KCSAN: data-race in p9_client_cb / p9_client

KCSAN: data-race in p9_client_cb / p9_client_rpc (3)
Status: auto-closed as invalid on 2021/04/24 11:05
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 250d, last: 218d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in p9_client_cb / p9_client_rpc (4)	5	149d	161d	0/22	auto-closed as invalid on 2021/07/02 20:41
upstream	KCSAN: data-race in p9_client_cb / p9_client_rpc (5)	1	113d	113d	0/22	auto-closed as invalid on 2021/08/07 12:54
upstream	KCSAN: data-race in p9_client_cb / p9_client_rpc (2)	1	468d	468d	0/22	auto-closed as invalid on 2020/08/17 23:12
upstream	KCSAN: data-race in p9_client_cb / p9_client_rpc	2	712d	713d	0/22	auto-closed as invalid on 2020/01/21 10:36

Sample crash report:

==================================================================
BUG: KCSAN: data-race in p9_client_cb / p9_client_rpc

write to 0xffff88810e971000 of 4 bytes by task 3793 on cpu 0:
 p9_client_cb+0x14/0x40 net/9p/client.c:429
 p9_conn_cancel+0x3a1/0x400 net/9p/trans_fd.c:215
 p9_poll_mux net/9p/trans_fd.c:628 [inline]
 p9_poll_workfn+0x14c/0x410 net/9p/trans_fd.c:1145
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88810e971000 of 4 bytes by task 31854 on cpu 1:
 p9_client_rpc+0x26f/0x660 net/9p/client.c:759
 p9_client_version+0x8e/0x340 net/9p/client.c:945
 p9_client_create+0x601/0x6f0 net/9p/client.c:1055
 v9fs_session_init+0xf5/0xd90 fs/9p/v9fs.c:406
 v9fs_mount+0x57/0x550 fs/9p/vfs_super.c:126
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:592
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1497
 do_new_mount fs/namespace.c:2903 [inline]
 path_mount+0x11b9/0x1c00 fs/namespace.c:3233
 do_mount fs/namespace.c:3246 [inline]
 __do_sys_mount fs/namespace.c:3454 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3431
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3431
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 31854 Comm: syz-executor.5 Not tainted 5.12.0-rc3-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	2021/03/20 11:04	upstream	1c273e10bc0c	e45f5621	.config	log	report			info	KCSAN: data-race in p9_client_cb / p9_client_rpc
ci2-upstream-kcsan-gce	2021/02/16 21:38	upstream	f40ddce88593	98682e5e	.config	log	report			info	KCSAN: data-race in p9_client_cb / p9_client_rpc