From: Michel Lespinasse <walken@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Sasha Levin <sasha.levin@oracle.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
Hugh Dickins <hughd@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] mm: use long type for page counts in mm_populate() and get_user_pages()
Date: Thu, 7 Feb 2013 13:35:20 -0800 [thread overview]
Message-ID: <CANN689FV+0Z_TuqWKdsmUHk7HMFDuk31uQO=eH79+249nfOQrQ@mail.gmail.com> (raw)
In-Reply-To: <20130206171047.d27b5772.akpm@linux-foundation.org>
On Wed, Feb 6, 2013 at 5:10 PM, Andrew Morton <akpm@linux-foundation.org> wrote:
> On Wed, 06 Feb 2013 19:39:11 -0500
> Sasha Levin <sasha.levin@oracle.com> wrote:
>
>> We're now hitting the VM_BUG_ON() which was added in the last hunk of the
>> patch:
>
> hm, why was that added.
>
> Michel, I seem to have confused myself over this series. I saw a
> report this morning which led me to drop
> mm-accelerate-munlock-treatment-of-thp-pages.patch but now I can't find
> that report and I'm wondering if I should have dropped
> mm-accelerate-mm_populate-treatment-of-thp-pages.patch instead.
>
> Given that and Sasha's new report I think I'll drop
>
> mm-use-long-type-for-page-counts-in-mm_populate-and-get_user_pages.patch
> mm-use-long-type-for-page-counts-in-mm_populate-and-get_user_pages-fix.patch
> mm-use-long-type-for-page-counts-in-mm_populate-and-get_user_pages-fix-fix.patch
> mm-accelerate-mm_populate-treatment-of-thp-pages.patch
> mm-accelerate-munlock-treatment-of-thp-pages.patch
>
> and let's start again?
All right. My bad, there were issues in the patch series. I think
there were two:
- The VM_BUG_ON(!reg) in "mm: use long type for page counts in
mm_populate() and get_user_pages()". The intention there was to test
for what happened in the original overflow case, which is that gup
would return 0 as the passed nr_pages argument (when passed as an int)
would be <= 0. As it turns out, this didn't account for the other case
where gup returns 0, which is when the first page is file-backed, not
found in page cache, and the mmap_sem gets dropped due to a non-NULL
"nonblocking" argument (as is the case with mm_populate())
- The issue in munlock, where the page mask wasn't correctly computed
due to an off by 1 issue.
I agree a clean resend seems the most appropriate course of action at
this point. Sorry for the trouble :/
--
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
--
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next prev parent reply other threads:[~2013-02-07 21:35 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-31 0:26 [PATCH 0/3] fixes for large mm_populate() and munlock() operations Michel Lespinasse
2013-01-31 0:26 ` [PATCH 1/3] mm: use long type for page counts in mm_populate() and get_user_pages() Michel Lespinasse
2013-01-31 0:42 ` Andrew Morton
2013-02-07 0:39 ` Sasha Levin
2013-02-07 1:10 ` Andrew Morton
2013-02-07 1:16 ` Sasha Levin
2013-02-07 21:35 ` Michel Lespinasse [this message]
2013-01-31 0:26 ` [PATCH 2/3] mm: accelerate mm_populate() treatment of THP pages Michel Lespinasse
2013-01-31 3:05 ` Hugh Dickins
2013-01-31 4:27 ` Michel Lespinasse
2013-02-02 0:08 ` Andrew Morton
2013-01-31 0:26 ` [RFC PATCH 3/3] mm: accelerate munlock() " Michel Lespinasse
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