[moderation] [fs?] [mm?] KCSAN: data-race in xas_create / xas_find_marked (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f016f7547aee Merge tag 'gpio-fixes-for-v6.7-rc8' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11bb37e9e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=4da1e2da456c3a7d
dashboard link: https://syzkaller.appspot.com/bug?extid=d99a3b7070791d35415f
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@kvack.org wi...@infradead.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e9b1b541fff3/disk-f016f754.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bdb2cd0b408d/vmlinux-f016f754.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a2b71015010c/bzImage-f016f754.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d99a3b...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in xas_create / xas_find_marked

write to 0xffff888125cfa921 of 1 bytes by task 3505 on cpu 1:
xas_expand lib/xarray.c:612 [inline]
xas_create+0x656/0xbb0 lib/xarray.c:653
xas_store+0x78/0xc90 lib/xarray.c:787
__filemap_add_folio+0x45e/0x730 mm/filemap.c:898
filemap_add_folio+0x70/0x160 mm/filemap.c:937
page_cache_ra_unbounded+0x15e/0x2e0 mm/readahead.c:250
do_page_cache_ra mm/readahead.c:299 [inline]
force_page_cache_ra mm/readahead.c:330 [inline]
page_cache_sync_ra+0x24b/0x2a0 mm/readahead.c:691
page_cache_sync_readahead include/linux/pagemap.h:1283 [inline]
filemap_get_pages+0x251/0xf90 mm/filemap.c:2497
filemap_read+0x214/0x680 mm/filemap.c:2593
blkdev_read_iter+0x217/0x2c0 block/fops.c:742
call_read_iter include/linux/fs.h:2014 [inline]
new_sync_read fs/read_write.c:389 [inline]
vfs_read+0x3c0/0x590 fs/read_write.c:470
ksys_read+0xeb/0x1a0 fs/read_write.c:613
__do_sys_read fs/read_write.c:623 [inline]
__se_sys_read fs/read_write.c:621 [inline]
__x64_sys_read+0x42/0x50 fs/read_write.c:621
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888125cfa921 of 1 bytes by task 4285 on cpu 0:
xas_find_marked+0x419/0x660 lib/xarray.c:1338
find_get_entry+0x5d/0x290 mm/filemap.c:1960
filemap_get_folios_tag+0x136/0x210 mm/filemap.c:2210
write_cache_pages+0x20d/0x740 mm/page-writeback.c:2429
do_writepages+0x20f/0x340 mm/page-writeback.c:2558
filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:387
__filemap_fdatawrite_range mm/filemap.c:420 [inline]
__filemap_fdatawrite mm/filemap.c:426 [inline]
filemap_flush+0x95/0xc0 mm/filemap.c:453
sync_blockdev_nowait+0x36/0x50 block/bdev.c:186
sync_filesystem+0xe0/0x180 fs/sync.c:60
generic_shutdown_super+0x42/0x210 fs/super.c:669
kill_block_super+0x2a/0x60 fs/super.c:1667
ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7330
deactivate_locked_super+0x7a/0x1c0 fs/super.c:484
deactivate_super+0x9b/0xb0 fs/super.c:517
cleanup_mnt+0x272/0x2e0 fs/namespace.c:1256
__cleanup_mnt+0x19/0x20 fs/namespace.c:1263
task_work_run+0x135/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xd6/0xe0 kernel/entry/common.c:171
exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:296
do_syscall_64+0x50/0x110 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x32 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4285 Comm: syz-executor.4 Not tainted 6.7.0-rc7-syzkaller-00041-gf016f7547aee #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
==================================================================
EXT4-fs unmount: 1073 callbacks suppressed
EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.