KCSAN: data-race in __writeback_single_inode / xas_clear

KCSAN: data-race in __writeback_single_inode / xas_clear_mark (4)
Status: auto-closed as invalid on 2020/11/02 04:03
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 303d, last: 303d

similar bugs (3):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __writeback_single_inode / xas_clear_mark (2)	5	544d	609d	0/22	auto-closed as invalid on 2020/04/10 19:48
upstream	KCSAN: data-race in __writeback_single_inode / xas_clear_mark (3)	1	338d	338d	0/22	auto-closed as invalid on 2020/09/27 22:17
upstream	KCSAN: data-race in __writeback_single_inode / xas_clear_mark	3	633d	644d	0/22	closed as invalid on 2019/11/19 13:24

Sample crash report:

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

write to 0xffff88812028c7f4 of 4 bytes by task 2913 on cpu 1:
 xa_mark_clear lib/xarray.c:75 [inline]
 xas_clear_mark+0x15a/0x170 lib/xarray.c:918
 __test_set_page_writeback+0x396/0x480 mm/page-writeback.c:2806
 ext4_bio_write_page+0xed/0xda0 fs/ext4/page-io.c:453
 mpage_submit_page fs/ext4/inode.c:2081 [inline]
 mpage_process_page_bufs+0x4f5/0x600 fs/ext4/inode.c:2195
 mpage_prepare_extent_to_map+0x4ec/0x650 fs/ext4/inode.c:2607
 ext4_writepages+0x682/0x1ed0 fs/ext4/inode.c:2735
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19b/0x1d0 mm/filemap.c:422
 file_write_and_wait_range+0x9f/0x120 mm/filemap.c:761
 ext4_sync_file+0xfc/0x6e0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2747 [inline]
 ext4_buffered_write_iter+0x369/0x3b0 fs/ext4/file.c:276
 ext4_file_write_iter+0x768/0x1060 include/linux/fs.h:784
 call_write_iter include/linux/fs.h:1882 [inline]
 do_iter_readv_writev+0x32e/0x3d0 fs/read_write.c:713
 do_iter_write+0x112/0x4b0 fs/read_write.c:1018
 vfs_iter_write+0x4c/0x70 fs/read_write.c:1059
 iter_file_splice_write+0x41a/0x770 fs/splice.c:750
 do_splice_from fs/splice.c:846 [inline]
 direct_splice_actor+0x95/0x160 fs/splice.c:1016
 splice_direct_to_actor+0x365/0x660 fs/splice.c:971
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x56a/0xba0 fs/read_write.c:1540
 __do_sys_sendfile64 fs/read_write.c:1595 [inline]
 __se_sys_sendfile64 fs/read_write.c:1587 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1587
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812028c7f4 of 4 bytes by task 2921 on cpu 0:
 xa_marked include/linux/xarray.h:416 [inline]
 mapping_tagged include/linux/fs.h:493 [inline]
 __writeback_single_inode+0x26d/0x600 fs/fs-writeback.c:1507
 writeback_single_inode+0x11f/0x580 fs/fs-writeback.c:1570
 sync_inode fs/fs-writeback.c:2605 [inline]
 sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2625
 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
 ext4_sync_file+0x335/0x6e0 fs/ext4/fsync.c:170
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2747 [inline]
 ext4_buffered_write_iter+0x369/0x3b0 fs/ext4/file.c:276
 ext4_file_write_iter+0x768/0x1060 include/linux/fs.h:784
 call_write_iter include/linux/fs.h:1882 [inline]
 do_iter_readv_writev+0x32e/0x3d0 fs/read_write.c:713
 do_iter_write+0x112/0x4b0 fs/read_write.c:1018
 vfs_iter_write+0x4c/0x70 fs/read_write.c:1059
 iter_file_splice_write+0x41a/0x770 fs/splice.c:750
 do_splice_from fs/splice.c:846 [inline]
 direct_splice_actor+0x95/0x160 fs/splice.c:1016
 splice_direct_to_actor+0x365/0x660 fs/splice.c:971
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x56a/0xba0 fs/read_write.c:1540
 __do_sys_sendfile64 fs/read_write.c:1595 [inline]
 __se_sys_sendfile64 fs/read_write.c:1587 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1587
 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: 0 PID: 2921 Comm: syz-executor.0 Not tainted 5.9.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/09/28 03:57	upstream	a1b8638ba132	5dd8aee8	.config	log	report			info