* [PATCH] mm: hwpoison: Use compound_head() flags for huge pages
@ 2017-05-24 13:02 James Morse
2017-05-24 15:57 ` Punit Agrawal
2017-05-24 23:30 ` Naoya Horiguchi
0 siblings, 2 replies; 3+ messages in thread
From: James Morse @ 2017-05-24 13:02 UTC (permalink / raw)
To: linux-mm; +Cc: Naoya Horiguchi, James Morse, Punit Agrawal
memory_failure() chooses a recovery action function based on the page
flags. For huge pages it uses the tail page flags which don't have
anything interesting set, resulting in:
> Memory failure: 0x9be3b4: Unknown page state
> Memory failure: 0x9be3b4: recovery action for unknown page: Failed
Instead, save a copy of the head page's flags if this is a huge page,
this means if there are no relevant flags for this tail page, we use
the head pages flags instead. This results in the me_huge_page()
recovery action being called:
> Memory failure: 0x9b7969: recovery action for huge page: Delayed
For hugepages that have not yet been allocated, this allows the hugepage
to be dequeued.
CC: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
This is intended as a fix, but I can't find the patch that introduced this
behaviour. (not recent, and there is a lot of history down there!)
This doesn't apply to stable trees before v3.10...
Cc: stable@vger.kernel.org # 3.10.105
mm/memory-failure.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 2527dfeddb00..44a6a33af219 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1184,7 +1184,10 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
* page_remove_rmap() in try_to_unmap_one(). So to determine page status
* correctly, we save a copy of the page flags at this time.
*/
- page_flags = p->flags;
+ if (PageHuge(p))
+ page_flags = hpage->flags;
+ else
+ page_flags = p->flags;
/*
* unpoison always clear PG_hwpoison inside page lock
--
2.11.0
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: hwpoison: Use compound_head() flags for huge pages
2017-05-24 13:02 [PATCH] mm: hwpoison: Use compound_head() flags for huge pages James Morse
@ 2017-05-24 15:57 ` Punit Agrawal
2017-05-24 23:30 ` Naoya Horiguchi
1 sibling, 0 replies; 3+ messages in thread
From: Punit Agrawal @ 2017-05-24 15:57 UTC (permalink / raw)
To: James Morse; +Cc: linux-mm, Naoya Horiguchi
James Morse <james.morse@arm.com> writes:
> memory_failure() chooses a recovery action function based on the page
> flags. For huge pages it uses the tail page flags which don't have
> anything interesting set, resulting in:
>> Memory failure: 0x9be3b4: Unknown page state
>> Memory failure: 0x9be3b4: recovery action for unknown page: Failed
>
> Instead, save a copy of the head page's flags if this is a huge page,
> this means if there are no relevant flags for this tail page, we use
> the head pages flags instead. This results in the me_huge_page()
> recovery action being called:
>> Memory failure: 0x9b7969: recovery action for huge page: Delayed
>
> For hugepages that have not yet been allocated, this allows the hugepage
> to be dequeued.
>
> CC: Punit Agrawal <punit.agrawal@arm.com>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
> This is intended as a fix, but I can't find the patch that introduced this
> behaviour. (not recent, and there is a lot of history down there!)
>
> This doesn't apply to stable trees before v3.10...
> Cc: stable@vger.kernel.org # 3.10.105
>
> mm/memory-failure.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 2527dfeddb00..44a6a33af219 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1184,7 +1184,10 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
> * page_remove_rmap() in try_to_unmap_one(). So to determine page status
> * correctly, we save a copy of the page flags at this time.
> */
> - page_flags = p->flags;
> + if (PageHuge(p))
> + page_flags = hpage->flags;
> + else
> + page_flags = p->flags;
>
> /*
> * unpoison always clear PG_hwpoison inside page lock
I can confirm that this patch reduces the number of failing cases when
running hugepage tests from mce-tests suite.
FWIW,
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Tested-by: Punit Agrawal <punit.agrawal@arm.com>
Thanks!
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: hwpoison: Use compound_head() flags for huge pages
2017-05-24 13:02 [PATCH] mm: hwpoison: Use compound_head() flags for huge pages James Morse
2017-05-24 15:57 ` Punit Agrawal
@ 2017-05-24 23:30 ` Naoya Horiguchi
1 sibling, 0 replies; 3+ messages in thread
From: Naoya Horiguchi @ 2017-05-24 23:30 UTC (permalink / raw)
To: James Morse; +Cc: linux-mm, Punit Agrawal
On Wed, May 24, 2017 at 02:02:04PM +0100, James Morse wrote:
> memory_failure() chooses a recovery action function based on the page
> flags. For huge pages it uses the tail page flags which don't have
> anything interesting set, resulting in:
> > Memory failure: 0x9be3b4: Unknown page state
> > Memory failure: 0x9be3b4: recovery action for unknown page: Failed
>
> Instead, save a copy of the head page's flags if this is a huge page,
> this means if there are no relevant flags for this tail page, we use
> the head pages flags instead. This results in the me_huge_page()
> recovery action being called:
> > Memory failure: 0x9b7969: recovery action for huge page: Delayed
>
> For hugepages that have not yet been allocated, this allows the hugepage
> to be dequeued.
>
> CC: Punit Agrawal <punit.agrawal@arm.com>
> Signed-off-by: James Morse <james.morse@arm.com>
Looks good to me.
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> ---
> This is intended as a fix, but I can't find the patch that introduced this
> behaviour. (not recent, and there is a lot of history down there!)
Please add a tag
Fixes: 524fca1e7356 ("HWPOISON: fix misjudgement of page_action() for errors on mlocked pages")
>
> This doesn't apply to stable trees before v3.10...
> Cc: stable@vger.kernel.org # 3.10.105
You can skip older stable kernels to which the fix isn't cleanly applicable.
Thanks,
Naoya Horiguchi
>
> mm/memory-failure.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 2527dfeddb00..44a6a33af219 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1184,7 +1184,10 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
> * page_remove_rmap() in try_to_unmap_one(). So to determine page status
> * correctly, we save a copy of the page flags at this time.
> */
> - page_flags = p->flags;
> + if (PageHuge(p))
> + page_flags = hpage->flags;
> + else
> + page_flags = p->flags;
>
> /*
> * unpoison always clear PG_hwpoison inside page lock
> --
> 2.11.0
>
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2017-05-24 13:02 [PATCH] mm: hwpoison: Use compound_head() flags for huge pages James Morse
2017-05-24 15:57 ` Punit Agrawal
2017-05-24 23:30 ` Naoya Horiguchi
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