From: Larry Woodman <lwoodman@redhat.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>, Hugh Dickins <hughd@google.com>,
Michal Hocko <mhocko@suse.cz>, Linux-MM <linux-mm@kvack.org>,
David Gibson <david@gibson.dropbear.id.au>,
Ken Chen <kenchen@google.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -alternative] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables V2 (resend)
Date: Fri, 27 Jul 2012 06:10:55 -0400 [thread overview]
Message-ID: <5012692F.5080501@redhat.com> (raw)
In-Reply-To: <50120FA8.20409@redhat.com>
On 07/26/2012 11:48 PM, Larry Woodman wrote:
Mel, did you see this???
Larry
>> This patch looks good to me.
>>
>> Larry, does Hugh's patch survive your testing?
>>
>>
>
> Like I said earlier, no. However, I finally set up a reproducer that
> only takes a few seconds
> on a large system and this totally fixes the problem:
>
> -------------------------------------------------------------------------------------------------------------------------
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index c36febb..cc023b8 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2151,7 +2151,7 @@ int copy_hugetlb_page_range(struct mm_struct
> *dst, struct mm_struct *src,
> goto nomem;
>
> /* If the pagetables are shared don't copy or take
> references */
> - if (dst_pte == src_pte)
> + if (*(unsigned long *)dst_pte == *(unsigned long
> *)src_pte)
> continue;
>
> spin_lock(&dst->page_table_lock);
> ---------------------------------------------------------------------------------------------------------------------------
>
>
> When we compare what the src_pte & dst_pte point to instead of their
> addresses everything works,
> I suspect there is a missing memory barrier somewhere ???
>
> Larry
>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: Larry Woodman <lwoodman@redhat.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>, Hugh Dickins <hughd@google.com>,
Michal Hocko <mhocko@suse.cz>, Linux-MM <linux-mm@kvack.org>,
David Gibson <david@gibson.dropbear.id.au>,
Ken Chen <kenchen@google.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -alternative] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables V2 (resend)
Date: Fri, 27 Jul 2012 06:10:55 -0400 [thread overview]
Message-ID: <5012692F.5080501@redhat.com> (raw)
In-Reply-To: <50120FA8.20409@redhat.com>
On 07/26/2012 11:48 PM, Larry Woodman wrote:
Mel, did you see this???
Larry
>> This patch looks good to me.
>>
>> Larry, does Hugh's patch survive your testing?
>>
>>
>
> Like I said earlier, no. However, I finally set up a reproducer that
> only takes a few seconds
> on a large system and this totally fixes the problem:
>
> -------------------------------------------------------------------------------------------------------------------------
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index c36febb..cc023b8 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2151,7 +2151,7 @@ int copy_hugetlb_page_range(struct mm_struct
> *dst, struct mm_struct *src,
> goto nomem;
>
> /* If the pagetables are shared don't copy or take
> references */
> - if (dst_pte == src_pte)
> + if (*(unsigned long *)dst_pte == *(unsigned long
> *)src_pte)
> continue;
>
> spin_lock(&dst->page_table_lock);
> ---------------------------------------------------------------------------------------------------------------------------
>
>
> When we compare what the src_pte & dst_pte point to instead of their
> addresses everything works,
> I suspect there is a missing memory barrier somewhere ???
