users.
- Add Netlink YAML spec for WiFi (nl80211) and conntrack.
- Introduce EXPORT_IPV6_MOD() and EXPORT_IPV6_MOD_GPL() for symbols
which only need to be exported when IPv6 support is built as a module.
- Age FDB entries based on Rx not Tx traffic in VxLAN, similar
to normal bridging.
- Allow users to specify source port range for GENEVE tunnels.
- netconsole: allow attaching kernel release, CPU ID and task name
to messages as metadata
Driver API
----------
- Continue rework / fixing of Energy Efficient Ethernet (EEE) across
the SW layers. Delegate the responsibilities to phylink where possible.
Improve its handling in phylib.
- Support symmetric OR-XOR RSS hashing algorithm.
- Support tracking and preserving IRQ affinity by NAPI itself.
- Support loopback mode speed selection for interface selftests.
Device drivers
--------------
- Remove the IBM LCS driver for s390.
- Remove the sb1000 cable modem driver.
- Add support for SFP module access over SMBus.
- Add MCTP transport driver for MCTP-over-USB.
- Enable XDP metadata support in multiple drivers.
- Ethernet high-speed NICs:
- Broadcom (bnxt):
- add PCIe TLP Processing Hints (TPH) support for new AMD platforms
- support dumping RoCE queue state for debug
- opt into instance locking
- Intel (100G, ice, idpf):
- ice: rework MSI-X IRQ management and distribution
- ice: support for E830 devices
- iavf: add support for Rx timestamping
- iavf: opt into instance locking
- nVidia/Mellanox:
- mlx4: use page pool memory allocator for Rx
- mlx5: support for one PTP device per hardware clock
- mlx5: support for 200Gbps per-lane link modes
- mlx5: move IPSec policy check after decryption
- AMD/Solarflare:
- support FW flashing via devlink
- Cisco (enic):
- use page pool memory allocator for Rx
- enable 32, 64 byte CQEs
- get max rx/tx ring size from the device
- Meta (fbnic):
- support flow steering and RSS configuration
- report queue stats
- support TCP segmentation
- support IRQ coalescing
- support ring size configuration
- Marvell/Cavium:
- support AF_XDP
- Wangxun:
- support for PTP clock and timestamping
- Huawei (hibmcge):
- checksum offload
- add more statistics
- Ethernet virtual:
- VirtIO net:
- aggressively suppress Tx completions, improve perf by 96% with
1 CPU and 55% with 2 CPUs
- expose NAPI to IRQ mapping and persist NAPI settings
- Google (gve):
- support XDP in DQO RDA Queue Format
- opt into instance locking
- Microsoft vNIC:
- support BIG TCP
- Ethernet NICs consumer, and embedded:
- Synopsys (stmmac):
- cleanup Tx and Tx clock setting and other link-focused cleanups
- enable SGMII and 2500BASEX mode switching for Intel platforms
- support Sophgo SG2044
- Broadcom switches (b53):
- support for BCM53101
- TI:
- iep: add perout configuration support
- icssg: support XDP
- Cadence (macb):
- implement BQL
- Xilinx (axinet):
- support dynamic IRQ moderation and changing coalescing at runtime
- implement BQL
- report standard stats
- MediaTek:
- support phylink managed EEE
- Intel:
- igc: don't restart the interface on every XDP program change
- RealTek (r8169):
- support reading registers of internal PHYs directly
- increase max jumbo packet size on RTL8125/RTL8126
- Airoha:
- support for RISC-V NPU packet processing unit
- enable scatter-gather and support MTU up to 9kB
- Tehuti (tn40xx):
- support cards with TN4010 MAC and an Aquantia AQR105 PHY
- Ethernet PHYs:
- support for TJA1102S, TJA1121
- dp83tg720: add randomized polling intervals for link detection
- dp83822: support changing the transmit amplitude voltage
- support for LEDs on 88q2xxx
- CAN:
- canxl: support Remote Request Substitution bit access
- flexcan: add S32G2/S32G3 SoC
- WiFi:
- remove cooked monitor support
- strict mode for better AP testing
- basic EPCS support
- OMI RX bandwidth reduction support
- batman-adv: add support for jumbo frames
- WiFi drivers:
- RealTek (rtw88):
- support RTL8814AE and RTL8814AU
- RealTek (rtw89):
- switch using wiphy_lock and wiphy_work
- add BB context to manipulate two PHY as preparation of MLO
- improve BT-coexistence mechanism to play A2DP smoothly
- Intel (iwlwifi):
- add new iwlmld sub-driver for latest HW/FW combinations
- MediaTek (mt76):
- preparation for mt7996 Multi-Link Operation (MLO) support
- Qualcomm/Atheros (ath12k):
- continued work on MLO
- Silabs (wfx):
- Wake-on-WLAN support
- Bluetooth:
- add support for skb TX SND/COMPLETION timestamping
- hci_core: enable buffer flow control for SCO/eSCO
- coredump: log devcd dumps into the monitor
- Bluetooth drivers:
- intel: add support to configure TX power
- nxp: handle bootloader error during cmd5 and cmd7
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-next-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
"Core & protocols:
- Continue Netlink conversions to per-namespace RTNL lock
(IPv4 routing, routing rules, routing next hops, ARP ioctls)
- Continue extending the use of netdev instance locks. As a driver
opt-in protect queue operations and (in due course) ethtool
operations with the instance lock and not RTNL lock.
- Support collecting TCP timestamps (data submitted, sent, acked) in
BPF, allowing for transparent (to the application) and lower
overhead tracking of TCP RPC performance.
- Tweak existing networking Rx zero-copy infra to support zero-copy
Rx via io_uring.
- Optimize MPTCP performance in single subflow mode by 29%.
- Enable GRO on packets which went thru XDP CPU redirect (were queued
for processing on a different CPU). Improving TCP stream
performance up to 2x.
- Improve performance of contended connect() by 200% by searching for
an available 4-tuple under RCU rather than a spin lock. Bring an
additional 229% improvement by tweaking hash distribution.
- Avoid unconditionally touching sk_tsflags on RX, improving
performance under UDP flood by as much as 10%.
- Avoid skb_clone() dance in ping_rcv() to improve performance under
ping flood.
- Avoid FIB lookup in netfilter if socket is available, 20% perf win.
- Rework network device creation (in-kernel) API to more clearly
identify network namespaces and their roles. There are up to 4
namespace roles but we used to have just 2 netns pointer arguments,
interpreted differently based on context.
- Use sysfs_break_active_protection() instead of trylock to avoid
deadlocks between unregistering objects and sysfs access.
