KCSAN: data-race in ondemand_readahead / ondemand

KCSAN: data-race in ondemand_readahead / ondemand_readahead (5)
Status: auto-closed as invalid on 2021/07/05 00:47
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 125d, last: 119d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in ondemand_readahead / ondemand_readahead (4)	1	163d	163d	0/22	auto-closed as invalid on 2021/05/21 19:40
upstream	KCSAN: data-race in ondemand_readahead / ondemand_readahead (2)	201	241d	402d	0/22	auto-closed as invalid on 2021/03/05 09:30
upstream	KCSAN: data-race in ondemand_readahead / ondemand_readahead	44	466d	679d	0/22	closed as invalid on 2020/06/18 14:24
upstream	KCSAN: data-race in ondemand_readahead / ondemand_readahead (3)	1	200d	200d	0/22	auto-closed as invalid on 2021/04/14 20:49

Sample crash report:

==================================================================
BUG: KCSAN: data-race in ondemand_readahead / ondemand_readahead

write to 0xffff888100865098 of 8 bytes by task 21154 on cpu 1:
 ondemand_readahead+0x25a/0x7b0 mm/readahead.c:527
 page_cache_sync_ra+0xaf/0xe0 mm/readahead.c:578
 page_cache_sync_readahead include/linux/pagemap.h:879 [inline]
 filemap_get_pages mm/filemap.c:2467 [inline]
 filemap_read+0x388/0x1230 mm/filemap.c:2550
 generic_file_read_iter+0x75/0x2c0 mm/filemap.c:2701
 ext4_file_read_iter+0x1db/0x290 fs/ext4/file.c:73
 call_read_iter include/linux/fs.h:2108 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888100865098 of 8 bytes by task 21161 on cpu 0:
 ondemand_readahead+0x172/0x7b0 mm/readahead.c:463
 page_cache_sync_ra+0xaf/0xe0 mm/readahead.c:578
 page_cache_sync_readahead include/linux/pagemap.h:879 [inline]
 filemap_get_pages mm/filemap.c:2467 [inline]
 filemap_read+0x388/0x1230 mm/filemap.c:2550
 generic_file_read_iter+0x75/0x2c0 mm/filemap.c:2701
 ext4_file_read_iter+0x1db/0x290 fs/ext4/file.c:73
 call_read_iter include/linux/fs.h:2108 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000838 -> 0x000000000000084d

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21161 Comm: syz-executor.4 Not tainted 5.13.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2021/05/31 00:41	upstream	8124c8a6b353	325a8dab	.config	log	report			info	KCSAN: data-race in ondemand_readahead / ondemand_readahead
ci2-upstream-kcsan-gce	2021/05/25 15:12	upstream	1434a3127887	3c7fef33	.config	log	report			info	KCSAN: data-race in ondemand_readahead / ondemand_readahead