lkml.org 
[lkml]   [2014]   [Feb]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 11/11] mempolicy: apply page table walker on queue_pages_range()
On 02/21/2014 11:58 AM, Naoya Horiguchi wrote:
> Hi Sasha,
>
> On Fri, Feb 21, 2014 at 01:30:53AM -0500, Sasha Levin wrote:
>> On 02/10/2014 04:44 PM, Naoya Horiguchi wrote:
>>> queue_pages_range() does page table walking in its own way now,
>>> so this patch rewrites it with walk_page_range().
>>> One difficulty was that queue_pages_range() needed to check vmas
>>> to determine whether we queue pages from a given vma or skip it.
>>> Now we have test_walk() callback in mm_walk for that purpose,
>>> so we can do the replacement cleanly. queue_pages_test_walk()
>>> depends on not only the current vma but also the previous one,
>>> so we use queue_pages->prev to keep it.
>>>
>>> ChangeLog v2:
>>> - rebase onto mmots
>>> - add VM_PFNMAP check on queue_pages_test_walk()
>>>
>>> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>>> ---
>>
>> Hi Naoya,
>>
>> I'm seeing another spew in today's -next, and it seems to be related
>> to this patch. Here's the spew (with line numbers instead of kernel
>> addresses):
>
> Thanks. (line numbers translation is very helpful.)
>
> This bug looks strange to me.
> "kernel BUG at mm/hugetlb.c:3580" means we try to do isolate_huge_page()
> for !PageHead page. But the caller queue_pages_hugetlb() gets the page
> with "page = pte_page(huge_ptep_get(pte))", so it should be the head page!
>
> mm/hugetlb.c:3580 is VM_BUG_ON_PAGE(!PageHead(page), page), so we expect to
> have dump_page output at this point, is that in your kernel log?

This is usually a sign of a race between that code and thp splitting, see
https://lkml.org/lkml/2013/12/23/457 for example.

I forgot to add the dump_page output to my extraction process and the complete logs all long gone.
I'll grab it when it happens again.


Thanks,
Sasha


\
 
 \ /
  Last update: 2014-02-21 19:01    [W:0.237 / U:1.252 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site