KCSAN: data-race in ext4_handle_inode_extension / ext4_mpage

KCSAN: data-race in ext4_handle_inode_extension / ext4_mpage_readpages (2)
Status: moderation: reported on 2020/12/07 11:36
Reported-by: syzbot+2f45f0223f19969bdac8@syzkaller.appspotmail.com
First crash: 184d, last: 19d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in ext4_handle_inode_extension / ext4_mpage_readpages				4	229d	274d	0/17	closed as invalid on 2020/06/18 14:24

Sample crash report:

==================================================================
BUG: KCSAN: data-race in ext4_handle_inode_extension / ext4_mpage_readpages

write to 0xffff88810d9b27f0 of 8 bytes by task 15821 on cpu 1:
 i_size_write include/linux/fs.h:870 [inline]
 ext4_update_inode_size fs/ext4/ext4.h:3285 [inline]
 ext4_handle_inode_extension+0x226/0x550 fs/ext4/file.c:332
 ext4_dio_write_iter fs/ext4/file.c:558 [inline]
 ext4_file_write_iter+0xe48/0x1090 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

read to 0xffff88810d9b27f0 of 8 bytes by task 15829 on cpu 0:
 ext4_readpage_limit fs/ext4/readpage.c:219 [inline]
 ext4_mpage_readpages+0x44b/0x14c0 fs/ext4/readpage.c:265
 ext4_readahead+0x99/0xa0 fs/ext4/inode.c:3261
 read_pages+0xa0/0x6e0 mm/readahead.c:130
 page_cache_ra_unbounded+0x17d/0x4c0 mm/readahead.c:212
 ondemand_readahead+0x560/0x780 mm/readahead.c:267
 page_cache_sync_ra+0x1ab/0x1c0 mm/readahead.c:577
 page_cache_sync_readahead include/linux/pagemap.h:839 [inline]
 generic_file_buffered_read_get_pages+0x234/0xaf0 mm/filemap.c:2361
 generic_file_buffered_read+0x27f/0x9a0 mm/filemap.c:2481
 generic_file_read_iter+0x80/0x3d0 mm/filemap.c:2633
 ext4_file_read_iter+0x2d0/0x420 fs/ext4/file.c:74
 call_read_iter include/linux/fs.h:1895 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:788 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:867
 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: 15829 Comm: syz-executor.5 Not tainted 5.11.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (14):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2021/01/05 13:30	upstream	36bbbd0e	a0234d98	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/12/18 12:25	upstream	a409ed15	04201c06	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/11/14 04:39	upstream	9e6a39ea	1bf9a662	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/11/02 04:42	upstream	31f02006	8bc4594f	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/10/04 12:36	upstream	22fbc037	5ef9c291	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/09/23 10:17	upstream	805c6d3c	287cd75a	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/09/22 00:07	upstream	98477740	9e1fa68e	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/09/16 23:12	upstream	5925fa68	77507d02	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/09/11 03:34	upstream	581cb3a2	ac7ca78e	.config	log	report		adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/09/05 17:19	upstream	c70672d8	abf9ba4f	.config	log	report		adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/09/02 10:46	upstream	b765a32a	abf9ba4f	.config	log	report		adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/08/01 09:33	upstream	7dc6fd0f	8df85ed9	.config	log	report		adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/07/27 10:21	upstream	92ed3019	cb93dc6a	.config	log	report		adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/07/24 22:29	upstream	68845a55	554af388	.config	log	report		adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu