KCSAN: data-race in ext4_writepages / xas_clear_mark (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d5beb314 Merge tag 'hyperv-fixes-signed' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=138ad543500000
kernel config: https://syzkaller.appspot.com/x/.config?x=cf114765a0c30afa
dashboard link: https://syzkaller.appspot.com/bug?extid=2075ece7f7faae0c842d
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linu...@kvack.org]

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+2075ec...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in ext4_writepages / xas_clear_mark

write to 0xffff88810d4ed384 of 4 bytes by task 15579 on cpu 0:
xa_mark_clear lib/xarray.c:75 [inline]
xas_clear_mark+0x16c/0x180 lib/xarray.c:921
__test_set_page_writeback+0x38e/0x5b0 mm/page-writeback.c:2806
ext4_bio_write_page+0xef/0xda0 fs/ext4/page-io.c:453
mpage_submit_page fs/ext4/inode.c:2092 [inline]
mpage_process_page_bufs+0x4f8/0x5e0 fs/ext4/inode.c:2206
mpage_prepare_extent_to_map+0x4d6/0x630 fs/ext4/inode.c:2618
ext4_writepages+0x674/0x1e30 fs/ext4/inode.c:2746
do_writepages+0x7b/0x150 mm/page-writeback.c:2352
__filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:422
file_write_and_wait_range+0x9f/0x120 mm/filemap.c:761
ext4_sync_file+0x105/0x6c0 fs/ext4/fsync.c:151
vfs_fsync_range+0x107/0x120 fs/sync.c:200
generic_write_sync include/linux/fs.h:2739 [inline]
ext4_buffered_write_iter+0x384/0x3d0 fs/ext4/file.c:278
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:1318 [inline]
__se_sys_sendfile64 fs/read_write.c:1304 [inline]
__x64_sys_sendfile64+0xf2/0x130 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 0xffff88810d4ed384 of 4 bytes by task 15575 on cpu 1:
xa_marked include/linux/xarray.h:416 [inline]
mapping_tagged include/linux/fs.h:488 [inline]
ext4_writepages+0x150/0x1e30 fs/ext4/inode.c:2660
do_writepages+0x7b/0x150 mm/page-writeback.c:2352
__filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:422
filemap_write_and_wait_range+0x8b/0x2a0 mm/filemap.c:655
__iomap_dio_rw+0x38c/0x9b0 fs/iomap/direct-io.c:489
iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:605
ext4_dio_write_iter fs/ext4/file.c:552 [inline]
ext4_file_write_iter+0xe06/0x1090 fs/ext4/file.c:662
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:1318 [inline]
__se_sys_sendfile64 fs/read_write.c:1304 [inline]
__x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1304
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: 15575 Comm: syz-executor.2 Not tainted 5.10.0-rc5-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.