Re: + mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch added to -mm tree
On 10/24/2014 05:00 AM, Joonsoo Kim wrote:
On Thu, Oct 23, 2014 at 10:39:45AM +0200, Vlastimil Babka wrote:
On 10/23/2014 10:15 AM, Joonsoo Kim wrote:
On Tue, Oct 14, 2014 at 01:53:44PM -0700, a...@linux-foundation.org wrote:
The patch titled
Subject: mm/compaction.c: avoid premature range skip in
isolate_migratepages_range
has been added to the -mm tree. Its filename is
mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
--
From: Joonsoo Kim
Subject: mm/compaction.c: avoid premature range skip in
isolate_migratepages_range
commit edc2ca612496 ("mm, compaction: move pageblock checks up from
isolate_migratepages_range()") commonizes isolate_migratepages variants
and make them use isolate_migratepages_block().
isolate_migratepages_block() could stop the execution when enough pages
are isolated, but, there is no code in isolate_migratepages_range() to
handle this case. In the result, even if isolate_migratepages_block()
returns prematurely without checking all pages in the range,
isolate_migratepages_block() is called repeately on the following
pageblock and some pages in the previous range are skipped to check.
Then, CMA is failed frequently due to this fact.
To fix this problem, this patch let isolate_migratepages_range() know the
situation that enough pages are isolated and stop the isolation in that
case.
Note that isolate_migratepages() has no such problem, because, it always
stops the isolation after just one call of isolate_migratepages_block().
Signed-off-by: Joonsoo Kim
Cc: Vlastimil Babka
Cc: David Rientjes
Cc: Minchan Kim
Cc: Michal Nazarewicz
Cc: Naoya Horiguchi
Cc: Christoph Lameter
Cc: Rik van Riel
Cc: Mel Gorman
Cc: Zhang Yanfei
Signed-off-by: Andrew Morton
Acked-by: Vlastimil Babka
Sorry for the trouble. But I think a more robust and future-proof fix
would be a check such as: if (pfn < block_end_pfn) break;
This should catch any reason where isolate_migratepages_block() did not
finish whole pageblock, and which was not fatal enough to return pfn==0.
However currently this seems to happen only due to isolating too much,
so your patch should work.
So it's up to you if you want to make the check more generic now, or
later after this bug is fixed for 3.18.
'if (pfn < block_end_pfn) break;' has one problem.
If we have enough isolated pages and reach at block_end_pfn,
we can't stop with above check.
Oh, right.
More proper check may be as following.
'if (pfn < block_end_pfn ||
cc->nr_migratepages == COMPACT_CLUSTER_MAX) break;'
But, as you mentioned, there is no case where 'pfn < block_end_pfn'
now, so I'd like to remain the patch as is.
Yep, that would only make things uglier :/ So I'm for merging your patch
in 3.18 cycle to prevent breakage.
Thanks.
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Re: + mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch added to -mm tree
On 10/24/2014 05:00 AM, Joonsoo Kim wrote: On Thu, Oct 23, 2014 at 10:39:45AM +0200, Vlastimil Babka wrote: On 10/23/2014 10:15 AM, Joonsoo Kim wrote: On Tue, Oct 14, 2014 at 01:53:44PM -0700, a...@linux-foundation.org wrote: The patch titled Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range has been added to the -mm tree. Its filename is mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch Before you just go and hit reply, please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days -- From: Joonsoo Kim iamjoonsoo@lge.com Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range commit edc2ca612496 (mm, compaction: move pageblock checks up from isolate_migratepages_range()) commonizes isolate_migratepages variants and make them use isolate_migratepages_block(). isolate_migratepages_block() could stop the execution when enough pages are isolated, but, there is no code in isolate_migratepages_range() to handle this case. In the result, even if isolate_migratepages_block() returns prematurely without checking all pages in the range, isolate_migratepages_block() is called repeately on the following pageblock and some pages in the previous range are skipped to check. Then, CMA is failed frequently due to this fact. To fix this problem, this patch let isolate_migratepages_range() know the situation that enough pages are isolated and stop the isolation in that case. Note that isolate_migratepages() has no such problem, because, it always stops the isolation after just one call of isolate_migratepages_block(). Signed-off-by: Joonsoo Kim iamjoonsoo@lge.com Cc: Vlastimil Babka vba...