* [PATCH] mm: Actually clear pmd_numa before invalidating
@ 2014-08-13 15:28 Matthew Wilcox
2014-08-13 15:56 ` Rik van Riel
` (2 more replies)
0 siblings, 3 replies; 9+ messages in thread
From: Matthew Wilcox @ 2014-08-13 15:28 UTC (permalink / raw)
To: linux-mm; +Cc: Matthew Wilcox, Mel Gorman, Rik van Riel, stable, Andrew Morton
Commit 67f87463d3 cleared the NUMA bit in a copy of the PMD entry, but
then wrote back the original
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
mm/pgtable-generic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index a8b9199..dfb79e0 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -195,7 +195,7 @@ void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
pmd_t entry = *pmdp;
if (pmd_numa(entry))
entry = pmd_mknonnuma(entry);
- set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(*pmdp));
+ set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(entry));
flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
--
2.0.0
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^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH] mm: Actually clear pmd_numa before invalidating
2014-08-13 15:28 [PATCH] mm: Actually clear pmd_numa before invalidating Matthew Wilcox
@ 2014-08-13 15:56 ` Rik van Riel
2014-08-13 16:32 ` Mel Gorman
2014-08-13 19:59 ` Andrew Morton
2 siblings, 0 replies; 9+ messages in thread
From: Rik van Riel @ 2014-08-13 15:56 UTC (permalink / raw)
To: Matthew Wilcox, linux-mm; +Cc: Mel Gorman, stable, Andrew Morton
On 08/13/2014 11:28 AM, Matthew Wilcox wrote:
> Commit 67f87463d3 cleared the NUMA bit in a copy of the PMD entry, but
> then wrote back the original
>
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: <stable@vger.kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] mm: Actually clear pmd_numa before invalidating
2014-08-13 15:28 [PATCH] mm: Actually clear pmd_numa before invalidating Matthew Wilcox
2014-08-13 15:56 ` Rik van Riel
@ 2014-08-13 16:32 ` Mel Gorman
2014-08-13 19:59 ` Andrew Morton
2 siblings, 0 replies; 9+ messages in thread
From: Mel Gorman @ 2014-08-13 16:32 UTC (permalink / raw)
To: Matthew Wilcox; +Cc: linux-mm, Rik van Riel, stable, Andrew Morton
On Wed, Aug 13, 2014 at 11:28:27AM -0400, Matthew Wilcox wrote:
> Commit 67f87463d3 cleared the NUMA bit in a copy of the PMD entry, but
> then wrote back the original
>
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: <stable@vger.kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mel Gorman <mgorman@suse.de>
--
Mel Gorman
SUSE Labs
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] mm: Actually clear pmd_numa before invalidating
2014-08-13 15:28 [PATCH] mm: Actually clear pmd_numa before invalidating Matthew Wilcox
2014-08-13 15:56 ` Rik van Riel
2014-08-13 16:32 ` Mel Gorman
@ 2014-08-13 19:59 ` Andrew Morton
2014-08-13 20:04 ` Wilcox, Matthew R
2 siblings, 1 reply; 9+ messages in thread
From: Andrew Morton @ 2014-08-13 19:59 UTC (permalink / raw)
To: Matthew Wilcox; +Cc: linux-mm, Mel Gorman, Rik van Riel, stable
On Wed, 13 Aug 2014 11:28:27 -0400 Matthew Wilcox <matthew.r.wilcox@intel.com> wrote:
> Commit 67f87463d3 cleared the NUMA bit in a copy of the PMD entry, but
> then wrote back the original
>
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: <stable@vger.kernel.org>
What are the runtime effects of this patch?
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^ permalink raw reply [flat|nested] 9+ messages in thread
* RE: [PATCH] mm: Actually clear pmd_numa before invalidating
2014-08-13 19:59 ` Andrew Morton
@ 2014-08-13 20:04 ` Wilcox, Matthew R
2014-08-13 20:12 ` Andrew Morton
0 siblings, 1 reply; 9+ messages in thread
From: Wilcox, Matthew R @ 2014-08-13 20:04 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-mm, Mel Gorman, Rik van Riel, stable
The commit log for 67f87463d3 explains what the runtime effects should have been. This simply fixes a typo in that patch that caused that patch to be a no-op.
-----Original Message-----
From: Andrew Morton [mailto:akpm@linux-foundation.org]
Sent: Wednesday, August 13, 2014 1:00 PM
To: Wilcox, Matthew R
Cc: linux-mm@kvack.org; Mel Gorman; Rik van Riel; stable@vger.kernel.org
Subject: Re: [PATCH] mm: Actually clear pmd_numa before invalidating
On Wed, 13 Aug 2014 11:28:27 -0400 Matthew Wilcox <matthew.r.wilcox@intel.com> wrote:
> Commit 67f87463d3 cleared the NUMA bit in a copy of the PMD entry, but
> then wrote back the original
>
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: <stable@vger.kernel.org>
What are the runtime effects of this patch?