- Add a new sysctl and sockopt for capping max retransmit timeout in
TCP.
- Support masking port and DSCP in routing rule matches.
- Support dumping IPv4 multicast addresses with RTM_GETMULTICAST.
- Support specifying at what time packet should be sent on AF_XDP
sockets.
- Expose TCP ULP diagnostic info (for TLS and MPTCP) to non-admin
users.
- Add Netlink YAML spec for WiFi (nl80211) and conntrack.
- Introduce EXPORT_IPV6_MOD() and EXPORT_IPV6_MOD_GPL() for symbols
which only need to be exported when IPv6 support is built as a
module.
- Age FDB entries based on Rx not Tx traffic in VxLAN, similar to
normal bridging.
- Allow users to specify source port range for GENEVE tunnels.
- netconsole: allow attaching kernel release, CPU ID and task name to
messages as metadata
Driver API:
- Continue rework / fixing of Energy Efficient Ethernet (EEE) across
the SW layers. Delegate the responsibilities to phylink where
possible. Improve its handling in phylib.
- Support symmetric OR-XOR RSS hashing algorithm.
- Support tracking and preserving IRQ affinity by NAPI itself.
- Support loopback mode speed selection for interface selftests.
Device drivers:
- Remove the IBM LCS driver for s390
- Remove the sb1000 cable modem driver
- Add support for SFP module access over SMBus
- Add MCTP transport driver for MCTP-over-USB
- Enable XDP metadata support in multiple drivers
- Ethernet high-speed NICs:
- Broadcom (bnxt):
- add PCIe TLP Processing Hints (TPH) support for new AMD
platforms
- support dumping RoCE queue state for debug
- opt into instance locking
- Intel (100G, ice, idpf):
- ice: rework MSI-X IRQ management and distribution
- ice: support for E830 devices
- iavf: add support for Rx timestamping
- iavf: opt into instance locking
- nVidia/Mellanox:
- mlx4: use page pool memory allocator for Rx
- mlx5: support for one PTP device per hardware clock
- mlx5: support for 200Gbps per-lane link modes
- mlx5: move IPSec policy check after decryption
- AMD/Solarflare:
- support FW flashing via devlink
- Cisco (enic):
- use page pool memory allocator for Rx
- enable 32, 64 byte CQEs
- get max rx/tx ring size from the device
- Meta (fbnic):
- support flow steering and RSS configuration
- report queue stats
- support TCP segmentation
- support IRQ coalescing
- support ring size configuration
- Marvell/Cavium:
- support AF_XDP
- Wangxun:
- support for PTP clock and timestamping
- Huawei (hibmcge):
- checksum offload
- add more statistics
- Ethernet virtual:
- VirtIO net:
- aggressively suppress Tx completions, improve perf by 96%
with 1 CPU and 55% with 2 CPUs
- expose NAPI to IRQ mapping and persist NAPI settings
- Google (gve):
- support XDP in DQO RDA Queue Format
- opt into instance locking
- Microsoft vNIC:
- support BIG TCP
- Ethernet NICs consumer, and embedded:
- Synopsys (stmmac):
- cleanup Tx and Tx clock setting and other link-focused
cleanups
- enable SGMII and 2500BASEX mode switching for Intel platforms
- support Sophgo SG2044
- Broadcom switches (b53):
- support for BCM53101
- TI:
- iep: add perout configuration support
- icssg: support XDP
- Cadence (macb):
- implement BQL
- Xilinx (axinet):
- support dynamic IRQ moderation and changing coalescing at
runtime
- implement BQL
- report standard stats
- MediaTek:
- support phylink managed EEE
- Intel:
- igc: don't restart the interface on every XDP program change
- RealTek (r8169):
- support reading registers of internal PHYs directly
- increase max jumbo packet size on RTL8125/RTL8126
- Airoha:
- support for RISC-V NPU packet processing unit
- enable scatter-gather and support MTU up to 9kB
- Tehuti (tn40xx):
- support cards with TN4010 MAC and an Aquantia AQR105 PHY
- Ethernet PHYs:
- support for TJA1102S, TJA1121
- dp83tg720: add randomized polling intervals for link detection
- dp83822: support changing the transmit amplitude voltage
- support for LEDs on 88q2xxx
- CAN:
- canxl: support Remote Request Substitution bit access
- flexcan: add S32G2/S32G3 SoC
- WiFi:
- remove cooked monitor support
- strict mode for better AP testing
- basic EPCS support
- OMI RX bandwidth reduction support
- batman-adv: add support for jumbo frames
- WiFi drivers:
- RealTek (rtw88):
- support RTL8814AE and RTL8814AU
- RealTek (rtw89):
- switch using wiphy_lock and wiphy_work
- add BB context to manipulate two PHY as preparation of MLO
- improve BT-coexistence mechanism to play A2DP smoothly
- Intel (iwlwifi):
- add new iwlmld sub-driver for latest HW/FW combinations
- MediaTek (mt76):
- preparation for mt7996 Multi-Link Operation (MLO) support
- Qualcomm/Atheros (ath12k):
- continued work on MLO
- Silabs (wfx):
- Wake-on-WLAN support
- Bluetooth:
- add support for skb TX SND/COMPLETION timestamping
- hci_core: enable buffer flow control for SCO/eSCO
- coredump: log devcd dumps into the monitor
- Bluetooth drivers:
- intel: add support to configure TX power
- nxp: handle bootloader error during cmd5 and cmd7"
* tag 'net-next-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1681 commits)
unix: fix up for "apparmor: add fine grained af_unix mediation"
mctp: Fix incorrect tx flow invalidation condition in mctp-i2c
net: usb: asix: ax88772: Increase phy_name size
net: phy: Introduce PHY_ID_SIZE — minimum size for PHY ID string
net: libwx: fix Tx L4 checksum
net: libwx: fix Tx descriptor content for some tunnel packets
atm: Fix NULL pointer dereference
net: tn40xx: add pci-id of the aqr105-based Tehuti TN4010 cards
net: tn40xx: prepare tn40xx driver to find phy of the TN9510 card
net: tn40xx: create swnode for mdio and aqr105 phy and add to mdiobus
net: phy: aquantia: add essential functions to aqr105 driver
net: phy: aquantia: search for firmware-name in fwnode
net: phy: aquantia: add probe function to aqr105 for firmware loading
net: phy: Add swnode support to mdiobus_scan
gve: add XDP DROP and PASS support for DQ
gve: update XDP allocation path support RX buffer posting
gve: merge packet buffer size fields
gve: update GQ RX to use buf_size
gve: introduce config-based allocation for XDP
gve: remove xdp_xsk_done and xdp_xsk_wakeup statistics
...