@suse.cz Cc: David Rientjes rient...@google.com Cc: Minchan Kim minc...@kernel.org Cc: Michal Nazarewicz min...@mina86.com Cc: Naoya Horiguchi n-horigu...@ah.jp.nec.com Cc: Christoph Lameter c...@linux.com Cc: Rik van Riel r...@redhat.com Cc: Mel Gorman mgor...@suse.de Cc: Zhang Yanfei zhangyan...@cn.fujitsu.com Signed-off-by: Andrew Morton a...@linux-foundation.org Acked-by: Vlastimil Babka vba...@suse.cz Sorry for the trouble. But I think a more robust and future-proof fix would be a check such as: if (pfn block_end_pfn) break; This should catch any reason where isolate_migratepages_block() did not finish whole pageblock, and which was not fatal enough to return pfn==0. However currently this seems to happen only due to isolating too much, so your patch should work. So it's up to you if you want to make the check more generic now, or later after this bug is fixed for 3.18. 'if (pfn block_end_pfn) break;' has one problem. If we have enough isolated pages and reach at block_end_pfn, we can't stop with above check. Oh, right. More proper check may be as following. 'if (pfn block_end_pfn || cc-nr_migratepages == COMPACT_CLUSTER_MAX) break;' But, as you mentioned, there is no case where 'pfn block_end_pfn' now, so I'd like to remain the patch as is. Yep, that would only make things uglier :/ So I'm for merging your patch in 3.18 cycle to prevent breakage. Thanks. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: + mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch added to -mm tree
On Thu, Oct 23, 2014 at 10:39:45AM +0200, Vlastimil Babka wrote:
> On 10/23/2014 10:15 AM, Joonsoo Kim wrote:
> > On Tue, Oct 14, 2014 at 01:53:44PM -0700, a...@linux-foundation.org wrote:
> >>
> >> The patch titled
> >> Subject: mm/compaction.c: avoid premature range skip in
> >> isolate_migratepages_range
> >> has been added to the -mm tree. Its filename is
> >>
> >> mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
> >>
> >> This patch should soon appear at
> >>
> >> http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
> >> and later at
> >>
> >> http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
> >>
> >> Before you just go and hit "reply", please:
> >>a) Consider who else should be cc'ed
> >>b) Prefer to cc a suitable mailing list as well
> >>c) Ideally: find the original patch on the mailing list and do a
> >> reply-to-all to that, adding suitable additional cc's
> >>
> >> *** Remember to use Documentation/SubmitChecklist when testing your code
> >> ***
> >>
> >> The -mm tree is included into linux-next and is updated
> >> there every 3-4 working days
> >>
> >> --
> >> From: Joonsoo Kim
> >> Subject: mm/compaction.c: avoid premature range skip in
> >> isolate_migratepages_range
> >>
> >> commit edc2ca612496 ("mm, compaction: move pageblock checks up from
> >> isolate_migratepages_range()") commonizes isolate_migratepages variants
> >> and make them use isolate_migratepages_block().
> >>
> >> isolate_migratepages_block() could stop the execution when enough pages
> >> are isolated, but, there is no code in isolate_migratepages_range() to
> >> handle this case. In the result, even if isolate_migratepages_block()
> >> returns prematurely without checking all pages in the range,
> >>
> >> isolate_migratepages_block() is called repeately on the following
> >> pageblock and some pages in the previous range are skipped to check.
> >> Then, CMA is failed frequently due to this fact.
> >>
> >> To fix this problem, this patch let isolate_migratepages_range() know the
> >> situation that enough pages are isolated and stop the isolation in that
> >> case.
> >>
> >> Note that isolate_migratepages() has no such problem, because, it always
> >> stops the isolation after just one call of isolate_migratepages_block().
> >>
> >> Signed-off-by: Joonsoo Kim
> >> Cc: Vlastimil Babka
> >> Cc: David Rientjes
> >> Cc: Minchan Kim
> >> Cc: Michal Nazarewicz
> >> Cc: Naoya Horiguchi
> >> Cc: Christoph Lameter
> >> Cc: Rik van Riel
> >> Cc: Mel Gorman
> >> Cc: Zhang Yanfei
> >> Signed-off-by: Andrew Morton
>
> Acked-by: Vlastimil Babka
>
> Sorry for the trouble. But I think a more robust and future-proof fix
> would be a check such as: if (pfn < block_end_pfn) break;
> This should catch any reason where isolate_migratepages_block() did not
> finish whole pageblock, and which was not fatal enough to return pfn==0.
