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proc/task_mmu: remove unnecessary helpers

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Patch series "read proc/pid/smaps_rollup under per-vma lock", v5.

proc/pid/smaps_rollup can be read using the combination of RCU and VMA
read locks, similar to proc/pid/{maps|smaps|numa_maps}.  RCU is required
to safely traverse the VMA tree and VMA lock stabilizes the VMA being
processed and the pagetable walk.  Note that we have to keep the logic to
drop mmap_lock on contention because even when using per-VMA locks we
might have to fall back to holding the mmap_lock.

The first 5 patches are cleanups making later change simpler.  The main
change is in patch 6.  Patch 7 extends existing proc-maps-race tearing
test to verify smaps_rollup content.


This patch (of 7):

When per-vma locks were behind a config option, a number of helper
functions were needed to simplify the locking code.  Now that these locks
are universally available, we can do a little cleanup.  Remove
lock_vma_range(), unlock_vma_range(), query_vma_setup(),
query_vma_teardown() helpers.

No functional change intended.

Link: https://lore.kernel.org/20260918153318.758387-1-surenb@google.com
Link: https://lore.kernel.org/20260918153318.758387-2-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Liam R. Howlett (Oracle) <liam@infradead.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: Usama Arif <usama.arif@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
This commit is contained in:
Suren Baghdasaryan 2026-09-18 08:33:12 -07:00 committed by Andrew Morton
parent 23fac055c2
commit 87ee17d24a
1 changed files with 17 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

67
fs/proc/task_mmu.c
View File

@ -160,25 +160,6 @@ static void unlock_ctx_vma(struct proc_maps_locking_ctx *lock_ctx)
}
}
static inline bool lock_vma_range(struct seq_file *m,
struct proc_maps_locking_ctx *lock_ctx)
{
rcu_read_lock();
reset_lock_ctx(lock_ctx);
return true;
}
static inline void unlock_vma_range(struct proc_maps_locking_ctx *lock_ctx)
{
if (lock_ctx->mmap_locked) {
unlock_ctx_mm(lock_ctx);
} else {
unlock_ctx_vma(lock_ctx);
rcu_read_unlock();
}
}
static struct vm_area_struct *get_next_vma(struct proc_maps_private *priv,
loff_t last_pos)
{
@ -286,13 +267,8 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
return NULL;
}
if (!lock_vma_range(m, lock_ctx)) {
mmput(mm);
put_task_struct(priv->task);
priv->task = NULL;
return ERR_PTR(-EINTR);
}
rcu_read_lock();
reset_lock_ctx(lock_ctx);
/*
* Reset current position if last_addr was set before
* and it's not a sentinel.
@ -325,7 +301,12 @@ static void m_stop(struct seq_file *m, void *v)
return;
release_task_mempolicy(priv);
unlock_vma_range(&priv->lock_ctx);
if (priv->lock_ctx.mmap_locked) {
unlock_ctx_mm(&priv->lock_ctx);
} else {
unlock_ctx_vma(&priv->lock_ctx);
rcu_read_unlock();
}
mmput(mm);
put_task_struct(priv->task);
priv->task = NULL;
@ -518,21 +499,6 @@ static int pid_maps_open(struct inode *inode, struct file *file)
PROCMAP_QUERY_VMA_FLAGS \
)
static int query_vma_setup(struct proc_maps_locking_ctx *lock_ctx)
{
reset_lock_ctx(lock_ctx);
return 0;
}
static void query_vma_teardown(struct proc_maps_locking_ctx *lock_ctx)
{
if (lock_ctx->mmap_locked)
unlock_ctx_mm(lock_ctx);
else
unlock_ctx_vma(lock_ctx);
}
static struct vm_area_struct *query_vma_find_by_addr(struct proc_maps_locking_ctx *lock_ctx,
unsigned long addr)
{
@ -653,12 +619,7 @@ static int do_procmap_query(struct mm_struct *mm, void __user *uarg)
if (!mm || !mmget_not_zero(mm))
return -ESRCH;
err = query_vma_setup(&lock_ctx);
if (err) {
mmput(mm);
return err;
}
reset_lock_ctx(&lock_ctx);
vma = query_matching_vma(&lock_ctx, karg.query_addr, karg.query_flags);
if (IS_ERR(vma)) {
err = PTR_ERR(vma);
@ -732,7 +693,10 @@ static int do_procmap_query(struct mm_struct *mm, void __user *uarg)
vm_file = get_file(vma->vm_file);
/* unlock vma or mmap_lock, and put mm_struct before copying data to user */
query_vma_teardown(&lock_ctx);
if (lock_ctx.mmap_locked)
unlock_ctx_mm(&lock_ctx);
else
unlock_ctx_vma(&lock_ctx);
mmput(mm);
if (karg.build_id_size) {
@ -773,7 +737,10 @@ static int do_procmap_query(struct mm_struct *mm, void __user *uarg)
return 0;
out:
query_vma_teardown(&lock_ctx);
if (lock_ctx.mmap_locked)
unlock_ctx_mm(&lock_ctx);
else
unlock_ctx_vma(&lock_ctx);
mmput(mm);
out_file:
if (vm_file)