linux-kernel - Re: [syzbot] BUG: sleeping function called from invalid context in __purge_vmap_area

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Date:   Fri, 17 Jun 2022 17:17:05 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     syzbot <syzbot+0bce0ec817c084f98c56@...kaller.appspotmail.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        syzkaller-bugs@...glegroups.com,
        "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [syzbot] BUG: sleeping function called from invalid context in
 __purge_vmap_area_lazy

On Thu, 16 Jun 2022 23:08:21 -0700 syzbot <syzbot+0bce0ec817c084f98c56@...kaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    6012273897fe Add linux-next specific files for 20220615
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=16d2f608080000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=b4154677977b1776
> dashboard link: https://syzkaller.appspot.com/bug?extid=0bce0ec817c084f98c56
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> 
> Unfortunately, I don't have any reproducer for this issue yet.

I don't get this.  __purge_vmap_area_lazy() seems to be doing
everything right wrt its use of free_vmap_area_lock and the
cond_resched_lock().

It's a shame that the "Preemption disabled at:" thing isn't working. 
Peter, Thomas: any ideas why this would happen?

Thanks.


> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+0bce0ec817c084f98c56@...kaller.appspotmail.com
> 
> BUG: sleeping function called from invalid context at mm/vmalloc.c:1759
> BUG: sleeping function called from invalid context at mm/vmalloc.c:1759
> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1795, name: kworker/1:2
> preempt_count: 2, expected: 1
> RCU nest depth: 0, expected: 0
> 4 locks held by kworker/1:2/1795:
>  #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
>  #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
>  #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:636 [inline]
>  #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:663 [inline]
>  #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x87a/0x1610 kernel/workqueue.c:2260
>  #1: ffffc90006c07da8 (drain_vmap_work){+.+.}-{0:0}, at: process_one_work+0x8ae/0x1610 kernel/workqueue.c:2264
>  #2: ffffffff8bebb028 (vmap_purge_lock){+.+.}-{3:3}, at: drain_vmap_area_work+0x44/0xe0 mm/vmalloc.c:1781
>  #3: ffffffff8bebb2f8 (free_vmap_area_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:360 [inline]
>  #3: ffffffff8bebb2f8 (free_vmap_area_lock){+.+.}-{2:2}, at: __cond_resched_lock+0xa6/0xe0 kernel/sched/core.c:8306
> Preemption disabled at:
> [<0000000000000000>] 0x0
> CPU: 1 PID: 1795 Comm: kworker/1:2 Not tainted 5.19.0-rc2-next-20220615-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: events drain_vmap_area_work
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
>  __might_resched.cold+0x222/0x26b kernel/sched/core.c:9823
>  __purge_vmap_area_lazy+0x95c/0x1c50 mm/vmalloc.c:1759
>  drain_vmap_area_work+0x52/0xe0 mm/vmalloc.c:1782
>  process_one_work+0x996/0x1610 kernel/workqueue.c:2289
>  worker_thread+0x665/0x1080 kernel/workqueue.c:2436
>  kthread+0x2e9/0x3a0 kernel/kthread.c:376
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
>  </TASK>
> BUG: workqueue leaked lock or atomic: kworker/1:2/0x00000001/1795
>      last function: drain_vmap_area_work
> no locks held by kworker/1:2/1795.
> CPU: 1 PID: 1795 Comm: kworker/1:2 Tainted: G        W         5.19.0-rc2-next-20220615-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: events drain_vmap_area_work
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
>  process_one_work.cold+0x96/0xb8 kernel/workqueue.c:2304
>  worker_thread+0x665/0x1080 kernel/workqueue.c:2436
>  kthread+0x2e9/0x3a0 kernel/kthread.c:376
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
>  </TASK>
> BUG: scheduling while atomic: kworker/1:2/1795/0x00000002
> no locks held by kworker/1:2/1795.
> Modules linked in:
> Preemption disabled at:
> [<0000000000000000>] 0x0
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
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> 
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