KCSAN: data-race in __xa_set_mark / writeback_sb_inodes (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e87297fa Merge tag 'drm-fixes-2020-12-04' of git://anongit..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11c5c19d500000
kernel config: https://syzkaller.appspot.com/x/.config?x=c949fed53798f819
dashboard link: https://syzkaller.appspot.com/bug?extid=228fbd6131a379048fd0
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+228fbd...@syzkaller.appspotmail.com

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

write to 0xffff888028fab384 of 4 bytes by task 32051 on cpu 1:
xa_mark_set lib/xarray.c:69 [inline]
xas_set_mark lib/xarray.c:889 [inline]
__xa_set_mark+0x187/0x1b0 lib/xarray.c:1898
__set_page_dirty+0x17e/0x1d0 fs/buffer.c:609
mark_buffer_dirty+0x126/0x230 fs/buffer.c:1137
__block_commit_write fs/buffer.c:2084 [inline]
block_write_end+0x13d/0x230 fs/buffer.c:2162
generic_write_end+0x5b/0x250 fs/buffer.c:2176
ext4_da_write_end+0x59b/0x760 fs/ext4/inode.c:3102
generic_perform_write+0x23e/0x3a0 mm/filemap.c:3340
ext4_buffered_write_iter+0x2e5/0x3d0 fs/ext4/file.c:270
ext4_file_write_iter+0x45e/0x1090 fs/ext4/file.c:503
call_write_iter include/linux/fs.h:1903 [inline]
do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
do_iter_write+0x112/0x4b0 fs/read_write.c:866
vfs_iter_write+0x4c/0x70 fs/read_write.c:907
iter_file_splice_write+0x42a/0x780 fs/splice.c:686
do_splice_from fs/splice.c:764 [inline]
direct_splice_actor+0x80/0xa0 fs/splice.c:933
splice_direct_to_actor+0x345/0x650 fs/splice.c:888
do_splice_direct+0xf5/0x170 fs/splice.c:976
do_sendfile+0x5db/0xca0 fs/read_write.c:1257
__do_sys_sendfile64 fs/read_write.c:1312 [inline]
__se_sys_sendfile64 fs/read_write.c:1304 [inline]
__x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1304
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888028fab384 of 4 bytes by task 13948 on cpu 0:
xa_marked include/linux/xarray.h:416 [inline]
mapping_tagged include/linux/fs.h:488 [inline]
requeue_inode fs/fs-writeback.c:1409 [inline]
writeback_sb_inodes+0x91d/0x1020 fs/fs-writeback.c:1748
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+0x1fd/0x220 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13948 Comm: kworker/u4:7 Not tainted 5.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn (flush-8:0)
==================================================================


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[syzbot]

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