[moderation] [exfat?] KCSAN: data-race in __mpage_writepage / generic_file_direct_write (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 13d88ac54ddd Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12442ae0e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=f89e9ee49649fd75
dashboard link: https://syzkaller.appspot.com/bug?extid=7818c56a0d3cb5ff5f8b
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/ab6d9ea75ec1/disk-13d88ac5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/73fdd3041409/vmlinux-13d88ac5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7f8338cd20e2/bzImage-13d88ac5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7818c5...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __mpage_writepage / generic_file_direct_write

write to 0xffff8881083f4a00 of 8 bytes by task 6731 on cpu 1:
i_size_write include/linux/fs.h:932 [inline]
generic_file_direct_write+0x19d/0x1f0 mm/filemap.c:3870
__generic_file_write_iter+0xae/0x120 mm/filemap.c:3999
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:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881083f4a00 of 8 bytes by task 6732 on cpu 0:
i_size_read include/linux/fs.h:910 [inline]
__mpage_writepage+0xc0/0xd90 fs/mpage.c:488
write_cache_pages+0x38d/0x740 mm/page-writeback.c:2474
mpage_writepages+0x72/0xe0 fs/mpage.c:678
fat_writepages+0x24/0x30 fs/fat/inode.c:200
do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:387
__filemap_fdatawrite_range mm/filemap.c:420 [inline]
file_write_and_wait_range+0xf4/0x190 mm/filemap.c:778
__generic_file_fsync+0x4c/0x140 fs/libfs.c:1440
fat_file_fsync+0x4c/0x100 fs/fat/file.c:191
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:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x000000000003a200 -> 0x000000000003a400

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6732 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-15156-g13d88ac54ddd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
==================================================================


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[syzbot]

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