> However currently this seems to happen only due to isolating too much,
> so your patch should work.
> So it's up to you if you want to make the check more generic now, or
> later after this bug is fixed for 3.18.
'if (pfn < block_end_pfn) break;' has one problem.
If we have enough isolated pages and reach at block_end_pfn,
we can't stop with above check.
More proper check may be as following.
'if (pfn < block_end_pfn ||
cc->nr_migratepages == COMPACT_CLUSTER_MAX) break;'
But, as you mentioned, there is no case where 'pfn < block_end_pfn'
now, so I'd like to remain the patch as is.
Thanks.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
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Please read the FAQ at http://www.tux.org/lkml/
Re: + mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch added to -mm tree
On 10/23/2014 10:15 AM, Joonsoo Kim wrote:
> On Tue, Oct 14, 2014 at 01:53:44PM -0700, a...@linux-foundation.org wrote:
>>
>> The patch titled
>> Subject: mm/compaction.c: avoid premature range skip in
>> isolate_migratepages_range
>> has been added to the -mm tree. Its filename is
>>
>> mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
>>
>> This patch should soon appear at
>>
>> http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
>> and later at
>>
>> http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
>>
>> Before you just go and hit "reply", please:
>>a) Consider who else should be cc'ed
>>b) Prefer to cc a suitable mailing list as well
>>c) Ideally: find the original patch on the mailing list and do a
>> reply-to-all to that, adding suitable additional cc's
>>
>> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>>
>> The -mm tree is included into linux-next and is updated
>> there every 3-4 working days
>>
>> --
>> From: Joonsoo Kim
>> Subject: mm/compaction.c: avoid premature range skip in
>> isolate_migratepages_range
>>
>> commit edc2ca612496 ("mm, compaction: move pageblock checks up from
>> isolate_migratepages_range()") commonizes isolate_migratepages variants
>> and make them use isolate_migratepages_block().
>>
>> isolate_migratepages_block() could stop the execution when enough pages
>> are isolated, but, there is no code in isolate_migratepages_range() to
>> handle this case. In the result, even if isolate_migratepages_block()
>> returns prematurely without checking all pages in the range,
>>
>> isolate_migratepages_block() is called repeately on the following
>> pageblock and some pages in the previous range are skipped to check.
>> Then, CMA is failed frequently due to this fact.
>>
>> To fix this problem, this patch let isolate_migratepages_range() know the
>> situation that enough pages are isolated and stop the isolation in that
>> case.
>>
>> Note that isolate_migratepages() has no such problem, because, it always
>> stops the isolation after just one call of isolate_migratepages_block().
>>
>> Signed-off-by: Joonsoo Kim
>> Cc: Vlastimil Babka
>> Cc: David Rientjes
>> Cc: Minchan Kim
>> Cc: Michal Nazarewicz
>> Cc: Naoya Horiguchi
>> Cc: Christoph Lameter
>> Cc: Rik van Riel
>> Cc: Mel Gorman
>> Cc: Zhang Yanfei
>> Signed-off-by: Andrew Morton
Acked-by: Vlastimil Babka
Sorry for the trouble. But I think a more robust and future-proof fix
would be a check such as: if (pfn < block_end_pfn) break;
This should catch any reason where isolate_migratepages_block() did not
finish whole pageblock, and which was not fatal enough to return pfn==0.
However currently this seems to happen only due to isolating too much,
so your patch should work.
So it's up to you if you want to make the check more generic now, or
later after this bug is fixed for 3.18.
Vlastimil
> Hello, Andrew.
>
> I forgot to mention that this should be merged for v3.18. :)
>
> Thanks.
>
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To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: + mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch added to -mm tree
On Tue, Oct 14, 2014 at 01:53:44PM -0700, a...@linux-foundation.org wrote:
>
> The patch titled
> Subject: mm/compaction.c: avoid premature range skip in
> isolate_migratepages_range
> has been added to the -mm tree. Its filename is
>
> mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
>
> This patch should soon appear at
>
> http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
> and later at
>
> http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
>
> Before you just go and hit "reply", please:
>a) Consider who else should be cc'ed
>b) Prefer to cc a suitable mailing list as well
>c) Ideally: find the original patch on the mailing list and do a
> reply-to-all to that, adding suitable additional cc's
>
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
>
> --
> From: Joonsoo Kim
> Subject: mm/compaction.c: avoid premature range skip in
> isolate_migratepages_range
>
> commit edc2ca612496 ("mm, compaction: move pageblock checks up from
> isolate_migratepages_range()") commonizes isolate_migratepages variants
> and make them use isolate_migratepages_block().