|
||
|
Linus Torvalds
|
a79a09a025 |
vfs-6.15-rc1.eventpoll
-----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCZ90rgwAKCRCRxhvAZXjc on04AP992qy1uWn3K0IHmNU3GJo3LNPE5NBWPYOq56IuCLbQqwEA7QgxASGQgH0l wBz7qtQxfq/0GoklbMATqkZBkzk6ugo= =Uau0 -----END PGP SIGNATURE----- Merge tag 'vfs-6.15-rc1.eventpoll' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull vfs eventpoll updates from Christian Brauner: "This contains a few preparatory changes to eventpoll to allow io_uring to support epoll" * tag 'vfs-6.15-rc1.eventpoll' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: eventpoll: add epoll_sendevents() helper eventpoll: abstract out ep_try_send_events() helper eventpoll: abstract out parameter sanity checking |
||
|
Lin Feng
|
d3a194d95f
|
epoll: simplify ep_busy_loop by removing always 0 argument
Commit 00b27634bc471("epoll: replace gotos with a proper loop") refactored
ep_poll and always feeds ep_busy_loop with a time_out value of 0, nonblock
mode for ep_busy_loop has sunk since, IOW nonblock mode checking has been
taken over by ep_poll itself, codes snipped:
static int ep_poll(struct eventpoll *ep...
{
...
if (timed_out)
return 0;
eavail = ep_busy_loop(ep, timed_out);
...
}
Given this fact codes can be simplified a bit for ep_busy_loop.
Signed-off-by: Lin Feng <linf@wangsu.com>
Link: https://lore.kernel.org/r/20250227033412.5873-1-linf@wangsu.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
||
|
Jens Axboe
|
ae3a4f1fdc
|
eventpoll: add epoll_sendevents() helper
Basic helper that copies ready events to the specified userspace address. The event checking is quick and racy, it's up to the caller to ensure it retries appropriately in case 0 events are copied. Signed-off-by: Jens Axboe <axboe@kernel.dk> Link: https://lore.kernel.org/r/20250219172552.1565603-4-axboe@kernel.dk Signed-off-by: Christian Brauner <brauner@kernel.org> |
||
|
Jens Axboe
|
38d2035601
|
eventpoll: abstract out ep_try_send_events() helper
In preparation for reusing this helper in another epoll setup helper, abstract it out. Signed-off-by: Jens Axboe <axboe@kernel.dk> Link: https://lore.kernel.org/r/20250219172552.1565603-3-axboe@kernel.dk Signed-off-by: Christian Brauner <brauner@kernel.org> |
||
|
Jens Axboe
|
6b47d35d4d
|
eventpoll: abstract out parameter sanity checking
Add a helper that checks the validity of the file descriptor and other parameters passed in to epoll_wait(). Signed-off-by: Jens Axboe <axboe@kernel.dk> Link: https://lore.kernel.org/r/20250219172552.1565603-2-axboe@kernel.dk Signed-off-by: Christian Brauner <brauner@kernel.org> |
||
|
Stefano Jordhani
|
b9d752105e |
net: use napi_id_valid helper
In commit
|
||
|
Joel Granados
|
1751f872cc |
treewide: const qualify ctl_tables where applicable
Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.
Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit
|
||
|
Linus Torvalds
|
fcc79e1714 |
Networking changes for 6.13.
The most significant set of changes is the per netns RTNL. The new
behavior is disabled by default, regression risk should be contained.
Notably the new config knob PTP_1588_CLOCK_VMCLOCK will inherit its
default value from PTP_1588_CLOCK_KVM, as the first is intended to be
a more reliable replacement for the latter.
Core
----
- Started a very large, in-progress, effort to make the RTNL lock
scope per network-namespace, thus reducing the lock contention
significantly in the containerized use-case, comprising:
- RCU-ified some relevant slices of the FIB control path
- introduce basic per netns locking helpers
- namespacified the IPv4 address hash table
- remove rtnl_register{,_module}() in favour of rtnl_register_many()
- refactor rtnl_{new,del,set}link() moving as much validation as
possible out of RTNL lock
- convert all phonet doit() and dumpit() handlers to RCU
- convert IPv4 addresses manipulation to per-netns RTNL
- convert virtual interface creation to per-netns RTNL
the per-netns lock infra is guarded by the CONFIG_DEBUG_NET_SMALL_RTNL
knob, disabled by default ad interim.
- Introduce NAPI suspension, to efficiently switching between busy
polling (NAPI processing suspended) and normal processing.
- Migrate the IPv4 routing input, output and control path from direct
ToS usage to DSCP macros. This is a work in progress to make ECN
handling consistent and reliable.
- Add drop reasons support to the IPv4 rotue input path, allowing
better introspection in case of packets drop.
- Make FIB seqnum lockless, dropping RTNL protection for read
access.
- Make inet{,v6} addresses hashing less predicable.
- Allow providing timestamp OPT_ID via cmsg, to correlate TX packets
and timestamps
Things we sprinkled into general kernel code
--------------------------------------------
- Add small file operations for debugfs, to reduce the struct ops size.
- Refactoring and optimization for the implementation of page_frag API,
This is a preparatory work to consolidate the page_frag
implementation.
Netfilter
---------
- Optimize set element transactions to reduce memory consumption
- Extended netlink error reporting for attribute parser failure.
- Make legacy xtables configs user selectable, giving users
the option to configure iptables without enabling any other config.
- Address a lot of false-positive RCU issues, pointed by recent
CI improvements.
BPF
---
- Put xsk sockets on a struct diet and add various cleanups. Overall,
this helps to bump performance by 12% for some workloads.
- Extend BPF selftests to increase coverage of XDP features in
combination with BPF cpumap.
- Optimize and homogenize bpf_csum_diff helper for all archs and also
add a batch of new BPF selftests for it.
- Extend netkit with an option to delegate skb->{mark,priority}
scrubbing to its BPF program.
- Make the bpf_get_netns_cookie() helper available also to tc(x) BPF
programs.
Protocols
---------
- Introduces 4-tuple hash for connected udp sockets, speeding-up
significantly connected sockets lookup.
- Add a fastpath for some TCP timers that usually expires after close,
the socket lock contention.
- Add inbound and outbound xfrm state caches to speed up state lookups.
- Avoid sending MPTCP advertisements on stale subflows, reducing
risks on loosing them.
- Make neighbours table flushing more scalable, maintaining per device
neigh lists.
