linux-kernel - [syzbot] WARNING: lock held when returning to user space in alloc

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Message-ID: <0000000000006dd10705e99314a8@google.com>
Date:   Mon, 26 Sep 2022 04:46:35 -0700
From:   syzbot <syzbot+7379d1edb09dff51e4a6@...kaller.appspotmail.com>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: [syzbot] WARNING: lock held when returning to user space in alloc_super

Hello,

syzbot found the following issue on:

HEAD commit:    f76349cf4145 Linux 6.0-rc7
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=122d6188880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ba0d23aa7e1ffaf5
dashboard link: https://syzkaller.appspot.com/bug?extid=7379d1edb09dff51e4a6
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2

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+7379d1edb09dff51e4a6@...kaller.appspotmail.com

================================================
WARNING: lock held when returning to user space!
6.0.0-rc7-syzkaller #0 Not tainted
------------------------------------------------
syz-executor.2/11590 is leaving the kernel with locks still held!
2 locks held by syz-executor.2/11590:
 #0: ffff888073cb60e0 (&type->s_umount_key#64/1){+.+.}-{3:3}, at: alloc_super+0x212/0x920 fs/super.c:228
 #1: ffff88802d1df8f0 (&sb->s_type->i_lock_key#40){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline]
 #1: ffff88802d1df8f0 (&sb->s_type->i_lock_key#40){+.+.}-{2:2}, at: _atomic_dec_and_lock+0x9d/0x110 lib/dec_and_lock.c:28
BUG: scheduling while atomic: syz-executor.2/11590/0x00000002
INFO: lockdep is turned off.
Modules linked in:
Preemption disabled at:
[<0000000000000000>] 0x0
Kernel panic - not syncing: scheduling while atomic
CPU: 1 PID: 11590 Comm: syz-executor.2 Not tainted 6.0.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
 panic+0x2d6/0x715 kernel/panic.c:274
 __schedule_bug+0x1ff/0x250 kernel/sched/core.c:5724
 schedule_debug+0x1d3/0x3c0 kernel/sched/core.c:5753
 __schedule+0xfb/0xdf0 kernel/sched/core.c:6388
 schedule+0xcb/0x190 kernel/sched/core.c:6570
 exit_to_user_mode_loop+0xe5/0x150 kernel/entry/common.c:157
 exit_to_user_mode_prepare+0xb2/0x140 kernel/entry/common.c:201
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:307
 exc_general_protection+0x298/0x430 arch/x86/kernel/traps.c:719
 asm_exc_general_protection+0x22/0x30 arch/x86/include/asm/idtentry.h:564
 </TASK>
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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