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] mm: Actually clear pmd_numa before invalidating
2014-08-13 20:04 ` Wilcox, Matthew R
@ 2014-08-13 20:12 ` Andrew Morton
2014-08-13 20:16 ` Wilcox, Matthew R
0 siblings, 1 reply; 9+ messages in thread
From: Andrew Morton @ 2014-08-13 20:12 UTC (permalink / raw)
To: Wilcox, Matthew R; +Cc: linux-mm, Mel Gorman, Rik van Riel, stable
On Wed, 13 Aug 2014 20:04:02 +0000 "Wilcox, Matthew R" <matthew.r.wilcox@intel.com> wrote:
> The commit log for 67f87463d3 explains what the runtime effects should have been.
No it doesn't. In fact the sentence "The existing caller of
pmdp_invalidate should handle it but it's an inconsistent state for a
PMD." makes me suspect there are no end-user visible effects.
I don't know why we chose to backport that one into -stable and I don't
know why we should backport this one either.
Greg (and others) will look at this changelog and wonder "why". It
should tell them.
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* RE: [PATCH] mm: Actually clear pmd_numa before invalidating
2014-08-13 20:12 ` Andrew Morton
@ 2014-08-13 20:16 ` Wilcox, Matthew R
2014-08-13 20:23 ` Andrew Morton
0 siblings, 1 reply; 9+ messages in thread
From: Wilcox, Matthew R @ 2014-08-13 20:16 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-mm, Mel Gorman, Rik van Riel, stable
I am quite shockingly ignorant of the MM code. While looking at this function to figure out how/whether to use it, I noticed the bug, and sent a patch. I assumed the gibberish in the changelog meant something important to people who actually understand this part of the kernel :-)
-----Original Message-----
From: Andrew Morton [mailto:akpm@linux-foundation.org]
Sent: Wednesday, August 13, 2014 1:13 PM
To: Wilcox, Matthew R
Cc: linux-mm@kvack.org; Mel Gorman; Rik van Riel; stable@vger.kernel.org
Subject: Re: [PATCH] mm: Actually clear pmd_numa before invalidating
On Wed, 13 Aug 2014 20:04:02 +0000 "Wilcox, Matthew R" <matthew.r.wilcox@intel.com> wrote:
> The commit log for 67f87463d3 explains what the runtime effects should have been.
No it doesn't. In fact the sentence "The existing caller of
pmdp_invalidate should handle it but it's an inconsistent state for a
PMD." makes me suspect there are no end-user visible effects.
I don't know why we chose to backport that one into -stable and I don't
know why we should backport this one either.
Greg (and others) will look at this changelog and wonder "why". It
should tell them.
--
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] mm: Actually clear pmd_numa before invalidating
2014-08-13 20:16 ` Wilcox, Matthew R
@ 2014-08-13 20:23 ` Andrew Morton
2014-08-13 21:18 ` Mel Gorman
0 siblings, 1 reply; 9+ messages in thread
From: Andrew Morton @ 2014-08-13 20:23 UTC (permalink / raw)
To: Wilcox, Matthew R; +Cc: linux-mm, Mel Gorman, Rik van Riel, stable
On Wed, 13 Aug 2014 20:16:31 +0000 "Wilcox, Matthew R" <matthew.r.wilcox@intel.com> wrote:
> I am quite shockingly ignorant of the MM code. While looking at this
> function to figure out how/whether to use it, I noticed the bug, and
> sent a patch. I assumed the gibberish in the changelog meant something
> important to people who actually understand this part of the kernel :-)
Fair enough ;) Mel?
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] mm: Actually clear pmd_numa before invalidating
2014-08-13 20:23 ` Andrew Morton
@ 2014-08-13 21:18 ` Mel Gorman
0 siblings, 0 replies; 9+ messages in thread
From: Mel Gorman @ 2014-08-13 21:18 UTC (permalink / raw)
To: Andrew Morton; +Cc: Wilcox, Matthew R, linux-mm, Rik van Riel, stable
On Wed, Aug 13, 2014 at 01:23:33PM -0700, Andrew Morton wrote:
> On Wed, 13 Aug 2014 20:16:31 +0000 "Wilcox, Matthew R" <matthew.r.wilcox@intel.com> wrote:
>
> > I am quite shockingly ignorant of the MM code. While looking at this
> > function to figure out how/whether to use it, I noticed the bug, and
> > sent a patch. I assumed the gibberish in the changelog meant something
> > important to people who actually understand this part of the kernel :-)
>
> Fair enough ;) Mel?
The issue was theoritical in nature. The patch was meant to guarantee
the PTE was in a known state. As I cannot think of a way it could
trigger a bug I wouldn't consider it -stable material but Matthew's
patch is still doing the expected thing.
--
Mel Gorman
SUSE Labs
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^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2014-08-13 21:18 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
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2014-08-13 15:28 [PATCH] mm: Actually clear pmd_numa before invalidating Matthew Wilcox
2014-08-13 15:56 ` Rik van Riel
2014-08-13 16:32 ` Mel Gorman
2014-08-13 19:59 ` Andrew Morton
2014-08-13 20:04 ` Wilcox, Matthew R
2014-08-13 20:12 ` Andrew Morton
2014-08-13 20:16 ` Wilcox, Matthew R
2014-08-13 20:23 ` Andrew Morton
2014-08-13 21:18 ` Mel Gorman
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