[syzbot] WARNING: suspicious RCU usage in remove_vma (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1e43c377 Merge tag 'xtensa-20210329' of git://github.com/j..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1052e1d6d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=d1a3d65a48dbd1bc
dashboard link: https://syzkaller.appspot.com/bug?extid=26ad5e106ca477175819

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+26ad5e...@syzkaller.appspotmail.com

=============================
WARNING: suspicious RCU usage
5.12.0-rc5-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:8294 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
no locks held by syz-executor.0/29105.

stack backtrace:
CPU: 0 PID: 29105 Comm: syz-executor.0 Not tainted 5.12.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
___might_sleep+0x229/0x2c0 kernel/sched/core.c:8294
remove_vma+0x44/0x170 mm/mmap.c:178
exit_mmap+0x33f/0x590 mm/mmap.c:3229
__mmput+0x122/0x470 kernel/fork.c:1090
mmput+0x58/0x60 kernel/fork.c:1111
exit_mm kernel/exit.c:501 [inline]
do_exit+0xb0a/0x2a60 kernel/exit.c:812
do_group_exit+0x125/0x310 kernel/exit.c:922
get_signal+0x47f/0x2150 kernel/signal.c:2781
arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:789
handle_signal_work kernel/entry/common.c:147 [inline]
exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
exit_to_user_mode_prepare+0x148/0x250 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: Unable to access opcode bytes at RIP 0x46642f.
RSP: 002b:00007fdfaa117218 EFLAGS: 00000246
ORIG_RAX: 00000000000000ca
RAX: 0000000000000000 RBX: 000000000056bf68 RCX: 0000000000466459
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000056bf68
RBP: 000000000056bf60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf6c
R13: 00007fff64c569cf R14: 00007fdfaa117300 R15: 0000000000022000


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[Matthew Wilcox]

#syz dup: WARNING: suspicious RCU usage in getname_flags