[moderation] [exfat?] KCSAN: data-race in filemap_splice_read / generic_write_end

[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=151546dae80000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac34c1f29a8029df
dashboard link: https://syzkaller.appspot.com/bug?extid=8409c96b66a5fb97dc0a
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+8409c9...@syzkaller.appspotmail.com

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

write to 0xffff888107f81928 of 8 bytes by task 16476 on cpu 0:
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
generic_perform_write+0x267/0x410 mm/filemap.c:3929
__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:1316 [inline]
__se_sys_sendfile64 fs/read_write.c:1308 [inline]
__x64_sys_sendfile64+0xbd/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 0xffff888107f81928 of 8 bytes by task 16478 on cpu 1:
i_size_read include/linux/fs.h:910 [inline]
filemap_splice_read+0x67b/0x7f0 mm/filemap.c:2856
vfs_splice_read fs/splice.c:993 [inline]
splice_direct_to_actor+0x28c/0x690 fs/splice.c:1069
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: 0x0000000000003a3e -> 0x0000000000003a54

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16478 Comm: syz-executor.3 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.