>
> isolate_migratepages_block() could stop the execution when enough pages
> are isolated, but, there is no code in isolate_migratepages_range() to
> handle this case. In the result, even if isolate_migratepages_block()
> returns prematurely without checking all pages in the range,
>
> isolate_migratepages_block() is called repeately on the following
> pageblock and some pages in the previous range are skipped to check.
> Then, CMA is failed frequently due to this fact.
>
> To fix this problem, this patch let isolate_migratepages_range() know the
> situation that enough pages are isolated and stop the isolation in that
> case.
>
> Note that isolate_migratepages() has no such problem, because, it always
> stops the isolation after just one call of isolate_migratepages_block().
>
> Signed-off-by: Joonsoo Kim
> Cc: Vlastimil Babka
> Cc: David Rientjes
> Cc: Minchan Kim
> Cc: Michal Nazarewicz
> Cc: Naoya Horiguchi
> Cc: Christoph Lameter
> Cc: Rik van Riel
> Cc: Mel Gorman
> Cc: Zhang Yanfei
> Signed-off-by: Andrew Morton
Hello, Andrew.
I forgot to mention that this should be merged for v3.18. :)
Thanks.
--
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Please read the FAQ at http://www.tux.org/lkml/
Re: + mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch added to -mm tree
On Tue, Oct 14, 2014 at 01:53:44PM -0700, a...@linux-foundation.org wrote: The patch titled Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range has been added to the -mm tree. Its filename is mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch Before you just go and hit reply, please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days -- From: Joonsoo Kim iamjoonsoo@lge.com Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range commit edc2ca612496 (mm, compaction: move pageblock checks up from isolate_migratepages_range()) commonizes isolate_migratepages variants and make them use isolate_migratepages_block(). isolate_migratepages_block() could stop the execution when enough pages are isolated, but, there is no code in isolate_migratepages_range() to handle this case. In the result, even if isolate_migratepages_block() returns prematurely without checking all pages in the range, isolate_migratepages_block() is called repeately on the following pageblock and some pages in the previous range are skipped to check. Then, CMA is failed frequently due to this fact. To fix this problem, this patch let isolate_migratepages_range() know the situation that enough pages are isolated and stop the isolation in that case. Note that isolate_migratepages() has no such problem, because, it always stops the isolation after just one call of isolate_migratepages_block(). Signed-off-by: Joonsoo Kim iamjoonsoo@lge.com Cc: Vlastimil Babka vba...@suse.cz Cc: David Rientjes rient...@google.com Cc: Minchan Kim minc...@kernel.org Cc: Michal Nazarewicz min...@mina86.com Cc: Naoya Horiguchi n-horigu...@ah.jp.nec.com Cc: Christoph Lameter c...@linux.com Cc: Rik van Riel r...@redhat.com Cc: Mel Gorman mgor...@suse.de Cc: Zhang Yanfei zhangyan...@cn.fujitsu.com Signed-off-by: Andrew Morton a...@linux-foundation.org Hello, Andrew. I forgot to mention that this should be merged for v3.18. :) Thanks. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: + mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch added to -mm tree
On 10/23/2014 10:15 AM, Joonsoo Kim wrote: On Tue, Oct 14, 2014 at 01:53:44PM -0700, a...@linux-foundation.org wrote: The patch titled Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range has been added to the -mm tree. Its filename is mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch Before you just go and hit reply, please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days -- From: Joonsoo Kim iamjoonsoo@lge.com Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range commit edc2ca612496 (mm, compaction: move pageblock checks up from isolate_migratepages_range()) commonizes isolate_migratepages variants and make them use isolate_migratepages_block(). isolate_migratepages_block() could stop the execution when enough pages are isolated, but, there is no code in isolate_migratepages_range() to handle this case. In the result, even if isolate_migratepages_block() returns prematurely without checking all pages in the range, isolate_migratepages_block() is called repeately on the following pageblock and some pages in the previous range are skipped to check. Then, CMA is failed frequently due to this fact. To fix this problem, this patch let isolate_migratepages_range() know the situation that enough pages are isolated and stop the isolation in that case. Note that isolate_migratepages() has no such problem, because, it always stops the isolation after just one call of isolate_migratepages_block(). Signed-off-by: Joonsoo Kim iamjoonsoo@lge.com Cc: Vlastimil Babka vba...