[moderation] [exfat?] KCSAN: data-race in mark_buffer_dirty_inode / mark_buffer_dirty_inode (9)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c02197fc9076 Merge tag 'powerpc-6.8-3' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=107da064180000
kernel config: https://syzkaller.appspot.com/x/.config?x=35da3c2b3ebcd816
dashboard link: https://syzkaller.appspot.com/bug?extid=6f02a4c0330d4ca50cd0
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/87178b0f60b5/disk-c02197fc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3026549de711/vmlinux-c02197fc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3d434241850c/bzImage-c02197fc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6f02a4...@syzkaller.appspotmail.com

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

write to 0xffff888106aa14d0 of 8 bytes by task 4568 on cpu 1:
mark_buffer_dirty_inode+0x190/0x1c0 fs/buffer.c:684
fat_mirror_bhs+0x247/0x340 fs/fat/fatent.c:398
fat_alloc_clusters+0x973/0xa60 fs/fat/fatent.c:543
fat_add_cluster fs/fat/inode.c:108 [inline]
__fat_get_block fs/fat/inode.c:155 [inline]
fat_get_block+0x25c/0x5e0 fs/fat/inode.c:190
__block_write_begin_int+0x40b/0xf80 fs/buffer.c:2103
__block_write_begin fs/buffer.c:2152 [inline]
block_write_begin+0x7b/0x170 fs/buffer.c:2211
cont_write_begin+0x479/0x690 fs/buffer.c:2565
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
generic_perform_write+0x1c9/0x410 mm/filemap.c:3930
__generic_file_write_iter+0xa1/0x120 mm/filemap.c:4025
generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4051
call_write_iter include/linux/fs.h:2085 [inline]
iter_file_splice_write+0x5de/0x950 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x167/0x2c0 fs/splice.c:1164
splice_direct_to_actor+0x2fb/0x660 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x3b9/0x960 fs/read_write.c:1295
__do_sys_sendfile64 fs/read_write.c:1356 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0xbd/0x150 fs/read_write.c:1348
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888106aa14d0 of 8 bytes by task 4562 on cpu 0:
mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:680
fat_mirror_bhs+0x247/0x340 fs/fat/fatent.c:398
fat_ent_write+0xc6/0xe0 fs/fat/fatent.c:423
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+0x40b/0xf80 fs/buffer.c:2103
__block_write_begin fs/buffer.c:2152 [inline]
block_write_begin+0x7b/0x170 fs/buffer.c:2211
cont_write_begin+0x479/0x690 fs/buffer.c:2565
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
generic_perform_write+0x1c9/0x410 mm/filemap.c:3930
__generic_file_write_iter+0xa1/0x120 mm/filemap.c:4025
generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4051
call_write_iter include/linux/fs.h:2085 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0x760/0x8d0 fs/read_write.c:590
ksys_write+0xeb/0x1a0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:652
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000000 -> 0xffff888106ad8210

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4562 Comm: syz-executor.1 Not tainted 6.8.0-rc4-syzkaller-00410-gc02197fc9076 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================
syz-executor.1 (4562) used greatest stack depth: 11000 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.