* [PATCH] mm: softdirty: keep bit when zapping file pte
@ 2014-09-20 8:03 Peter Feiner
2014-09-20 8:08 ` Cyrill Gorcunov
2014-09-24 21:59 ` Andrew Morton
0 siblings, 2 replies; 5+ messages in thread
From: Peter Feiner @ 2014-09-20 8:03 UTC (permalink / raw)
To: linux-mm
Cc: linux-kernel, Cyrill Gorcunov, Pavel Emelyanov, Jamie Liu,
Hugh Dickins, Andrew Morton, Peter Feiner
Fixes the same bug as b43790eedd31e9535b89bbfa45793919e9504c34 and
9aed8614af5a05cdaa32a0b78b0f1a424754a958 where the return value of
pte_*mksoft_dirty was being ignored.
To be sure that no other pte/pmd "mk" function return values were
being ignored, I annotated the functions in
arch/x86/include/asm/pgtable.h with __must_check and rebuilt.
Signed-off-by: Peter Feiner <pfeiner@google.com>
---
mm/memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c
index adeac30..fc46934 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1125,7 +1125,7 @@ again:
addr) != page->index) {
pte_t ptfile = pgoff_to_pte(page->index);
if (pte_soft_dirty(ptent))
- pte_file_mksoft_dirty(ptfile);
+ ptfile = pte_file_mksoft_dirty(ptfile);
set_pte_at(mm, addr, pte, ptfile);
}
if (PageAnon(page))
--
2.1.0.rc2.206.gedb03e5
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^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] mm: softdirty: keep bit when zapping file pte
2014-09-20 8:03 [PATCH] mm: softdirty: keep bit when zapping file pte Peter Feiner
@ 2014-09-20 8:08 ` Cyrill Gorcunov
2014-09-24 21:59 ` Andrew Morton
1 sibling, 0 replies; 5+ messages in thread
From: Cyrill Gorcunov @ 2014-09-20 8:08 UTC (permalink / raw)
To: Peter Feiner
Cc: linux-mm, linux-kernel, Pavel Emelyanov, Jamie Liu, Hugh Dickins,
Andrew Morton
On Sat, Sep 20, 2014 at 01:03:07AM -0700, Peter Feiner wrote:
> Fixes the same bug as b43790eedd31e9535b89bbfa45793919e9504c34 and
> 9aed8614af5a05cdaa32a0b78b0f1a424754a958 where the return value of
> pte_*mksoft_dirty was being ignored.
>
> To be sure that no other pte/pmd "mk" function return values were
> being ignored, I annotated the functions in
> arch/x86/include/asm/pgtable.h with __must_check and rebuilt.
>
> Signed-off-by: Peter Feiner <pfeiner@google.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
I might be missing it, thanks a huge Peter!
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: softdirty: keep bit when zapping file pte
2014-09-20 8:03 [PATCH] mm: softdirty: keep bit when zapping file pte Peter Feiner
2014-09-20 8:08 ` Cyrill Gorcunov
@ 2014-09-24 21:59 ` Andrew Morton
2014-09-24 22:45 ` Peter Feiner
2014-09-25 6:30 ` Cyrill Gorcunov
1 sibling, 2 replies; 5+ messages in thread
From: Andrew Morton @ 2014-09-24 21:59 UTC (permalink / raw)
To: Peter Feiner
Cc: linux-mm, linux-kernel, Cyrill Gorcunov, Pavel Emelyanov,
Jamie Liu, Hugh Dickins
On Sat, 20 Sep 2014 01:03:07 -0700 Peter Feiner <pfeiner@google.com> wrote:
> Fixes the same bug as b43790eedd31e9535b89bbfa45793919e9504c34 and
> 9aed8614af5a05cdaa32a0b78b0f1a424754a958 where the return value of
> pte_*mksoft_dirty was being ignored.
>
> To be sure that no other pte/pmd "mk" function return values were
> being ignored, I annotated the functions in
> arch/x86/include/asm/pgtable.h with __must_check and rebuilt.
