linux-kernel - WARNING: suspicious RCU usage in remove

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Message-ID: <000000000000a4ef2405b563a244@google.com>
Date:   Tue, 01 Dec 2020 01:20:18 -0800
From:   syzbot <syzbot+a6beff5dda6d8ea00582@...kaller.appspotmail.com>
To:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, syzkaller-bugs@...glegroups.com
Subject: WARNING: suspicious RCU usage in remove_vma

Hello,

syzbot found the following issue on:

HEAD commit:    99c710c4 Merge tag 'platform-drivers-x86-v5.10-2' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15638bf1500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6d1e98d0b97781e4
dashboard link: https://syzkaller.appspot.com/bug?extid=a6beff5dda6d8ea00582
compiler:       gcc (GCC) 10.1.0-syz 20200507

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+a6beff5dda6d8ea00582@...kaller.appspotmail.com

=============================
WARNING: suspicious RCU usage
5.10.0-rc5-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:7270 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 blkid/11233.

stack backtrace:
CPU: 1 PID: 11233 Comm: blkid Not tainted 5.10.0-rc5-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:77 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:118
 ___might_sleep+0x220/0x2b0 kernel/sched/core.c:7270
 remove_vma+0x44/0x170 mm/mmap.c:178
 exit_mmap+0x351/0x530 mm/mmap.c:3233
 __mmput+0x122/0x470 kernel/fork.c:1079
 mmput+0x53/0x60 kernel/fork.c:1100
 exit_mm kernel/exit.c:486 [inline]
 do_exit+0xa72/0x29b0 kernel/exit.c:796
 do_group_exit+0x125/0x310 kernel/exit.c:906
 __do_sys_exit_group kernel/exit.c:917 [inline]
 __se_sys_exit_group kernel/exit.c:915 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:915
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f2b794631e8
Code: Unable to access opcode bytes at RIP 0x7f2b794631be.
RSP: 002b:00007ffcfbbb2458 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f2b794631e8
RDX: 0000000000000002 RSI: 000000000000003c RDI: 0000000000000002
RBP: 00007f2b79738840 R08: 00000000000000e7 R09: ffffffffffffffa8
R10: 00007f2b7973e740 R11: 0000000000000246 R12: 00007f2b79738840
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000


---
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