KCSAN: data-race in nilfs_detach_log_writer / nilfs_segctor

KCSAN: data-race in nilfs_detach_log_writer / nilfs_segctor_thread
Status: auto-closed as invalid on 2020/12/01 14:00
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 275d, last: 275d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in nilfs_detach_log_writer / nilfs_segctor_thread (2)				21	109d	232d	0/22	auto-closed as invalid on 2021/05/17 11:36

Sample crash report:

==================================================================
BUG: KCSAN: data-race in nilfs_detach_log_writer / nilfs_segctor_thread

write to 0xffff8880224d89e8 of 8 bytes by task 15117 on cpu 1:
 nilfs_segctor_thread+0x6ac/0x700 fs/nilfs2/segment.c:2611
 kthread+0x1fa/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff8880224d89e8 of 8 bytes by task 8467 on cpu 0:
 nilfs_segctor_kill_thread fs/nilfs2/segment.c:2641 [inline]
 nilfs_segctor_destroy fs/nilfs2/segment.c:2723 [inline]
 nilfs_detach_log_writer+0x16c/0x570 fs/nilfs2/segment.c:2812
 nilfs_put_super+0x2f/0xf0 fs/nilfs2/super.c:467
 generic_shutdown_super+0xcd/0x1f0 fs/super.c:464
 kill_block_super+0x4a/0x90 fs/super.c:1446
 deactivate_locked_super+0x6a/0xb0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1125
 task_work_run+0x8e/0x110 kernel/task_work.c:151
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
 exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8467 Comm: syz-executor.5 Not tainted 5.10.0-rc1-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	2020/10/27 13:55	upstream	4525c8781ec0	94942294	.config	log	report			info