Driver API
----------
- Introduce a unified interface to configure transmission H/W shaping,
and expose it to user-space via generic-netlink.
- Add support for per-NAPI config via netlink. This makes napi
configuration persistent across queues removal and re-creation.
Requires driver updates, currently supported drivers are:
nVidia/Mellanox mlx4 and mlx5, Broadcom brcm and Intel ice.
- Add ethtool support for writing SFP / PHY firmware blocks.
- Track RSS context allocation from ethtool core.
- Implement support for mirroring to DSA CPU port, via TC mirror
offload.
- Consolidate FDB updates notification, to avoid duplicates on
device-specific entries.
- Expose DPLL clock quality level to the user-space.
- Support master-slave PHY config via device tree.
Tests and tooling
-----------------
- forwarding: introduce deferred commands, to simplify
the cleanup phase
Drivers
-------
- Updated several drivers - Amazon vNic, Google vNic, Microsoft vNic,
Intel e1000e and Broadcom Tigon3 - to use netdev-genl to link the
IRQs and queues to NAPI IDs, allowing busy polling and better
introspection.
- Ethernet high-speed NICs:
- nVidia/Mellanox:
- mlx5:
- a large refactor to implement support for cross E-Switch
scheduling
- refactor H/W conter management to let it scale better
- H/W GRO cleanups
- Intel (100G, ice)::
- adds support for ethtool reset
- implement support for per TX queue H/W shaping
- AMD/Solarflare:
- implement per device queue stats support
- Broadcom (bnxt):
- improve wildcard l4proto on IPv4/IPv6 ntuple rules
- Marvell Octeon:
- Adds representor support for each Resource Virtualization Unit
(RVU) device.
- Hisilicon:
- adds support for the BMC Gigabit Ethernet
- IBM (EMAC):
- driver cleanup and modernization
- Cisco (VIC):
- raise the queues number limit to 256
- Ethernet virtual:
- Google vNIC:
- implements page pool support
- macsec:
- inherit lower device's features and TSO limits when offloading
- virtio_net:
- enable premapped mode by default
- support for XDP socket(AF_XDP) zerocopy TX
- wireguard:
- set the TSO max size to be GSO_MAX_SIZE, to aggregate larger
packets.
- Ethernet NICs embedded and virtual:
- Broadcom ASP:
- enable software timestamping
- Freescale:
- add enetc4 PF driver
- MediaTek: Airoha SoC:
- implement BQL support
- RealTek r8169:
- enable TSO by default on r8168/r8125
- implement extended ethtool stats
- Renesas AVB:
- enable TX checksum offload
- Synopsys (stmmac):
- support header splitting for vlan tagged packets
- move common code for DWMAC4 and DWXGMAC into a separate FPE
module.
- Add the dwmac driver support for T-HEAD TH1520 SoC
- Synopsys (xpcs):
- driver refactor and cleanup
- TI:
- icssg_prueth: add VLAN offload support
- Xilinx emaclite:
- adds clock support
- Ethernet switches:
- Microchip:
- implement support for the lan969x Ethernet switch family
- add LAN9646 switch support to KSZ DSA driver
- Ethernet PHYs:
- Marvel: 88q2x: enable auto negotiation
- Microchip: add support for LAN865X Rev B1 and LAN867X Rev C1/C2
- PTP:
- Add support for the Amazon virtual clock device
- Add PtP driver for s390 clocks
- WiFi:
- mac80211
- EHT 1024 aggregation size for transmissions
- new operation to indicate that a new interface is to be added
- support radio separation of multi-band devices
- move wireless extension spy implementation to libiw
- Broadcom:
- brcmfmac: optional LPO clock support
- Microchip:
- add support for Atmel WILC3000
- Qualcomm (ath12k):
- firmware coredump collection support
- add debugfs support for a multitude of statistics
- Qualcomm (ath5k):
- Arcadyan ARV45XX AR2417 & Gigaset SX76[23] AR241[34]A support
- Realtek:
- rtw88: 8821au and 8812au USB adapters support
- rtw89: add thermal protection
- rtw89: fine tune BT-coexsitence to improve user experience
- rtw89: firmware secure boot for WiFi 6 chip
- Bluetooth
- add Qualcomm WCN785x support for ids Foxconn 0xe0fc/0xe0f3 and
0x13d3:0x3623
- add Realtek RTL8852BE support for id Foxconn 0xe123
- add MediaTek MT7920 support for wireless module ids
- btintel_pcie: add handshake between driver and firmware
- btintel_pcie: add recovery mechanism
- btnxpuart: add GPIO support to power save feature
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Merge tag 'net-next-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Paolo Abeni:
"The most significant set of changes is the per netns RTNL. The new
behavior is disabled by default, regression risk should be contained.
Notably the new config knob PTP_1588_CLOCK_VMCLOCK will inherit its
default value from PTP_1588_CLOCK_KVM, as the first is intended to be
a more reliable replacement for the latter.
Core:
- Started a very large, in-progress, effort to make the RTNL lock
scope per network-namespace, thus reducing the lock contention
significantly in the containerized use-case, comprising:
- RCU-ified some relevant slices of the FIB control path
- introduce basic per netns locking helpers
- namespacified the IPv4 address hash table
- remove rtnl_register{,_module}() in favour of
rtnl_register_many()
- refactor rtnl_{new,del,set}link() moving as much validation as
possible out of RTNL lock
- convert all phonet doit() and dumpit() handlers to RCU
- convert IPv4 addresses manipulation to per-netns RTNL
- convert virtual interface creation to per-netns RTNL
the per-netns lock infrastructure is guarded by the
CONFIG_DEBUG_NET_SMALL_RTNL knob, disabled by default ad interim.
- Introduce NAPI suspension, to efficiently switching between busy
polling (NAPI processing suspended) and normal processing.
- Migrate the IPv4 routing input, output and control path from direct
ToS usage to DSCP macros. This is a work in progress to make ECN
handling consistent and reliable.
- Add drop reasons support to the IPv4 rotue input path, allowing
better introspection in case of packets drop.
- Make FIB seqnum lockless, dropping RTNL protection for read access.
- Make inet{,v6} addresses hashing less predicable.
- Allow providing timestamp OPT_ID via cmsg, to correlate TX packets
and timestamps
Things we sprinkled into general kernel code:
- Add small file operations for debugfs, to reduce the struct ops
size.
- Refactoring and optimization for the implementation of page_frag
API, This is a preparatory work to consolidate the page_frag
implementation.
