From: Michal Hocko <mhocko@suse.cz>
To: Hillf Danton <dhillf@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@suse.de>
Subject: Re: [PATCH] mm: hugetlb: fix pgoff computation when unmapping page from vma
Date: Tue, 20 Dec 2011 15:14:37 +0100 [thread overview]
Message-ID: <20111220141437.GJ10565@tiehlicka.suse.cz> (raw)
In-Reply-To: <CAJd=RBDC9hxAFbbTvSWVa=t1kuyBH8=UoTYxRDtDm6iXLGkQWg@mail.gmail.com>
[CCing Mel]
On Tue 20-12-11 21:45:51, Hillf Danton wrote:
> The computation for pgoff is incorrect, at least with
>
> (vma->vm_pgoff >> PAGE_SHIFT)
>
> involved. It is fixed with the available method if HPAGE_SIZE is concerned in
> page cache lookup.
Have you seen this as a real issue? I guess nobody noticed as it is
quite rare error case.
Anyways, yes, looks good.
> Cc: Michal Hocko <mhocko@suse.cz>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Hillf Danton <dhillf@gmail.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
> ---
>
> --- a/mm/hugetlb.c Tue Dec 20 21:26:30 2011
> +++ b/mm/hugetlb.c Tue Dec 20 21:40:44 2011
> @@ -2315,8 +2315,7 @@ static int unmap_ref_private(struct mm_s
> * from page cache lookup which is in HPAGE_SIZE units.
> */
> address = address & huge_page_mask(h);
> - pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
> - + (vma->vm_pgoff >> PAGE_SHIFT);
> + pgoff = linear_hugepage_index(vma, address);
You have hstate so you can use vma_hugecache_offset directly
> mapping = (struct address_space *)page_private(page);
>
> /*
>
Thanks
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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next prev parent reply other threads:[~2011-12-20 14:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-20 13:45 Hillf Danton
2011-12-20 14:14 ` Michal Hocko [this message]
2011-12-21 2:46 ` KAMEZAWA Hiroyuki
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