From: Sasha Levin <sasha.levin@oracle.com>
To: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>, Mel Gorman <mgorman@suse.de>,
Dave Jones <davej@redhat.com>, linux-mm <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Josh Boyer <jwboyer@fedoraproject.org>
Subject: Re: mm: BUG in do_huge_pmd_wp_page
Date: Thu, 15 May 2014 13:43:28 -0400 [thread overview]
Message-ID: <5374FCC0.8010809@oracle.com> (raw)
In-Reply-To: <alpine.LSU.2.11.1405151034160.4721@eggly.anvils>
On 05/15/2014 01:37 PM, Hugh Dickins wrote:
> On Thu, 15 May 2014, Sasha Levin wrote:
>> On 04/07/2014 04:11 PM, Kirill A. Shutemov wrote:
>>> On Mon, Apr 07, 2014 at 03:40:46PM -0400, Sasha Levin wrote:
>>>>> It also breaks fairly quickly under testing because:
>>>>>
>>>>> On 04/07/2014 10:48 AM, Kirill A. Shutemov wrote:
>>>>>>> + if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
>>>>>>> + spin_lock(ptl);
>>>>>
>>>>> ^ We go into atomic
>>>>>
>>>>>>> + if (unlikely(!pmd_same(*pmd, orig_pmd)))
>>>>>>> + goto out_race;
>>>>>>> + }
>>>>>>> +
>>>>>>> if (!page)
>>>>>>> clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
>>>>>>> else
>>>>>>> copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
>>>>>
>>>>> copy_user_huge_page() doesn't like running in atomic state,
>>>>> and asserts might_sleep().
>>> Okay, I'll try something else.
>>
>> I've Cc'ed Josh Boyer to this since it just occurred to me that Fedora
>> is running with CONFIG_DEBUG_VM set, where this bug is rather easy to
>> trigger.
>>
>> This issue was neglected because it triggers only on CONFIG_DEBUG_VM builds,
>> but with Fedora running that, maybe it shouldn't be?
>
> But it triggers only on CONFIG_DEBUG_PAGEALLOC builds, doesn't it?
> I hope Fedora doesn't go out with that enabled.
Ow, it needs DEBUG_PAGEALLOC too? I forgot about that one.
No problem for Fedora then, sorry for the noise :(
Thanks,
Sasha
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next prev parent reply other threads:[~2014-05-15 17:46 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-29 13:04 mm: BUG in do_huge_pmd_wp_page Sasha Levin
2013-04-04 14:03 ` Sasha Levin
2013-04-04 14:30 ` Kirill A. Shutemov
2013-04-04 14:37 ` Sasha Levin
2013-04-04 16:28 ` Kirill A. Shutemov
2013-04-04 21:54 ` Sasha Levin
2014-04-04 19:37 ` Sasha Levin
2014-04-07 14:48 ` Kirill A. Shutemov
2014-04-07 14:56 ` Sasha Levin
2014-04-07 19:40 ` Sasha Levin
2014-04-07 20:11 ` Kirill A. Shutemov
2014-05-15 17:31 ` Sasha Levin
2014-05-15 17:37 ` Hugh Dickins
2014-05-15 17:43 ` Sasha Levin [this message]
2014-05-15 17:58 ` Hugh Dickins
2013-04-10 8:02 ` Minchan Kim
2013-04-11 13:18 ` Kirill A. Shutemov
2013-04-14 7:13 ` Minchan Kim
2013-04-11 14:55 ` Sasha Levin
2013-04-11 15:13 ` Kirill A. Shutemov
2013-04-11 15:14 ` Sasha Levin
2013-04-24 22:46 ` Andrew Morton
2013-04-26 0:51 ` Sasha Levin
2013-04-26 2:01 ` Dave Jones
2013-04-26 3:12 ` Sasha Levin
2014-02-04 3:01 ` Sasha Levin
2014-02-04 3:59 ` Hugh Dickins
2014-02-04 16:58 ` Kirill A. Shutemov
2014-02-05 18:12 ` Sasha Levin
2014-02-05 22:50 ` Hugh Dickins
2013-04-24 22:51 ` H. Peter Anvin
2013-04-24 23:40 ` Simon Jeons
2013-04-26 2:28 ` H. Peter Anvin
2013-04-26 1:30 ` Minchan Kim
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