KCSAN: data-race in iput / writeback_sb_inodes (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 31f02006 Merge tag 'char-misc-5.10-rc2' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1197462a500000
kernel config: https://syzkaller.appspot.com/x/.config?x=1dbf0ab7718f3df5
dashboard link: https://syzkaller.appspot.com/bug?extid=738021518a55e3fd2572
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+738021...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in iput / writeback_sb_inodes

read-write to 0xffff88810d5d3bd8 of 8 bytes by task 26 on cpu 0:
inode_sync_complete fs/fs-writeback.c:1210 [inline]
writeback_sb_inodes+0xb29/0x1020 fs/fs-writeback.c:1749
wb_writeback+0x27d/0x660 fs/fs-writeback.c:1894
wb_do_writeback+0x101/0x5d0 fs/fs-writeback.c:2039
wb_workfn+0xb8/0x410 fs/fs-writeback.c:2080
process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
worker_thread+0x635/0xb90 kernel/workqueue.c:2418
kthread+0x1fa/0x220 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff88810d5d3bd8 of 8 bytes by task 8457 on cpu 1:
iput+0x2e/0x510 fs/inode.c:1670
do_unlinkat+0x2c9/0x4d0 fs/namei.c:3903
__do_sys_unlink fs/namei.c:3943 [inline]
__se_sys_unlink fs/namei.c:3941 [inline]
__x64_sys_unlink+0x2c/0x30 fs/namei.c:3941
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8457 Comm: syz-executor.3 Not tainted 5.10.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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