>
> Larry
>
next prev parent reply other threads:[~2012-07-27 10:11 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-20 13:49 [PATCH] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables v2 Mel Gorman
2012-07-20 13:49 ` Mel Gorman
2012-07-20 14:11 ` [PATCH] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables V2 (resend) Mel Gorman
2012-07-20 14:11 ` Mel Gorman
2012-07-20 14:29 ` Michal Hocko
2012-07-20 14:29 ` Michal Hocko
2012-07-20 14:37 ` Mel Gorman
2012-07-20 14:37 ` Mel Gorman
2012-07-20 14:40 ` Michal Hocko
2012-07-20 14:40 ` Michal Hocko
2012-07-20 14:36 ` [PATCH -alternative] " Michal Hocko
2012-07-20 14:36 ` Michal Hocko
2012-07-20 14:51 ` Mel Gorman
2012-07-20 14:51 ` Mel Gorman
2012-07-23 4:04 ` Hugh Dickins
2012-07-23 4:04 ` Hugh Dickins
2012-07-23 11:40 ` Mel Gorman
2012-07-23 11:40 ` Mel Gorman
2012-07-24 1:08 ` Hugh Dickins
2012-07-24 1:08 ` Hugh Dickins
2012-07-24 8:32 ` Michal Hocko
2012-07-24 8:32 ` Michal Hocko
2012-07-24 9:34 ` Mel Gorman
2012-07-24 9:34 ` Mel Gorman
2012-07-24 10:04 ` Michal Hocko
2012-07-24 10:04 ` Michal Hocko
2012-07-24 19:23 ` Hugh Dickins
2012-07-24 19:23 ` Hugh Dickins
2012-07-25 8:36 ` Mel Gorman
2012-07-25 8:36 ` Mel Gorman
2012-07-26 17:42 ` Rik van Riel
2012-07-26 17:42 ` Rik van Riel
2012-07-26 18:04 ` Larry Woodman
2012-07-26 18:04 ` Larry Woodman
2012-07-27 8:42 ` Mel Gorman
2012-07-27 8:42 ` Mel Gorman
2012-07-26 18:37 ` Rik van Riel
2012-07-26 18:37 ` Rik van Riel
2012-07-26 21:03 ` Larry Woodman
2012-07-26 21:03 ` Larry Woodman
2012-07-27 3:48 ` Larry Woodman
2012-07-27 3:48 ` Larry Woodman
2012-07-27 10:10 ` Larry Woodman [this message]
2012-07-27 10:10 ` Larry Woodman
2012-07-27 10:23 ` Mel Gorman
2012-07-27 10:23 ` Mel Gorman
2012-07-27 10:36 ` Larry Woodman
2012-07-27 10:36 ` Larry Woodman
2012-07-30 19:11 ` Larry Woodman
2012-07-30 19:11 ` Larry Woodman
2012-07-31 12:16 ` Hillf Danton
2012-07-31 12:16 ` Hillf Danton
2012-07-31 12:46 ` Mel Gorman
2012-07-31 12:46 ` Mel Gorman
2012-07-31 13:07 ` Larry Woodman
2012-07-31 13:07 ` Larry Woodman
2012-07-31 13:29 ` Mel Gorman
2012-07-31 13:29 ` Mel Gorman
2012-07-31 13:21 ` Michal Hocko
2012-07-31 13:21 ` Michal Hocko
2012-07-31 17:49 ` Larry Woodman
2012-07-31 17:49 ` Larry Woodman
2012-07-31 20:06 ` Michal Hocko
2012-07-31 20:06 ` Michal Hocko
2012-07-31 20:57 ` Larry Woodman
2012-07-31 20:57 ` Larry Woodman
2012-08-01 2:45 ` Larry Woodman
2012-08-01 2:45 ` Larry Woodman
2012-08-01 8:20 ` Michal Hocko
2012-08-01 8:20 ` Michal Hocko
2012-08-01 12:32 ` Michal Hocko
2012-08-01 12:32 ` Michal Hocko
2012-08-01 15:06 ` Larry Woodman
2012-08-01 15:06 ` Larry Woodman
2012-08-02 7:19 ` Michal Hocko
2012-08-02 7:19 ` Michal Hocko
2012-08-02 7:37 ` Mel Gorman
2012-08-02 7:37 ` Mel Gorman
2012-08-02 12:36 ` Michal Hocko
2012-08-02 12:36 ` Michal Hocko
2012-08-02 13:33 ` Mel Gorman
2012-08-02 13:33 ` Mel Gorman
2012-08-02 13:53 ` Michal Hocko
2012-08-02 13:53 ` Michal Hocko
2012-07-31 18:03 ` Rik van Riel
2012-07-31 18:03 ` Rik van Riel
2012-07-26 18:31 ` Rik van Riel
2012-07-26 18:31 ` Rik van Riel
2012-07-27 9:02 ` Michal Hocko
2012-07-27 9:02 ` Michal Hocko
2012-07-26 16:01 ` [PATCH] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables v2 Larry Woodman
2012-07-26 16:01 ` Larry Woodman
2012-07-27 8:47 ` Mel Gorman
2012-07-27 8:47 ` Mel Gorman
2012-07-26 21:00 ` Rik van Riel
2012-07-26 21:00 ` Rik van Riel
2012-07-26 21:54 ` Hugh Dickins
2012-07-26 21:54 ` Hugh Dickins
2012-07-27 8:52 ` Mel Gorman
2012-07-27 8:52 ` Mel Gorman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5012692F.5080501@redhat.com \
--to=lwoodman@redhat.com \
--cc=david@gibson.dropbear.id.au \
--cc=hughd@google.com \
--cc=kenchen@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=mhocko@suse.cz \
--cc=riel@redhat.com \
--cc=xiyou.wangcong@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.