WARNING: suspicious RCU usage in inode

WARNING: suspicious RCU usage in inode_security
Status: upstream: reported on 2021/01/20 03:59
Reported-by: syzbot+37978b81dea56c7a4249@syzkaller.appspotmail.com
First crash: 43d, last: 43d

Sample crash report:

=============================
WARNING: suspicious RCU usage
5.11.0-rc3-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:7867 Illegal context switch in RCU-bh read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
1 lock held by kworker/u17:3/10446:
 #0: ffff888014f94c00 (&sig->cred_guard_mutex){+.+.}-{3:3}, at: prepare_bprm_creds fs/exec.c:1462 [inline]
 #0: ffff888014f94c00 (&sig->cred_guard_mutex){+.+.}-{3:3}, at: bprm_execve+0xb2/0x19a0 fs/exec.c:1794

stack backtrace:
CPU: 1 PID: 10446 Comm: kworker/u17:3 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 ___might_sleep+0x229/0x2c0 kernel/sched/core.c:7867
 __inode_security_revalidate security/selinux/hooks.c:259 [inline]
 inode_security+0x5d/0x130 security/selinux/hooks.c:296
 selinux_file_permission+0x140/0x520 security/selinux/hooks.c:3549
 security_file_permission+0x56/0x560 security/security.c:1448
 rw_verify_area+0x115/0x350 fs/read_write.c:400
 kernel_read+0x2a/0x70 fs/read_write.c:469
 prepare_binprm fs/exec.c:1646 [inline]
 search_binary_handler fs/exec.c:1700 [inline]
 exec_binprm fs/exec.c:1757 [inline]
 bprm_execve fs/exec.c:1826 [inline]
 bprm_execve+0x740/0x19a0 fs/exec.c:1788
 kernel_execve+0x370/0x460 fs/exec.c:1969
 call_usermodehelper_exec_async+0x2de/0x580 kernel/umh.c:110
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-qemu-upstream	2021/01/16 03:51	upstream	82821be8	65a7a854	.config	log	report			info