Netfilter:
- Optimize set element transactions to reduce memory consumption
- Extended netlink error reporting for attribute parser failure.
- Make legacy xtables configs user selectable, giving users the
option to configure iptables without enabling any other config.
- Address a lot of false-positive RCU issues, pointed by recent CI
improvements.
BPF:
- Put xsk sockets on a struct diet and add various cleanups. Overall,
this helps to bump performance by 12% for some workloads.
- Extend BPF selftests to increase coverage of XDP features in
combination with BPF cpumap.
- Optimize and homogenize bpf_csum_diff helper for all archs and also
add a batch of new BPF selftests for it.
- Extend netkit with an option to delegate skb->{mark,priority}
scrubbing to its BPF program.
- Make the bpf_get_netns_cookie() helper available also to tc(x) BPF
programs.
Protocols:
- Introduces 4-tuple hash for connected udp sockets, speeding-up
significantly connected sockets lookup.
- Add a fastpath for some TCP timers that usually expires after
close, the socket lock contention.
- Add inbound and outbound xfrm state caches to speed up state
lookups.
- Avoid sending MPTCP advertisements on stale subflows, reducing
risks on loosing them.
- Make neighbours table flushing more scalable, maintaining per
device neigh lists.
Driver API:
- Introduce a unified interface to configure transmission H/W
shaping, and expose it to user-space via generic-netlink.
- Add support for per-NAPI config via netlink. This makes napi
configuration persistent across queues removal and re-creation.
Requires driver updates, currently supported drivers are:
nVidia/Mellanox mlx4 and mlx5, Broadcom brcm and Intel ice.
- Add ethtool support for writing SFP / PHY firmware blocks.
- Track RSS context allocation from ethtool core.
- Implement support for mirroring to DSA CPU port, via TC mirror
offload.
- Consolidate FDB updates notification, to avoid duplicates on
device-specific entries.
- Expose DPLL clock quality level to the user-space.
- Support master-slave PHY config via device tree.
Tests and tooling:
- forwarding: introduce deferred commands, to simplify the cleanup
phase
Drivers:
- Updated several drivers - Amazon vNic, Google vNic, Microsoft vNic,
Intel e1000e and Broadcom Tigon3 - to use netdev-genl to link the
IRQs and queues to NAPI IDs, allowing busy polling and better
introspection.
- Ethernet high-speed NICs:
- nVidia/Mellanox:
- mlx5:
- a large refactor to implement support for cross E-Switch
scheduling
- refactor H/W conter management to let it scale better
- H/W GRO cleanups
- Intel (100G, ice)::
- add support for ethtool reset
- implement support for per TX queue H/W shaping
- AMD/Solarflare:
- implement per device queue stats support
- Broadcom (bnxt):
- improve wildcard l4proto on IPv4/IPv6 ntuple rules
- Marvell Octeon:
- Add representor support for each Resource Virtualization Unit
(RVU) device.
- Hisilicon:
- add support for the BMC Gigabit Ethernet
- IBM (EMAC):
- driver cleanup and modernization
- Cisco (VIC):
- raise the queues number limit to 256
- Ethernet virtual:
- Google vNIC:
- implement page pool support
- macsec:
- inherit lower device's features and TSO limits when
offloading
- virtio_net:
- enable premapped mode by default
- support for XDP socket(AF_XDP) zerocopy TX
- wireguard:
- set the TSO max size to be GSO_MAX_SIZE, to aggregate larger
packets.
- Ethernet NICs embedded and virtual:
- Broadcom ASP:
- enable software timestamping
- Freescale:
- add enetc4 PF driver
- MediaTek: Airoha SoC:
- implement BQL support
- RealTek r8169:
- enable TSO by default on r8168/r8125
- implement extended ethtool stats
- Renesas AVB:
- enable TX checksum offload
- Synopsys (stmmac):
- support header splitting for vlan tagged packets
- move common code for DWMAC4 and DWXGMAC into a separate FPE
module.
- add dwmac driver support for T-HEAD TH1520 SoC
- Synopsys (xpcs):
- driver refactor and cleanup
- TI:
- icssg_prueth: add VLAN offload support
- Xilinx emaclite:
- add clock support
- Ethernet switches:
- Microchip:
- implement support for the lan969x Ethernet switch family
- add LAN9646 switch support to KSZ DSA driver
- Ethernet PHYs:
- Marvel: 88q2x: enable auto negotiation
- Microchip: add support for LAN865X Rev B1 and LAN867X Rev C1/C2
- PTP:
- Add support for the Amazon virtual clock device
- Add PtP driver for s390 clocks
- WiFi:
- mac80211
- EHT 1024 aggregation size for transmissions
- new operation to indicate that a new interface is to be added
- support radio separation of multi-band devices
- move wireless extension spy implementation to libiw
- Broadcom:
- brcmfmac: optional LPO clock support
- Microchip:
- add support for Atmel WILC3000
- Qualcomm (ath12k):
- firmware coredump collection support
- add debugfs support for a multitude of statistics
- Qualcomm (ath5k):
- Arcadyan ARV45XX AR2417 & Gigaset SX76[23] AR241[34]A support
- Realtek:
- rtw88: 8821au and 8812au USB adapters support
- rtw89: add thermal protection
- rtw89: fine tune BT-coexsitence to improve user experience
- rtw89: firmware secure boot for WiFi 6 chip
- Bluetooth
- add Qualcomm WCN785x support for ids Foxconn 0xe0fc/0xe0f3 and
0x13d3:0x3623
- add Realtek RTL8852BE support for id Foxconn 0xe123
- add MediaTek MT7920 support for wireless module ids
- btintel_pcie: add handshake between driver and firmware
- btintel_pcie: add recovery mechanism
- btnxpuart: add GPIO support to power save feature"
* tag 'net-next-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1475 commits)
mm: page_frag: fix a compile error when kernel is not compiled
Documentation: tipc: fix formatting issue in tipc.rst
selftests: nic_performance: Add selftest for performance of NIC driver
selftests: nic_link_layer: Add selftest case for speed and duplex states
selftests: nic_link_layer: Add link layer selftest for NIC driver
bnxt_en: Add FW trace coredump segments to the coredump
bnxt_en: Add a new ethtool -W dump flag
bnxt_en: Add 2 parameters to bnxt_fill_coredump_seg_hdr()
bnxt_en: Add functions to copy host context memory
bnxt_en: Do not free FW log context memory
bnxt_en: Manage the FW trace context memory
bnxt_en: Allocate backing store memory for FW trace logs
bnxt_en: Add a 'force' parameter to bnxt_free_ctx_mem()
bnxt_en: Refactor bnxt_free_ctx_mem()
bnxt_en: Add mem_valid bit to struct bnxt_ctx_mem_type
bnxt_en: Update firmware interface spec to 1.10.3.85
selftests/bpf: Add some tests with sockmap SK_PASS
bpf: fix recursive lock when verdict program return SK_PASS
wireguard: device: support big tcp GSO
wireguard: selftests: load nf_conntrack if not present
...
|
||
|
Linus Torvalds
|
0f25f0e4ef |
the bulk of struct fd memory safety stuff
Making sure that struct fd instances are destroyed in the same
scope where they'd been created, getting rid of reassignments
and passing them by reference, converting to CLASS(fd{,_pos,_raw}).
