[moderation] [exfat?] KCSAN: data-race in mark_buffer_dirty_inode / sync_mapping_buffers (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9ace34a8e446 Merge tag 'cgroup-for-6.7-rc4-fixes' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13a6c682e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac34c1f29a8029df
dashboard link: https://syzkaller.appspot.com/bug?extid=e78344287a01a6308bb3
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [hiro...@mail.parknet.co.jp linki...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org sj155...@samsung.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/955528ed37c5/disk-9ace34a8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ed03c0892611/vmlinux-9ace34a8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b4d56563956a/bzImage-9ace34a8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e78344...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in mark_buffer_dirty_inode / sync_mapping_buffers

write to 0xffff888126fac400 of 8 bytes by task 5910 on cpu 1:
__remove_assoc_queue fs/buffer.c:517 [inline]
fsync_buffers_list fs/buffer.c:785 [inline]
sync_mapping_buffers+0x165/0x7d0 fs/buffer.c:578
fat_file_fsync+0xad/0x100 fs/fat/file.c:195
vfs_fsync_range+0x111/0x120 fs/sync.c:188
generic_write_sync include/linux/fs.h:2653 [inline]
generic_file_write_iter+0x191/0x1c0 mm/filemap.c:4043
do_iter_write+0x4ad/0x770 fs/read_write.c:860
vfs_iter_write+0x56/0x70 fs/read_write.c:901
iter_file_splice_write+0x462/0x7e0 fs/splice.c:736
do_splice_from fs/splice.c:933 [inline]
direct_splice_actor+0x8a/0xb0 fs/splice.c:1142
splice_direct_to_actor+0x31d/0x690 fs/splice.c:1088
do_splice_direct+0x10d/0x190 fs/splice.c:1194
do_sendfile+0x3c4/0x980 fs/read_write.c:1254
__do_sys_sendfile64 fs/read_write.c:1322 [inline]
__se_sys_sendfile64 fs/read_write.c:1308 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
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 0xffff888126fac400 of 8 bytes by task 5915 on cpu 0:
mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:681
fat16_ent_put+0x4f/0x60 fs/fat/fatent.c:184
fat_ent_write+0x62/0xe0 fs/fat/fatent.c:417
fat_chain_add+0x15f/0x400 fs/fat/misc.c:136
fat_add_cluster fs/fat/inode.c:113 [inline]
__fat_get_block fs/fat/inode.c:155 [inline]
fat_get_block+0x467/0x5e0 fs/fat/inode.c:190
__block_write_begin_int+0x3b7/0xf40 fs/buffer.c:2119
__block_write_begin fs/buffer.c:2168 [inline]
block_write_begin+0x7b/0x170 fs/buffer.c:2227
cont_write_begin+0x479/0x690 fs/buffer.c:2582
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
generic_perform_write+0x1c9/0x410 mm/filemap.c:3918
__generic_file_write_iter+0xa1/0x120 mm/filemap.c:4013
generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4039
do_iter_write+0x4ad/0x770 fs/read_write.c:860
vfs_iter_write+0x56/0x70 fs/read_write.c:901
iter_file_splice_write+0x462/0x7e0 fs/splice.c:736
do_splice_from fs/splice.c:933 [inline]
direct_splice_actor+0x8a/0xb0 fs/splice.c:1142
splice_direct_to_actor+0x31d/0x690 fs/splice.c:1088
do_splice_direct+0x10d/0x190 fs/splice.c:1194
do_sendfile+0x3c4/0x980 fs/read_write.c:1254
__do_sys_sendfile64 fs/read_write.c:1322 [inline]
__se_sys_sendfile64 fs/read_write.c:1308 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
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

value changed: 0xffff888106b18518 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5915 Comm: syz-executor.5 Not tainted 6.7.0-rc4-syzkaller-00039-g9ace34a8e446 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================
syz-executor.5 (5915) used greatest stack depth: 10344 bytes left


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[syzbot]

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