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

[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=10576e12e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac34c1f29a8029df
dashboard link: https://syzkaller.appspot.com/bug?extid=c736c1c2eaf6e7e4fce2
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+c736c1...@syzkaller.appspotmail.com

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

write to 0xffff88813b475318 of 8 bytes by task 19917 on cpu 1:
i_size_write include/linux/fs.h:932 [inline]
generic_write_end+0x94/0x230 fs/buffer.c:2291
fat_write_end+0x4e/0x160 fs/fat/inode.c:244
cont_expand_zero fs/buffer.c:2514 [inline]
cont_write_begin+0x2c0/0x690 fs/buffer.c:2572
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
generic_cont_expand_simple+0xa7/0x140 fs/buffer.c:2473
fat_cont_expand+0x3a/0x160 fs/fat/file.c:223
fat_setattr+0x2a9/0x840 fs/fat/file.c:513
notify_change+0x866/0x8e0 fs/attr.c:499
do_truncate+0x116/0x150 fs/open.c:66
do_sys_ftruncate+0x2ba/0x3b0 fs/open.c:194
__do_sys_ftruncate fs/open.c:205 [inline]
__se_sys_ftruncate fs/open.c:203 [inline]
__x64_sys_ftruncate+0x33/0x40 fs/open.c:203
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 0xffff88813b475318 of 8 bytes by task 19934 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+0xa1/0xd0 mm/filemap.c:420
sync_file_range+0x1b3/0x220 fs/sync.c:292
ksys_sync_file_range fs/sync.c:364 [inline]
__do_sys_sync_file_range fs/sync.c:373 [inline]
__se_sys_sync_file_range fs/sync.c:370 [inline]
__x64_sys_sync_file_range+0x80/0xd0 fs/sync.c:370
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: 0x000000000068f000 -> 0x0000000000690000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19934 Comm: syz-executor.4 Tainted: G W 6.7.0-rc4-syzkaller-00039-g9ace34a8e446 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================


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[syzbot]

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