We are getting very close to having the memory safety of that stuff
trivial to verify.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull 'struct fd' class updates from Al Viro:
"The bulk of struct fd memory safety stuff
Making sure that struct fd instances are destroyed in the same scope
where they'd been created, getting rid of reassignments and passing
them by reference, converting to CLASS(fd{,_pos,_raw}).
We are getting very close to having the memory safety of that stuff
trivial to verify"
* tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (28 commits)
deal with the last remaing boolean uses of fd_file()
css_set_fork(): switch to CLASS(fd_raw, ...)
memcg_write_event_control(): switch to CLASS(fd)
assorted variants of irqfd setup: convert to CLASS(fd)
do_pollfd(): convert to CLASS(fd)
convert do_select()
convert vfs_dedupe_file_range().
convert cifs_ioctl_copychunk()
convert media_request_get_by_fd()
convert spu_run(2)
switch spufs_calls_{get,put}() to CLASS() use
convert cachestat(2)
convert do_preadv()/do_pwritev()
fdget(), more trivial conversions
fdget(), trivial conversions
privcmd_ioeventfd_assign(): don't open-code eventfd_ctx_fdget()
o2hb_region_dev_store(): avoid goto around fdget()/fdput()
introduce "fd_pos" class, convert fdget_pos() users to it.
fdget_raw() users: switch to CLASS(fd_raw)
convert vmsplice() to CLASS(fd)
...
|
||
|
Linus Torvalds
|
4c797b11a8 |
vfs-6.13.file
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Merge tag 'vfs-6.13.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs file updates from Christian Brauner:
"This contains changes the changes for files for this cycle:
- Introduce a new reference counting mechanism for files.
As atomic_inc_not_zero() is implemented with a try_cmpxchg() loop
it has O(N^2) behaviour under contention with N concurrent
operations and it is in a hot path in __fget_files_rcu().
The rcuref infrastructures remedies this problem by using an
unconditional increment relying on safe- and dead zones to make
this work and requiring rcu protection for the data structure in
question. This not just scales better it also introduces overflow
protection.
However, in contrast to generic rcuref, files require a memory
barrier and thus cannot rely on *_relaxed() atomic operations and
also require to be built on atomic_long_t as having massive amounts
of reference isn't unheard of even if it is just an attack.
This adds a file specific variant instead of making this a generic
library.
This has been tested by various people and it gives consistent
improvement up to 3-5% on workloads with loads of threads.
- Add a fastpath for find_next_zero_bit(). Skip 2-levels searching
via find_next_zero_bit() when there is a free slot in the word that
contains the next fd. This improves pts/blogbench-1.1.0 read by 8%
and write by 4% on Intel ICX 160.
- Conditionally clear full_fds_bits since it's very likely that a bit
in full_fds_bits has been cleared during __clear_open_fds(). This
improves pts/blogbench-1.1.0 read up to 13%, and write up to 5% on
Intel ICX 160.
- Get rid of all lookup_*_fdget_rcu() variants. They were used to
lookup files without taking a reference count. That became invalid
once files were switched to SLAB_TYPESAFE_BY_RCU and now we're
always taking a reference count. Switch to an already existing
helper and remove the legacy variants.
- Remove pointless includes of <linux/fdtable.h>.
- Avoid cmpxchg() in close_files() as nobody else has a reference to
the files_struct at that point.
- Move close_range() into fs/file.c and fold __close_range() into it.
- Cleanup calling conventions of alloc_fdtable() and expand_files().
- Merge __{set,clear}_close_on_exec() into one.
- Make __set_open_fd() set cloexec as well instead of doing it in two
separate steps"
* tag 'vfs-6.13.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests: add file SLAB_TYPESAFE_BY_RCU recycling stressor
fs: port files to file_ref
fs: add file_ref
expand_files(): simplify calling conventions
make __set_open_fd() set cloexec state as well
fs: protect backing files with rcu
file.c: merge __{set,clear}_close_on_exec()
alloc_fdtable(): change calling conventions.
fs/file.c: add fast path in find_next_fd()
fs/file.c: conditionally clear full_fds
fs/file.c: remove sanity_check and add likely/unlikely in alloc_fd()
move close_range(2) into fs/file.c, fold __close_range() into it
close_files(): don't bother with xchg()
remove pointless includes of <linux/fdtable.h>
get rid of ...lookup...fdget_rcu() family
|
||
|
Martin Karsten
|
8a6de2627f |
eventpoll: Control irq suspension for prefer_busy_poll
When events are reported to userland and prefer_busy_poll is set, irqs are temporarily suspended using napi_suspend_irqs. If no events are found and ep_poll would go to sleep, irq suspension is cancelled using napi_resume_irqs. Signed-off-by: Martin Karsten <mkarsten@uwaterloo.ca> Co-developed-by: Joe Damato <jdamato@fastly.com> Signed-off-by: Joe Damato <jdamato@fastly.com> Tested-by: Joe Damato <jdamato@fastly.com> Tested-by: Martin Karsten <mkarsten@uwaterloo.ca> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com> Link: https://patch.msgid.link/20241109050245.191288-5-jdamato@fastly.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
||
|
Martin Karsten
|
ab5b28b007 |
eventpoll: Trigger napi_busy_loop, if prefer_busy_poll is set
Setting prefer_busy_poll now leads to an effectively nonblocking iteration though napi_busy_loop, even when busy_poll_usecs is 0. Signed-off-by: Martin Karsten <mkarsten@uwaterloo.ca> Co-developed-by: Joe Damato <jdamato@fastly.com> Signed-off-by: Joe Damato <jdamato@fastly.com> Tested-by: Joe Damato <jdamato@fastly.com> Tested-by: Martin Karsten <mkarsten@uwaterloo.ca> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com> Link: https://patch.msgid.link/20241109050245.191288-4-jdamato@fastly.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
||
|
Al Viro
|
8152f82010 |
fdget(), more trivial conversions
all failure exits prior to fdget() leave the scope, all matching fdput() are immediately followed by leaving the scope. [xfs_ioc_commit_range() chunk moved here as well] Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
||
|
Al Viro
|
6348be02ee |
fdget(), trivial conversions
fdget() is the first thing done in scope, all matching fdput() are immediately followed by leaving the scope. Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
||
|
Christian Brauner
|
90ee6ed776
|
fs: port files to file_ref
Port files to rely on file_ref reference to improve scaling and gain
overflow protection.
