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a2a3fa5b61
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Paolo Bonzini a2a3fa5b61 x86, kvm: use correct GFP flags for preemption disabled 
commit baec4f5a01 upstream.

Commit ddd7ed842627 ("x86/kvm: Alloc dummy async #PF token outside of
raw spinlock") leads to the following Smatch static checker warning:

	arch/x86/kernel/kvm.c:212 kvm_async_pf_task_wake()
	warn: sleeping in atomic context

arch/x86/kernel/kvm.c
    202         raw_spin_lock(&b->lock);
    203         n = _find_apf_task(b, token);
    204         if (!n) {
    205                 /*
    206                  * Async #PF not yet handled, add a dummy entry for the token.
    207                  * Allocating the token must be down outside of the raw lock
    208                  * as the allocator is preemptible on PREEMPT_RT kernels.
    209                  */
    210                 if (!dummy) {
    211                         raw_spin_unlock(&b->lock);
--> 212                         dummy = kzalloc(sizeof(*dummy), GFP_KERNEL);
                                                                ^^^^^^^^^^
Smatch thinks the caller has preempt disabled.  The `smdb.py preempt
kvm_async_pf_task_wake` output call tree is:

sysvec_kvm_asyncpf_interrupt() <- disables preempt
-> __sysvec_kvm_asyncpf_interrupt()
   -> kvm_async_pf_task_wake()

The caller is this:

arch/x86/kernel/kvm.c
   290        DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
   291        {
   292                struct pt_regs *old_regs = set_irq_regs(regs);
   293                u32 token;
   294
   295                ack_APIC_irq();
   296
   297                inc_irq_stat(irq_hv_callback_count);
   298
   299                if (__this_cpu_read(apf_reason.enabled)) {
   300                        token = __this_cpu_read(apf_reason.token);
   301                        kvm_async_pf_task_wake(token);
   302                        __this_cpu_write(apf_reason.token, 0);
   303                        wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
   304                }
   305
   306                set_irq_regs(old_regs);
   307        }

The DEFINE_IDTENTRY_SYSVEC() is a wrapper that calls this function
from the call_on_irqstack_cond().  It's inside the call_on_irqstack_cond()
where preempt is disabled (unless it's already disabled).  The
irq_enter/exit_rcu() functions disable/enable preempt.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-06-06 08:42:43 +02:00
arch x86, kvm: use correct GFP flags for preemption disabled 2022-06-06 08:42:43 +02:00
block block-map: add __GFP_ZERO flag for alloc_page in function bio_copy_kern 2022-05-12 12:25:45 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: drbg - make reseeding from get_random_bytes() synchronous 2022-06-06 08:42:42 +02:00
Documentation random: fix sysctl documentation nits 2022-05-30 09:33:40 +02:00
drivers crypto: drbg - make reseeding from get_random_bytes() synchronous 2022-06-06 08:42:42 +02:00
fs exfat: check if cluster num is valid 2022-06-06 08:42:42 +02:00
include netfilter: conntrack: re-fetch conntrack after insertion 2022-06-06 08:42:43 +02:00
init random: handle latent entropy and command line from random_init() 2022-05-30 09:33:44 +02:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:19:10 +01:00
kernel timekeeping: Add raw clock fallback for random_get_entropy() 2022-05-30 09:33:41 +02:00
lib lib/crypto: add prompts back to crypto libraries 2022-06-06 08:42:42 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm random: move randomize_page() into mm where it belongs 2022-05-30 09:33:45 +02:00
net netfilter: nf_tables: sanitize nft_set_desc_concat_parse() 2022-06-06 08:42:42 +02:00
samples samples/bpf, xdpsock: Fix race when running for fix duration of time 2022-04-08 14:40:21 +02:00
scripts gcc-plugins: latent_entropy: use /dev/urandom 2022-04-20 09:23:26 +02:00
security lockdown: also lock down previous kgdb use 2022-05-30 09:33:22 +02:00
sound ALSA: ctxfi: Add SB046x PCI ID 2022-05-30 09:33:45 +02:00
tools selftests: add ping test with ping_group_range tuned 2022-05-25 09:18:00 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt KVM: Prevent module exit until all VMs are freed 2022-04-08 14:40:38 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add git tree for random.c 2022-05-30 09:33:24 +02:00
Makefile Linux 5.10.119 2022-05-30 09:33:46 +02:00
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.