KCSAN: data-race in ext4_writepages / xas_clear

KCSAN: data-race in ext4_writepages / xas_clear_mark (5)
Status: moderation: reported on 2020/12/07 11:55
Reported-by: syzbot+2075ece7f7faae0c842d@syzkaller.appspotmail.com
First crash: 73d, last: 5d00h

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in ext4_writepages / xas_clear_mark (4)	5	128d	195d	0/17	auto-closed as invalid on 2020/10/24 01:56
upstream	KCSAN: data-race in ext4_writepages / xas_clear_mark (3)	1	261d	261d	0/17	auto-closed as invalid on 2020/06/18 13:43
upstream	KCSAN: data-race in ext4_writepages / xas_clear_mark	3	452d	458d	0/17	closed as invalid on 2019/11/19 13:24
upstream	KCSAN: data-race in ext4_writepages / xas_clear_mark (2)	1	403d	403d	0/17	auto-closed as invalid on 2020/02/26 13:18

Sample crash report:

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

write to 0xffff88810870ccc4 of 4 bytes by task 8147 on cpu 1:
 xa_mark_clear lib/xarray.c:75 [inline]
 xas_clear_mark+0x16c/0x180 lib/xarray.c:921
 __test_set_page_writeback+0x3db/0x4d0 mm/page-writeback.c:2802
 ext4_bio_write_page+0xfe/0xe70 fs/ext4/page-io.c:450
 mpage_submit_page fs/ext4/inode.c:2101 [inline]
 mpage_process_page_bufs+0x4db/0x5d0 fs/ext4/inode.c:2215
 mpage_prepare_extent_to_map+0x4d6/0x630 fs/ext4/inode.c:2627
 ext4_writepages+0x674/0x1e50 fs/ext4/inode.c:2755
 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+0x105/0x6e0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2737 [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:1901 [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 0xffff88810870ccc4 of 4 bytes by task 8144 on cpu 0:
 xa_marked include/linux/xarray.h:416 [inline]
 mapping_tagged include/linux/fs.h:488 [inline]
 ext4_writepages+0x150/0x1e50 fs/ext4/inode.c:2669
 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:1901 [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: 0 PID: 8144 Comm: syz-executor.4 Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (8):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2021/01/20 06:14	upstream	45dfb8a5	63631df1	.config	log	report	info	akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
ci2-upstream-kcsan-gce	2021/01/10 22:33	upstream	0653161f	2c1f2513	.config	log	report	info	akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
ci2-upstream-kcsan-gce	2021/01/04 19:28	upstream	36bbbd0e	79264ae3	.config	log	report	info	akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
ci2-upstream-kcsan-gce	2020/12/28 21:24	upstream	c76e02c5	8259d56c	.config	log	report	info	akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
ci2-upstream-kcsan-gce	2020/12/26 12:26	upstream	40f78232	821e0b09	.config	log	report	info	akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
ci2-upstream-kcsan-gce	2020/12/19 01:16	upstream	3644e2d2	04201c06	.config	log	report	info	akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
ci2-upstream-kcsan-gce	2020/11/24 16:51	upstream	d5beb314	e34b696c	.config	log	report	info	akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
ci2-upstream-kcsan-gce	2020/11/12 11:11	upstream	3d5e28bf	77a55c8e	.config	log	report	info	akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org