KCSAN: data-race in __mark_inode_dirty / __writeback_single_inode (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6ad4bf6e Merge tag 'io_uring-5.10-2020-10-12' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=101ad320500000
kernel config: https://syzkaller.appspot.com/x/.config?x=749b0e51e8776ed1
dashboard link: https://syzkaller.appspot.com/bug?extid=dd7eafdc93343dca0f7d
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project.git ca2dcbd030eadbf0aa9b660efe864ff08af6e18b)
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+dd7eaf...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __mark_inode_dirty / __writeback_single_inode

write to 0xffff88811f1ba5c8 of 8 bytes by task 12481 on cpu 0:
__writeback_single_inode+0x256/0x580 fs/fs-writeback.c:1492
writeback_sb_inodes+0x6c0/0xfd0 fs/fs-writeback.c:1721
wb_writeback+0x28d/0x670 fs/fs-writeback.c:1894
wb_do_writeback+0x101/0x5d0 fs/fs-writeback.c:2039
wb_workfn+0xc8/0x430 fs/fs-writeback.c:2080
process_one_work+0x3e1/0x950 kernel/workqueue.c:2269
worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
kthread+0x20d/0x230 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88811f1ba5c8 of 8 bytes by task 16072 on cpu 1:
__mark_inode_dirty+0xb9/0x740 fs/fs-writeback.c:2274
mark_buffer_dirty+0x143/0x230 fs/buffer.c:1141
__block_commit_write fs/buffer.c:2084 [inline]
block_write_end+0x13d/0x220 fs/buffer.c:2162
generic_write_end+0x5c/0x250 fs/buffer.c:2176
ext4_da_write_end+0x58d/0x750 fs/ext4/inode.c:3091
generic_perform_write+0x23b/0x390 mm/filemap.c:3516
ext4_buffered_write_iter+0x2ce/0x3b0 fs/ext4/file.c:269
ext4_file_write_iter+0x49e/0x1060 include/linux/fs.h:779
call_write_iter include/linux/fs.h:1877 [inline]
new_sync_write fs/read_write.c:503 [inline]
vfs_write+0x654/0x6d0 fs/read_write.c:586
ksys_write+0xce/0x180 fs/read_write.c:639
__do_sys_write fs/read_write.c:651 [inline]
__se_sys_write fs/read_write.c:648 [inline]
__x64_sys_write+0x3e/0x50 fs/read_write.c:648
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: 16072 Comm: syz-executor.4 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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