>
Grumble.
It is useful to identify preceding similar patches but that isn't a
good way of describing *this* patch. What is wrong with the current
code, how does the patch fix it.
And, particularly, what do you think are the end-user visible effects
of the bug? This info helps people to work out which kernel versions
need the fix.
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: softdirty: keep bit when zapping file pte
2014-09-24 21:59 ` Andrew Morton
@ 2014-09-24 22:45 ` Peter Feiner
2014-09-25 6:30 ` Cyrill Gorcunov
1 sibling, 0 replies; 5+ messages in thread
From: Peter Feiner @ 2014-09-24 22:45 UTC (permalink / raw)
To: Andrew Morton
Cc: Cyrill Gorcunov, Pavel Emelyanov, Jamie Liu, linux-mm,
Hugh Dickins, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 989 bytes --]
On Sep 24, 2014 2:59 PM, "Andrew Morton" <akpm@linux-foundation.org> wrote:
>
> On Sat, 20 Sep 2014 01:03:07 -0700 Peter Feiner <pfeiner@google.com>
wrote:
>
> > Fixes the same bug as b43790eedd31e9535b89bbfa45793919e9504c34 and
> > 9aed8614af5a05cdaa32a0b78b0f1a424754a958 where the return value of
> > pte_*mksoft_dirty was being ignored.
> >
> > To be sure that no other pte/pmd "mk" function return values were
> > being ignored, I annotated the functions in
> > arch/x86/include/asm/pgtable.h with __must_check and rebuilt.
> >
>
> Grumble.
>
> It is useful to identify preceding similar patches but that isn't a
> good way of describing *this* patch. What is wrong with the current
> code, how does the patch fix it.
>
> And, particularly, what do you think are the end-user visible effects
> of the bug? This info helps people to work out which kernel versions
> need the fix.
>
Let me think about this and cook up a test case. I'll submit a v2 with a
better description.
Peter
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: softdirty: keep bit when zapping file pte
2014-09-24 21:59 ` Andrew Morton
2014-09-24 22:45 ` Peter Feiner
@ 2014-09-25 6:30 ` Cyrill Gorcunov
1 sibling, 0 replies; 5+ messages in thread
From: Cyrill Gorcunov @ 2014-09-25 6:30 UTC (permalink / raw)
To: Andrew Morton
Cc: Peter Feiner, linux-mm, linux-kernel, Pavel Emelyanov, Jamie Liu,
Hugh Dickins
On Wed, Sep 24, 2014 at 02:59:27PM -0700, Andrew Morton wrote:
> On Sat, 20 Sep 2014 01:03:07 -0700 Peter Feiner <pfeiner@google.com> wrote:
>
> > Fixes the same bug as b43790eedd31e9535b89bbfa45793919e9504c34 and
> > 9aed8614af5a05cdaa32a0b78b0f1a424754a958 where the return value of
> > pte_*mksoft_dirty was being ignored.
> >
> > To be sure that no other pte/pmd "mk" function return values were
> > being ignored, I annotated the functions in
> > arch/x86/include/asm/pgtable.h with __must_check and rebuilt.
> >
>
> Grumble.
>
> It is useful to identify preceding similar patches but that isn't a
> good way of describing *this* patch. What is wrong with the current
> code, how does the patch fix it.
The userspace effect is that without this patch softdirty mark might be lost
if file mapped pte get zapped. It should go into @stable series after 3.12.
>
> And, particularly, what do you think are the end-user visible effects
> of the bug? This info helps people to work out which kernel versions
> need the fix.
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^ permalink raw reply [flat|nested] 5+ messages in thread
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2014-09-20 8:03 [PATCH] mm: softdirty: keep bit when zapping file pte Peter Feiner
2014-09-20 8:08 ` Cyrill Gorcunov
2014-09-24 21:59 ` Andrew Morton
2014-09-24 22:45 ` Peter Feiner
2014-09-25 6:30 ` Cyrill Gorcunov
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