KCSAN: data-race in get_tree

KCSAN: data-race in get_tree_bdev / kmmpd

Status: auto-obsoleted due to no activity on 2022/11/18 13:30
Subsystems: ext4
[Documentation on labels]
First crash: 1034d, last: 1034d

▶ ▼ Similar bugs (1)

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in get_tree_bdev / kmmpd (2) ext4	6				1	755d	755d	0/29	auto-obsoleted due to no activity on 2023/08/24 14:10

Sample crash report:

==================================================================
BUG: KCSAN: data-race in get_tree_bdev / kmmpd

read-write to 0xffff888138ef7850 of 8 bytes by task 3302 on cpu 1:
 get_tree_bdev+0x32b/0x3b0 fs/super.c:1329
 ext4_get_tree+0x18/0x20 fs/ext4/super.c:5678
 vfs_get_tree+0x49/0x190 fs/super.c:1530
 do_new_mount+0x200/0x650 fs/namespace.c:3040
 path_mount+0x4aa/0xb70 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount+0x281/0x2d0 fs/namespace.c:3568
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888138ef7850 of 8 bytes by task 3303 on cpu 0:
 sb_rdonly include/linux/fs.h:2301 [inline]
 kmmpd+0x19d/0x660 fs/ext4/mmp.c:157
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

value changed: 0x0000000010810000 -> 0x0000000070810000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3303 Comm: kmmpd-loop1 Not tainted 6.0.0-syzkaller-11849-g6d84c258e804-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
==================================================================

Crashes (1):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Assets (help?)	Manager	Title
2022/10/14 13:22	upstream	6d84c258e804	4954e4b2	.config	console log	report			info		ci2-upstream-kcsan-gce	KCSAN: data-race in get_tree_bdev / kmmpd

* ~~Struck through~~ repros no longer work on HEAD.