WARNING: suspicious RCU usage in __inode_security

WARNING: suspicious RCU usage in __inode_security_revalidate
Status: upstream: reported on 2021/02/28 21:38
Reported-by: syzbot+1058632e58766789d9f2@syzkaller.appspotmail.com
First crash: 57d, last: 57d

Sample crash report:

=============================
WARNING: suspicious RCU usage
5.11.0-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:8296 Illegal context switch in RCU-sched read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
2 locks held by syz-executor.0/10588:
 #0: ffff88801ec94460 (sb_writers#5){.+.+}-{0:0}, at: do_unlinkat+0x190/0x690 fs/namei.c:4075
 #1: ffff888024cc2548 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:810 [inline]
 #1: ffff888024cc2548 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at: do_unlinkat+0x27d/0x690 fs/namei.c:4079

stack backtrace:
CPU: 1 PID: 10588 Comm: syz-executor.0 Not tainted 5.11.0-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0xfa/0x151 lib/dump_stack.c:120
 ___might_sleep+0x266/0x2c0 kernel/sched/core.c:8296
 __inode_security_revalidate+0x112/0x140 security/selinux/hooks.c:259
 inode_security_rcu security/selinux/hooks.c:285 [inline]
 selinux_inode_permission+0x2e1/0x670 security/selinux/hooks.c:3137
 security_inode_permission+0x92/0xf0 security/security.c:1268
 inode_permission.part.0+0x119/0x440 fs/namei.c:521
 inode_permission fs/namei.c:2812 [inline]
 may_delete+0x318/0x750 fs/namei.c:2790
 vfs_unlink+0x53/0x610 fs/namei.c:4012
 do_unlinkat+0x3de/0x690 fs/namei.c:4096
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x465837
Code: 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdb29f6728 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000465837
RDX: 00007ffdb29f6760 RSI: 00007ffdb29f6760 RDI: 00007ffdb29f67f0
RBP: 00007ffdb29f67f0 R08: 0000000000000001 R09: 00007ffdb29f65c0
R10: 000000000253588b R11: 0000000000000206 R12: 00000000004bbe42
R13: 00007ffdb29f78c0 R14: 0000000002535810 R15: 00007ffdb29f7900

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-qemu-upstream	2021/02/24 21:34	upstream	719bbd4a	fcc6d71b	.config	log	report			info	WARNING: suspicious RCU usage in __inode_security_revalidate