* [PATCH] mm: hugetlb: fix pgoff computation when unmapping page from vma
@ 2011-12-20 13:45 Hillf Danton
2011-12-20 14:14 ` Michal Hocko
2011-12-21 2:46 ` KAMEZAWA Hiroyuki
0 siblings, 2 replies; 3+ messages in thread
From: Hillf Danton @ 2011-12-20 13:45 UTC (permalink / raw)
To: Michal Hocko; +Cc: KAMEZAWA Hiroyuki, Andrew Morton, linux-mm, LKML
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.
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>
---
--- 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);
mapping = (struct address_space *)page_private(page);
/*
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: hugetlb: fix pgoff computation when unmapping page from vma
2011-12-20 13:45 [PATCH] mm: hugetlb: fix pgoff computation when unmapping page from vma Hillf Danton
@ 2011-12-20 14:14 ` Michal Hocko
2011-12-21 2:46 ` KAMEZAWA Hiroyuki
1 sibling, 0 replies; 3+ messages in thread
From: Michal Hocko @ 2011-12-20 14:14 UTC (permalink / raw)
To: Hillf Danton; +Cc: KAMEZAWA Hiroyuki, Andrew Morton, linux-mm, LKML, Mel Gorman
[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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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: hugetlb: fix pgoff computation when unmapping page from vma
2011-12-20 13:45 [PATCH] mm: hugetlb: fix pgoff computation when unmapping page from vma Hillf Danton
2011-12-20 14:14 ` Michal Hocko
@ 2011-12-21 2:46 ` KAMEZAWA Hiroyuki
1 sibling, 0 replies; 3+ messages in thread
From: KAMEZAWA Hiroyuki @ 2011-12-21 2:46 UTC (permalink / raw)
To: Hillf Danton; +Cc: Michal Hocko, Andrew Morton, linux-mm, LKML
On Tue, 20 Dec 2011 21:45:51 +0800
Hillf Danton <dhillf@gmail.com> 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.
>
> 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: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-12-20 13:45 [PATCH] mm: hugetlb: fix pgoff computation when unmapping page from vma Hillf Danton
2011-12-20 14:14 ` Michal Hocko
2011-12-21 2:46 ` KAMEZAWA Hiroyuki
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