[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 6 Jun 2017 16:02:10 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Andrew Morton <akpm@...ux-foundation.org>,
Larry Finger <Larry.Finger@...inger.net>
Cc: LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: Sleeping BUG in khugepaged for i586
On 06/05/2017 11:44 PM, Andrew Morton wrote:
> On Sat, 3 Jun 2017 14:24:26 -0500 Larry Finger <Larry.Finger@...inger.net> wrote:
>
>> I recently turned on locking diagnostics for a Dell Latitude D600 laptop, which
>> requires a 32-bit kernel. In the log I found the following:
>>
>> BUG: sleeping function called from invalid context at mm/khugepaged.c:655
>> in_atomic(): 1, irqs_disabled(): 0, pid: 20, name: khugepaged
>> 1 lock held by khugepaged/20:
>> #0: (&mm->mmap_sem){++++++}, at: [<c03d6609>]
>> collapse_huge_page.isra.47+0x439/0x1240
>> CPU: 0 PID: 20 Comm: khugepaged Tainted: G W
W means thre was WARN earler. Could be related... Got logs?
>> 4.12.0-rc1-wl-12125-g952a068 #80
What is "wl-12125-g952a068"? What patches on top of mainline?
>> Hardware name: Dell Computer Corporation Latitude D600
>> /03U652, BIOS A05 05/29/2003
>> Call Trace:
>> dump_stack+0x76/0xb2
>> ___might_sleep+0x174/0x230
>> collapse_huge_page.isra.47+0xacf/0x1240
>> khugepaged_scan_mm_slot+0x41e/0xc00
>> ? _raw_spin_lock+0x46/0x50
>> khugepaged+0x277/0x4f0
>> ? prepare_to_wait_event+0xe0/0xe0
>> kthread+0xeb/0x120
>> ? khugepaged_scan_mm_slot+0xc00/0xc00
>> ? kthread_create_on_node+0x30/0x30
>> ret_from_fork+0x21/0x30
>>
>> I have no idea when this problem was introduced. Of course, I will test any
>> proposed fixes.
>>
>
> Odd. There's nothing wrong with cond_resched() while holding mmap_sem.
> It looks like khugepaged forgot to do a spin_unlock somewhere and we
> leaked a preempt_count.
Hmm I'd expect such spin lock to be reported together with mmap_sem in
the debugging "locks held" message?
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@...ck.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
>
Powered by blists - more mailing lists