KCSAN: data-race in d_set_mounted / dput (3)

KCSAN: data-race in d_set_mounted / dput (3)
Status: auto-closed as invalid on 2020/09/06 07:28
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 393d, last: 360d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in d_set_mounted / dput (4)	3	262d	233d	0/22	auto-closed as invalid on 2020/12/21 11:47
upstream	KCSAN: data-race in d_set_mounted / dput	2	612d	625d	0/22	auto-closed as invalid on 2020/02/02 04:47
upstream	KCSAN: data-race in d_set_mounted / dput (5)	8	104d	193d	0/22	auto-closed as invalid on 2021/05/20 02:25
upstream	KCSAN: data-race in d_set_mounted / dput (2)	2	421d	425d	0/22	closed as invalid on 2020/06/18 14:13

Sample crash report:

==================================================================
BUG: KCSAN: data-race in d_set_mounted / dput

write to 0xffff88811cdafe40 of 4 bytes by task 12231 on cpu 0:
 d_set_mounted+0xfc/0x190 fs/dcache.c:1459
 get_mountpoint+0x1be/0x300 fs/namespace.c:740
 lock_mount+0x86/0x1d0 fs/namespace.c:2200
 do_loopback fs/namespace.c:2349 [inline]
 do_mount+0xc5f/0x1c00 fs/namespace.c:3194
 __do_sys_mount fs/namespace.c:3410 [inline]
 __se_sys_mount+0xd3/0x100 fs/namespace.c:3387
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3387
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811cdafe40 of 4 bytes by task 12225 on cpu 1:
 fast_dput fs/dcache.c:746 [inline]
 dput+0x2f/0x420 fs/dcache.c:865
 __fput+0x32c/0x460 fs/file_table.c:294
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:135
 get_signal+0x3f6/0x1650 kernel/signal.c:2547
 do_signal+0x25/0x270 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop arch/x86/entry/common.c:235 [inline]
 __prepare_exit_to_usermode+0x127/0x230 arch/x86/entry/common.c:269
 __syscall_return_slowpath+0x47/0x60 arch/x86/entry/common.c:352
 do_syscall_64+0x5d/0xb0 arch/x86/entry/common.c:393
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12225 Comm: syz-executor.4 Not tainted 5.8.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (4):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report
ci2-upstream-kcsan-gce	2020/08/02 07:20	upstream	ac3a0c847296	96dd3623	.config	log	report
ci2-upstream-kcsan-gce	2020/08/01 06:34	upstream	7dc6fd0f3b84	8df85ed9	.config	log	report
ci2-upstream-kcsan-gce	2020/07/22 14:59	upstream	4fa640dc5230	128cd85f	.config	log	report
ci2-upstream-kcsan-gce	2020/06/30 11:09	upstream	7c30b859a947	917afeaa	.config	log	report