@suse.cz Cc: David Rientjes rient...@google.com Cc: Minchan Kim minc...@kernel.org Cc: Michal Nazarewicz min...@mina86.com Cc: Naoya Horiguchi n-horigu...@ah.jp.nec.com Cc: Christoph Lameter c...@linux.com Cc: Rik van Riel r...@redhat.com Cc: Mel Gorman mgor...@suse.de Cc: Zhang Yanfei zhangyan...@cn.fujitsu.com Signed-off-by: Andrew Morton a...@linux-foundation.org Acked-by: Vlastimil Babka vba...@suse.cz Sorry for the trouble. But I think a more robust and future-proof fix would be a check such as: if (pfn block_end_pfn) break; This should catch any reason where isolate_migratepages_block() did not finish whole pageblock, and which was not fatal enough to return pfn==0. However currently this seems to happen only due to isolating too much, so your patch should work. So it's up to you if you want to make the check more generic now, or later after this bug is fixed for 3.18. Vlastimil Hello, Andrew. I forgot to mention that this should be merged for v3.18. :) Thanks. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: + mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch added to -mm tree
On Thu, Oct 23, 2014 at 10:39:45AM +0200, Vlastimil Babka wrote: On 10/23/2014 10:15 AM, Joonsoo Kim wrote: On Tue, Oct 14, 2014 at 01:53:44PM -0700, a...@linux-foundation.org wrote: The patch titled Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range has been added to the -mm tree. Its filename is mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch Before you just go and hit reply, please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days -- From: Joonsoo Kim iamjoonsoo@lge.com Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range commit edc2ca612496 (mm, compaction: move pageblock checks up from isolate_migratepages_range()) commonizes isolate_migratepages variants and make them use isolate_migratepages_block(). isolate_migratepages_block() could stop the execution when enough pages are isolated, but, there is no code in isolate_migratepages_range() to handle this case. In the result, even if isolate_migratepages_block() returns prematurely without checking all pages in the range, isolate_migratepages_block() is called repeately on the following pageblock and some pages in the previous range are skipped to check. Then, CMA is failed frequently due to this fact. To fix this problem, this patch let isolate_migratepages_range() know the situation that enough pages are isolated and stop the isolation in that case. Note that isolate_migratepages() has no such problem, because, it always stops the isolation after just one call of isolate_migratepages_block(). Signed-off-by: Joonsoo Kim iamjoonsoo@lge.com Cc: Vlastimil Babka vba...@suse.cz Cc: David Rientjes rient...@google.com Cc: Minchan Kim minc...@kernel.org Cc: Michal Nazarewicz min...@mina86.com Cc: Naoya Horiguchi n-horigu...@ah.jp.nec.com Cc: Christoph Lameter c...@linux.com Cc: Rik van Riel r...@redhat.com Cc: Mel Gorman mgor...@suse.de Cc: Zhang Yanfei zhangyan...@cn.fujitsu.com Signed-off-by: Andrew Morton a...@linux-foundation.org Acked-by: Vlastimil Babka vba...@suse.cz Sorry for the trouble. But I think a more robust and future-proof fix would be a check such as: if (pfn block_end_pfn) break; This should catch any reason where isolate_migratepages_block() did not finish whole pageblock, and which was not fatal enough to return pfn==0. However currently this seems to happen only due to isolating too much, so your patch should work. So it's up to you if you want to make the check more generic now, or later after this bug is fixed for 3.18. 'if (pfn block_end_pfn) break;' has one problem. If we have enough isolated pages and reach at block_end_pfn, we can't stop with above check. More proper check may be as following. 'if (pfn block_end_pfn || cc-nr_migratepages == COMPACT_CLUSTER_MAX) break;' But, as you mentioned, there is no case where 'pfn block_end_pfn' now, so I'd like to remain the patch as is. Thanks. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