- We continue to WARN during get_file() in case a file that is already
marked dead is revived as get_file() is only valid if the caller
already holds a reference to the file. This hasn't changed just the
check changes.
- The semantics for epoll and ttm's dmabuf usage have changed. Both
epoll and ttm synchronize with __fput() to prevent the underlying file
from beeing freed.
(1) epoll
Explaining epoll is straightforward using a simple diagram.
Essentially, the mutex of the epoll instance needs to be taken in both
__fput() and around epi_fget() preventing the file from being freed
while it is polled or preventing the file from being resurrected.
CPU1 CPU2
fput(file)
-> __fput(file)
-> eventpoll_release(file)
-> eventpoll_release_file(file)
mutex_lock(&ep->mtx)
epi_item_poll()
-> epi_fget()
-> file_ref_get(file)
mutex_unlock(&ep->mtx)
mutex_lock(&ep->mtx);
__ep_remove()
mutex_unlock(&ep->mtx);
-> kmem_cache_free(file)
(2) ttm dmabuf
This explanation is a bit more involved. A regular dmabuf file stashed
the dmabuf in file->private_data and the file in dmabuf->file:
file->private_data = dmabuf;
dmabuf->file = file;
The generic release method of a dmabuf file handles file specific
things:
f_op->release::dma_buf_file_release()
while the generic dentry release method of a dmabuf handles dmabuf
freeing including driver specific things:
dentry->d_release::dma_buf_release()
During ttm dmabuf initialization in ttm_object_device_init() the ttm
driver copies the provided struct dma_buf_ops into a private location:
struct ttm_object_device {
spinlock_t object_lock;
struct dma_buf_ops ops;
void (*dmabuf_release)(struct dma_buf *dma_buf);
struct idr idr;
};
ttm_object_device_init(const struct dma_buf_ops *ops)
{
// copy original dma_buf_ops in private location
tdev->ops = *ops;
// stash the release method of the original struct dma_buf_ops
tdev->dmabuf_release = tdev->ops.release;
// override the release method in the copy of the struct dma_buf_ops
// with ttm's own dmabuf release method
tdev->ops.release = ttm_prime_dmabuf_release;
}
When a new dmabuf is created the struct dma_buf_ops with the overriden
release method set to ttm_prime_dmabuf_release is passed in exp_info.ops:
DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
exp_info.ops = &tdev->ops;
exp_info.size = prime->size;
exp_info.flags = flags;
exp_info.priv = prime;
The call to dma_buf_export() then sets
mutex_lock_interruptible(&prime->mutex);
dma_buf = dma_buf_export(&exp_info)
{
dmabuf->ops = exp_info->ops;
}
mutex_unlock(&prime->mutex);
which creates a new dmabuf file and then install a file descriptor to
it in the callers file descriptor table:
ret = dma_buf_fd(dma_buf, flags);
When that dmabuf file is closed we now get:
fput(file)
-> __fput(file)
-> f_op->release::dma_buf_file_release()
-> dput()
-> d_op->d_release::dma_buf_release()
-> dmabuf->ops->release::ttm_prime_dmabuf_release()
mutex_lock(&prime->mutex);
if (prime->dma_buf == dma_buf)
prime->dma_buf = NULL;
mutex_unlock(&prime->mutex);
Where we can see that prime->dma_buf is set to NULL. So when we have
the following diagram:
CPU1 CPU2
fput(file)
-> __fput(file)
-> f_op->release::dma_buf_file_release()
-> dput()
-> d_op->d_release::dma_buf_release()
-> dmabuf->ops->release::ttm_prime_dmabuf_release()
ttm_prime_handle_to_fd()
mutex_lock_interruptible(&prime->mutex)
dma_buf = prime->dma_buf
dma_buf && get_dma_buf_unless_doomed(dma_buf)
-> file_ref_get(dma_buf->file)
mutex_unlock(&prime->mutex);
mutex_lock(&prime->mutex);
if (prime->dma_buf == dma_buf)
prime->dma_buf = NULL;
mutex_unlock(&prime->mutex);
-> kmem_cache_free(file)
The logic of the mechanism is the same as for epoll: sync with
__fput() preventing the file from being freed. Here the
synchronization happens through the ttm instance's prime->mutex.
Basically, the lifetime of the dma_buf and the file are tighly
coupled.
Both (1) and (2) used to call atomic_inc_not_zero() to check whether
the file has already been marked dead and then refuse to revive it.
This is only safe because both (1) and (2) sync with __fput() and thus
prevent kmem_cache_free() on the file being called and thus prevent
the file from being immediately recycled due to SLAB_TYPESAFE_BY_RCU.
Both (1) and (2) have been ported from atomic_inc_not_zero() to
file_ref_get(). That means a file that is already in the process of
being marked as FILE_REF_DEAD:
file_ref_put()
cnt = atomic_long_dec_return()
-> __file_ref_put(cnt)
if (cnt == FIlE_REF_NOREF)
atomic_long_try_cmpxchg_release(cnt, FILE_REF_DEAD)
can be revived again:
CPU1 CPU2
file_ref_put()
cnt = atomic_long_dec_return()
-> __file_ref_put(cnt)
if (cnt == FIlE_REF_NOREF)
file_ref_get()
// Brings reference back to FILE_REF_ONEREF
atomic_long_add_negative()
atomic_long_try_cmpxchg_release(cnt, FILE_REF_DEAD)
This is fine and inherent to the file_ref_get()/file_ref_put()
semantics. For both (1) and (2) this is safe because __fput() is
prevented from making progress if file_ref_get() fails due to the
aforementioned synchronization mechanisms.
Two cases need to be considered that affect both (1) epoll and (2) ttm
dmabuf:
(i) fput()'s file_ref_put() and marks the file as FILE_REF_NOREF but
before that fput() can mark the file as FILE_REF_DEAD someone
manages to sneak in a file_ref_get() and brings the refcount back
from FILE_REF_NOREF to FILE_REF_ONEREF. In that case the original
fput() doesn't call __fput(). For epoll the poll will finish and
for ttm dmabuf the file can be used again. For ttm dambuf this is
actually an advantage because it avoids immediately allocating
a new dmabuf object.
