From: Minchan Kim <minchan@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Mel Gorman <mgorman@suse.de>,
Andrea Arcangeli <aarcange@redhat.com>,
Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v2] thp: use is_zero_pfn only after pte_present check
Date: Tue, 13 Oct 2015 18:10:53 +0900 [thread overview]
Message-ID: <20151013091053.GA6630@bbox> (raw)
In-Reply-To: <561CB297.9080600@suse.cz>
On Tue, Oct 13, 2015 at 09:28:23AM +0200, Vlastimil Babka wrote:
> On 10/13/2015 04:38 AM, Minchan Kim wrote:
> >Use is_zero_pfn on pteval only after pte_present check on pteval
> >(It might be better idea to introduce is_zero_pte where checks
> >pte_present first). Otherwise, it could work with swap or
> >migration entry and if pte_pfn's result is equal to zero_pfn
> >by chance, we lose user's data in __collapse_huge_page_copy.
> >So if you're luck, the application is segfaulted and finally you
> >could see below message when the application is exit.
> >
> >BUG: Bad rss-counter state mm:ffff88007f099300 idx:2 val:3
> >
> >Cc: <stable@vger.kernel.org>
>
> More specific:
> Cc: <stable@vger.kernel.org> # 4.1+
> Fixes: ca0984caa823 ("mm: incorporate zero pages into transparent
> huge pages")
>
> >Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
Thanks for the detail and review, Vlastimil.
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prev parent reply other threads:[~2015-10-13 9:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-13 2:38 Minchan Kim
2015-10-13 5:41 ` Greg Kroah-Hartman
2015-10-13 6:26 ` Minchan Kim
2015-10-13 7:28 ` Vlastimil Babka
2015-10-13 9:10 ` Minchan Kim [this message]
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