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Ryusuke Konishi bcb5016559 nilfs2: fix unexpected freezing of nilfs_segctor_sync()
commit 936184eadd upstream.

A potential and reproducible race issue has been identified where
nilfs_segctor_sync() would block even after the log writer thread writes a
checkpoint, unless there is an interrupt or other trigger to resume log
writing.

This turned out to be because, depending on the execution timing of the
log writer thread running in parallel, the log writer thread may skip
responding to nilfs_segctor_sync(), which causes a call to schedule()
waiting for completion within nilfs_segctor_sync() to lose the opportunity
to wake up.

The reason why waking up the task waiting in nilfs_segctor_sync() may be
skipped is that updating the request generation issued using a shared
sequence counter and adding an wait queue entry to the request wait queue
to the log writer, are not done atomically.  There is a possibility that
log writing and request completion notification by nilfs_segctor_wakeup()
may occur between the two operations, and in that case, the wait queue
entry is not yet visible to nilfs_segctor_wakeup() and the wake-up of
nilfs_segctor_sync() will be carried over until the next request occurs.

Fix this issue by performing these two operations simultaneously within
the lock section of sc_state_lock.  Also, following the memory barrier
guidelines for event waiting loops, move the call to set_current_state()
in the same location into the event waiting loop to ensure that a memory
barrier is inserted just before the event condition determination.

Link: https://lkml.kernel.org/r/20240520132621.4054-3-konishi.ryusuke@gmail.com
Fixes: 9ff05123e3 ("nilfs2: segment constructor")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: "Bai, Shuangpeng" <sjb7183@psu.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-06-16 13:28:30 +02:00
arch x86/tsc: Trust initial offset in architectural TSC-adjust MSRs 2024-06-16 13:28:30 +02:00
block block: prevent division by zero in blk_rq_stat_sum() 2024-04-13 12:51:38 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:11:22 +02:00
crypto Revert "crypto: api - Disallow identical driver names" 2024-05-02 16:18:35 +02:00
Documentation docs: kernel_include.py: Cope with docutils 0.21 2024-05-25 16:17:18 +02:00
drivers net: smc91x: Fix m68k kernel compilation for ColdFire CPU 2024-06-16 13:28:30 +02:00
fs nilfs2: fix unexpected freezing of nilfs_segctor_sync() 2024-06-16 13:28:30 +02:00
include xfrm: Preserve vlan tags for transport mode software GRO 2024-05-17 11:43:53 +02:00
init init: open /initrd.image with O_LARGEFILE 2024-04-13 12:51:36 +02:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:23:06 +01:00
kernel ring-buffer: Fix a race between readers and resize checks 2024-06-16 13:28:30 +02:00
lib dyndbg: fix old BUG_ON in >control parser 2024-05-17 11:43:55 +02:00
LICENSES
mm x86/mm/pat: fix VM_PAT handling in COW mappings 2024-04-13 12:51:40 +02:00
net net: fix out-of-bounds access in ops_init 2024-05-17 11:43:55 +02:00
samples media: rename VFL_TYPE_GRABBER to _VIDEO 2024-03-26 18:22:22 -04:00
scripts kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1 2024-04-13 12:51:26 +02:00
security smack: Handle SMACK64TRANSMUTE in smack_inode_setsecurity() 2024-04-13 12:51:22 +02:00
sound ALSA: line6: Zero-initialize message buffers 2024-05-17 11:43:51 +02:00
tools Revert "selftests: mm: fix map_hugetlb failure on 64K page size systems" 2024-05-25 16:17:17 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: async_pf: Cleanup kvm_setup_async_pf() 2024-05-02 16:18:32 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild
Kconfig
MAINTAINERS iio: stx104: Move to addac subdirectory 2023-08-30 16:27:12 +02:00
Makefile Linux 5.4.277 2024-05-25 16:17:18 +02:00
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.