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Filename Latest commit message Latest commit date
Ryusuke Konishi 862ee4422c nilfs2: fix hang in nilfs_lookup_dirty_data_buffers()
commit 38296afe3c6ee07319e01bb249aa4bb47c07b534 upstream.

Syzbot reported a hang issue in migrate_pages_batch() called by mbind()
and nilfs_lookup_dirty_data_buffers() called in the log writer of nilfs2.

While migrate_pages_batch() locks a folio and waits for the writeback to
complete, the log writer thread that should bring the writeback to
completion picks up the folio being written back in
nilfs_lookup_dirty_data_buffers() that it calls for subsequent log
creation and was trying to lock the folio.  Thus causing a deadlock.

In the first place, it is unexpected that folios/pages in the middle of
writeback will be updated and become dirty.  Nilfs2 adds a checksum to
verify the validity of the log being written and uses it for recovery at
mount, so data changes during writeback are suppressed.  Since this is
broken, an unclean shutdown could potentially cause recovery to fail.

Investigation revealed that the root cause is that the wait for writeback
completion in nilfs_page_mkwrite() is conditional, and if the backing
device does not require stable writes, data may be modified without
waiting.

Fix these issues by making nilfs_page_mkwrite() wait for writeback to
finish regardless of the stable write requirement of the backing device.

Link: https://lkml.kernel.org/r/20240131145657.4209-1-konishi.ryusuke@gmail.com
Fixes: 1d1d1a7672 ("mm: only enforce stable page writes if the backing device requires it")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+ee2ae68da3b22d04cd8d@syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/00000000000047d819061004ad6c@google.com
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-02-23 08:25:12 +01:00
arch x86/mm/ident_map: Use gbpages only where full GB page should be mapped. 2024-02-23 08:25:12 +01:00
block blk-mq: fix IO hang from sbitmap wakeup race 2024-02-23 08:25:03 +01:00
certs
crypto crypto: api - Disallow identical driver names 2024-02-23 08:24:48 +01:00
Documentation net: sysfs: Fix /sys/class/net/<iface> path 2024-02-23 08:25:05 +01:00
drivers mmc: slot-gpio: Allow non-sleeping GPIO ro 2024-02-23 08:25:12 +01:00
fs nilfs2: fix hang in nilfs_lookup_dirty_data_buffers() 2024-02-23 08:25:12 +01:00
include hrtimer: Report offline hrtimer enqueue 2024-02-23 08:25:08 +01:00
init
ipc
kernel ring-buffer: Clean ring_buffer_poll_wait() error return 2024-02-23 08:25:12 +01:00
lib
LICENSES
mm mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again 2024-02-23 08:25:10 +01:00
net nfc: nci: free rx_data_reassembly skb on NCI device cleanup 2024-02-23 08:25:11 +01:00
samples
scripts kbuild: Fix changing ELF file type for output of gen_btf for big endian 2024-02-23 08:25:10 +01:00
security apparmor: avoid crash when parsed profile name is empty 2024-01-25 14:34:31 -08:00
sound ALSA: hda/conexant: Add quirk for SWS JS201D 2024-02-23 08:25:12 +01:00
tools selftests: net: avoid just another constant wait 2024-02-23 08:25:06 +01:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.268 2024-01-25 14:34:33 -08:00
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.