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Tetsuo Handa 0f8d4d46ff mm: mmap_lock: replace get_memcg_path_buf() with on-stack buffer 
commit 7d6be67cfdd4a53cea7147313ca13c531e3a470f upstream.

Commit 2b5067a814 ("mm: mmap_lock: add tracepoints around lock
acquisition") introduced TRACE_MMAP_LOCK_EVENT() macro using
preempt_disable() in order to let get_mm_memcg_path() return a percpu
buffer exclusively used by normal, softirq, irq and NMI contexts
respectively.

Commit 832b507253 ("mm: mmap_lock: use local locks instead of disabling
preemption") replaced preempt_disable() with local_lock(&memcg_paths.lock)
based on an argument that preempt_disable() has to be avoided because
get_mm_memcg_path() might sleep if PREEMPT_RT=y.

But syzbot started reporting

  inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.

and

  inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.

messages, for local_lock() does not disable IRQ.

We could replace local_lock() with local_lock_irqsave() in order to
suppress these messages.  But this patch instead replaces percpu buffers
with on-stack buffer, for the size of each buffer returned by
get_memcg_path_buf() is only 256 bytes which is tolerable for allocating
from current thread's kernel stack memory.

Link: https://lkml.kernel.org/r/ef22d289-eadb-4ed9-863b-fbc922b33d8d@I-love.SAKURA.ne.jp
Reported-by: syzbot <syzbot+40905bca570ae6784745@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=40905bca570ae6784745
Fixes: 832b507253 ("mm: mmap_lock: use local locks instead of disabling preemption")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-08-03 08:49:30 +02:00
arch powerpc/xmon: Fix disassembly CPU feature checks 2024-08-03 08:49:22 +02:00
block block: initialize integrity buffer to zero before writing it to media 2024-08-03 08:48:53 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: aead,cipher - zeroize key buffer after use 2024-07-11 12:47:05 +02:00
Documentation cifs: fix setting SecurityFlags to true 2024-07-18 13:18:37 +02:00
drivers s390/dasd: fix error checks in dasd_copy_pair_store() 2024-08-03 08:49:29 +02:00
fs fs/ntfs3: Keep runs for $MFT::$ATTR_DATA and $MFT::$ATTR_BITMAP 2024-08-03 08:49:28 +02:00
include mm/hugetlb: fix possible recursive locking detected warning 2024-08-03 08:49:29 +02:00
init smp: Provide 'setup_max_cpus' definition on UP too 2024-06-16 13:41:42 +02:00
io_uring io_uring/sqpoll: work around a potential audit memory leak 2024-06-27 13:46:14 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Eliminate remaining "make W=1" warnings in kernel/bpf/btf.o 2024-08-03 08:49:09 +02:00
lib sbitmap: fix io hung due to race on sbitmap_word::cleared 2024-08-03 08:49:29 +02:00
LICENSES
mm mm: mmap_lock: replace get_memcg_path_buf() with on-stack buffer 2024-08-03 08:49:30 +02:00
net ipv4: Fix incorrect TOS in fibmatch route get reply 2024-08-03 08:49:24 +02:00
rust rust: macros: fix soundness issue in module! macro 2024-05-17 11:56:17 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:12:28 +01:00
scripts kconfig: remove wrong expr_trans_bool() 2024-07-25 09:49:11 +02:00
security landlock: Don't lose track of restrictions on cred_transfer 2024-08-03 08:49:29 +02:00
sound ASoC: amd: Adjust error handling in case of absent codec device 2024-08-03 08:49:21 +02:00
tools ipv4: Fix incorrect TOS in fibmatch route get reply 2024-08-03 08:49:24 +02:00
usr
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:46:21 +02:00
.clang-format
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add leah to 6.1 MAINTAINERS file 2024-05-17 11:56:16 +02:00
Makefile Linux 6.1.102 2024-07-27 11:32:20 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.