CPU1 CPU2
file_ref_put()
cnt = atomic_long_dec_return()
-> __file_ref_put(cnt)
if (cnt == FIlE_REF_NOREF)
file_ref_get()
// Brings reference back to FILE_REF_ONEREF
atomic_long_add_negative()
atomic_long_try_cmpxchg_release(cnt, FILE_REF_DEAD)
(ii) fput()'s file_ref_put() marks the file FILE_REF_NOREF and
also suceeds in actually marking it FILE_REF_DEAD and then calls
into __fput() to free the file.
When either (1) or (2) call file_ref_get() they fail as
atomic_long_add_negative() will return true.
At the same time, both (1) and (2) all file_ref_get() under
mutexes that __fput() must also acquire preventing
kmem_cache_free() from freeing the file.
So while this might be treated as a change in semantics for (1) and
(2) it really isn't. It if should end up causing issues this can be
fixed by adding a helper that does something like:
long cnt = atomic_long_read(&ref->refcnt);
do {
if (cnt < 0)
return false;
} while (!atomic_long_try_cmpxchg(&ref->refcnt, &cnt, cnt + 1));
return true;
which would block FILE_REF_NOREF to FILE_REF_ONEREF transitions.
- Jann correctly pointed out that kmem_cache_zalloc() cannot be used
anymore once files have been ported to file_ref_t.
The kmem_cache_zalloc() call will memset() the whole struct file to
zero when it is reallocated. This will also set file->f_ref to zero
which mens that a concurrent file_ref_get() can return true:
CPU1 CPU2
__get_file_rcu()
rcu_dereference_raw()
close()
[frees file]
alloc_empty_file()
kmem_cache_zalloc()
[reallocates same file]
memset(..., 0, ...)
file_ref_get()
[increments 0->1, returns true]
init_file()
file_ref_init(..., 1)
[sets to 0]
rcu_dereference_raw()
fput()
file_ref_put()
[decrements 0->FILE_REF_NOREF, frees file]
[UAF]
causing a concurrent __get_file_rcu() call to acquire a reference to
the file that is about to be reallocated and immediately freeing it
on realizing that it has been recycled. This causes a UAF for the
task that reallocated/recycled the file.
This is prevented by switching from kmem_cache_zalloc() to
kmem_cache_alloc() and initializing the fields manually. With
file->f_ref initialized last.
Note that a memset() also isn't guaranteed to atomically update an
unsigned long so it's theoretically possible to see torn and
therefore bogus counter values.
Link: https://lore.kernel.org/r/20241007-brauner-file-rcuref-v2-3-387e24dc9163@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Xuewen Yan
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900bbaae67
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epoll: Add synchronous wakeup support for ep_poll_callback
Now, the epoll only use wake_up() interface to wake up task. However, sometimes, there are epoll users which want to use the synchronous wakeup flag to hint the scheduler, such as Android binder driver. So add a wake_up_sync() define, and use the wake_up_sync() when the sync is true in ep_poll_callback(). Co-developed-by: Jing Xia <jing.xia@unisoc.com> Signed-off-by: Jing Xia <jing.xia@unisoc.com> Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> Link: https://lore.kernel.org/r/20240426080548.8203-1-xuewen.yan@unisoc.com Tested-by: Brian Geffon <bgeffon@google.com> Reviewed-by: Brian Geffon <bgeffon@google.com> Reported-by: Benoit Lize <lizeb@google.com> Signed-off-by: Christian Brauner <brauner@kernel.org> |
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Christian Brauner
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6474353a5e
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epoll: annotate racy check
Epoll relies on a racy fastpath check during __fput() in eventpoll_release() to avoid the hit of pointlessly acquiring a semaphore. Annotate that race by using WRITE_ONCE() and READ_ONCE(). Link: https://lore.kernel.org/r/66edfb3c.050a0220.3195df.001a.GAE@google.com Link: https://lore.kernel.org/r/20240925-fungieren-anbauen-79b334b00542@brauner Reviewed-by: Jan Kara <jack@suse.cz> Reported-by: syzbot+3b6b32dc50537a49bb4a@syzkaller.appspotmail.com Signed-off-by: Christian Brauner <brauner@kernel.org> |
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Linus Torvalds
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f8ffbc365f |
struct fd layout change (and conversion to accessor helpers)
-----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQQqUNBr3gm4hGXdBJlZ7Krx/gZQ6wUCZvDNmgAKCRBZ7Krx/gZQ 63zrAP9vI0rf55v27twiabe9LnI7aSx5ckoqXxFIFxyT3dOYpQD/bPmoApnWDD3d 592+iDgLsema/H/0/CqfqlaNtDNY8Q0= =HUl5 -----END PGP SIGNATURE----- Merge tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull 'struct fd' updates from Al Viro: "Just the 'struct fd' layout change, with conversion to accessor helpers" * tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: add struct fd constructors, get rid of __to_fd() struct fd: representation change introduce fd_file(), convert all accessors to it. |
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Martin Karsten
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b9ca079dd6 |
eventpoll: Annotate data-race of busy_poll_usecs
A struct eventpoll's busy_poll_usecs field can be modified via a user
ioctl at any time. All reads of this field should be annotated with
READ_ONCE.
Fixes:
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Joe Damato
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4f98f380f4 |
eventpoll: Don't re-zero eventpoll fields
Remove redundant and unnecessary code.
ep_alloc uses kzalloc to create struct eventpoll, so there is no need to
set fields to defaults of 0. This was accidentally introduced in commit
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Al Viro
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1da91ea87a |
introduce fd_file(), convert all accessors to it.
For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
This commit converts (almost) all of f.file to
fd_file(f). It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).
NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).
[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Linus Torvalds
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4efaa5acf0 |
epoll: be better about file lifetimes
epoll can call out to vfs_poll() with a file pointer that may race with the last 'fput()'. That would make f_count go down to zero, and while the ep->mtx locking means that the resulting file pointer tear-down will be blocked until the poll returns, it means that f_count is already dead, and any use of it won't actually get a reference to the file any more: it's dead regardless. Make sure we have a valid ref on the file pointer before we call down to vfs_poll() from the epoll routines. Link: https://lore.kernel.org/lkml/0000000000002d631f0615918f1e@google.com/ Reported-by: syzbot+045b454ab35fd82a35fb@syzkaller.appspotmail.com Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |