[moderation] [fs?] KCSAN: data-race in do_sendfile / do_sendfile (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8f6f76a6a29f Merge tag 'mm-nonmm-stable-2023-11-02-14-08' ..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=155ac413680000
kernel config: https://syzkaller.appspot.com/x/.config?x=bbdaf57f4e1c9873
dashboard link: https://syzkaller.appspot.com/bug?extid=6a6c4c031c65cb4a0704
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/550bfe2fc1e9/disk-8f6f76a6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/408a7fa51a6b/vmlinux-8f6f76a6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/724db48603a5/bzImage-8f6f76a6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6a6c4c...@syzkaller.appspotmail.com

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

write to 0xffff888107209540 of 8 bytes by task 1400 on cpu 1:
do_sendfile+0x799/0x980
__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

write to 0xffff888107209540 of 8 bytes by task 1402 on cpu 0:
do_sendfile+0x799/0x980
__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: 0x0000000000000000 -> 0x0000000000349000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1402 Comm: syz-executor.2 Not tainted 6.6.0-syzkaller-12401-g8f6f76a6a29f #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.