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Re: OOM detection regressions since 4.7

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  Re: OOM detection regressions since 4.7 Michal Hocko <mhocko@kernel.org> - 2016-08-22 11:40 +0200
    Re: OOM detection regressions since 4.7 Greg KH <gregkh@linuxfoundation.org> - 2016-08-22 12:20 +0200
      Re: OOM detection regressions since 4.7 Michal Hocko <mhocko@kernel.org> - 2016-08-22 13:00 +0200
        Re: OOM detection regressions since 4.7 Greg KH <gregkh@linuxfoundation.org> - 2016-08-22 15:40 +0200
          Re: OOM detection regressions since 4.7 Michal Hocko <mhocko@kernel.org> - 2016-08-22 15:50 +0200
            Re: OOM detection regressions since 4.7 Greg KH <gregkh@linuxfoundation.org> - 2016-08-22 16:10 +0200
            Re: OOM detection regressions since 4.7 Andrew Morton <akpm@linux-foundation.org> - 2016-08-23 00:10 +0200
              Re: OOM detection regressions since 4.7 Michal Hocko <mhocko@kernel.org> - 2016-08-23 11:00 +0200
                Re: OOM detection regressions since 4.7 Olaf Hering <olaf@aepfle.de> - 2016-08-25 09:30 +0200
                  Re: OOM detection regressions since 4.7 Olaf Hering <olaf@aepfle.de> - 2016-08-29 17:00 +0200
                    Re: OOM detection regressions since 4.7 Olaf Hering <olaf@aepfle.de> - 2016-08-29 17:00 +0200
                    Re: OOM detection regressions since 4.7 Michal Hocko <mhocko@kernel.org> - 2016-08-29 17:10 +0200
                      Re: OOM detection regressions since 4.7 Olaf Hering <olaf@aepfle.de> - 2016-08-29 18:10 +0200
                    Re: OOM detection regressions since 4.7 Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-29 19:30 +0200
                      Re: OOM detection regressions since 4.7 Jeff Layton <jlayton@poochiereds.net> - 2016-08-29 20:00 +0200
                Re: OOM detection regressions since 4.7 Michal Hocko <mhocko@kernel.org> - 2016-08-25 09:40 +0200
                  Re: OOM detection regressions since 4.7 Arkadiusz Miskiewicz <a.miskiewicz@gmail.com> - 2016-08-28 08:00 +0200
                Re: OOM detection regressions since 4.7 Ralf-Peter Rohbeck <Ralf-Peter.Rohbeck@quantum.com> - 2016-08-25 22:50 +0200
                  Re: OOM detection regressions since 4.7 Michal Hocko <mhocko@kernel.org> - 2016-08-26 08:30 +0200
                    Re: OOM detection regressions since 4.7 Ralf-Peter Rohbeck <Ralf-Peter.Rohbeck@quantum.com> - 2016-08-26 22:50 +0200

#1467503 — Re: OOM detection regressions since 4.7

[ups, fixing up Greg's email]

On Mon 22-08-16 11:32:49, Michal Hocko wrote:
> Hi, 
> there have been multiple reports [1][2][3][4][5] about pre-mature OOM
> killer invocations since 4.7 which contains oom detection rework. All of
> them were for order-2 (kernel stack) alloaction requests failing because
> of a high fragmentation and compaction failing to make any forward
> progress. While investigating this we have found out that the compaction
> just gives up too early. Vlastimil has been working on compaction
> improvement for quite some time and his series [6] is already sitting
> in mmotm tree. This already helps a lot because it drops some heuristics
> which are more aimed at lower latencies for high orders rather than
> reliability. Joonsoo has then identified further problem with too many
> blocks being marked as unmovable [7] and Vlastimil has prepared a patch
> on top of his series [8] which is also in the mmotm tree now.
> 
> That being said, the regression is real and should be fixed for 4.7
> stable users. [6][8] was reported to help and ooms are no longer
> reproducible. I know we are quite late (rc3) in 4.8 but I would vote
> for mergeing those patches and have them in 4.8. For 4.7 I would go
> with a partial revert of the detection rework for high order requests
> (see patch below). This patch is really trivial. If those compaction
> improvements are just too large for 4.8 then we can use the same patch
> as for 4.7 stable for now and revert it in 4.9 after compaction changes
> are merged.
> 
> Thoughts?
> 
> [1] http://lkml.kernel.org/r/20160731051121.GB307@x4
> [2] http://lkml.kernel.org/r/201608120901.41463.a.miskiewicz@gmail.com
> [3] http://lkml.kernel.org/r/20160801192620.GD31957@dhcp22.suse.cz
> [4] https://lists.opensuse.org/opensuse-kernel/2016-08/msg00021.html
> [5] https://bugzilla.opensuse.org/show_bug.cgi?id=994066
> [6] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
> [7] http://lkml.kernel.org/r/20160816031222.GC16913@js1304-P5Q-DELUXE
> [8] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz
> 
> ---
> From 899b738538de41295839dca2090a774bdd17acd2 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@suse.com>
> Date: Mon, 22 Aug 2016 10:52:06 +0200
> Subject: [PATCH] mm, oom: prevent pre-mature OOM killer invocation for high
>  order request
> 
> There have been several reports about pre-mature OOM killer invocation
> in 4.7 kernel when order-2 allocation request (for the kernel stack)
> invoked OOM killer even during basic workloads (light IO or even kernel
> compile on some filesystems). In all reported cases the memory is
> fragmented and there are no order-2+ pages available. There is usually
> a large amount of slab memory (usually dentries/inodes) and further
> debugging has shown that there are way too many unmovable blocks which
> are skipped during the compaction. Multiple reporters have confirmed that
> the current linux-next which includes [1] and [2] helped and OOMs are
> not reproducible anymore. A simpler fix for the stable is to simply
> ignore the compaction feedback and retry as long as there is a reclaim
> progress for high order requests which we used to do before. We already
> do that for CONFING_COMPACTION=n so let's reuse the same code when
> compaction is enabled as well.
> 
> [1] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
> [2] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz
> 
> Fixes: 0a0337e0d1d1 ("mm, oom: rework oom detection")
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  mm/page_alloc.c | 50 ++------------------------------------------------
>  1 file changed, 2 insertions(+), 48 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 8b3e1341b754..6e354199151b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3254,53 +3254,6 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
>  	return NULL;
>  }
>  
> -static inline bool
> -should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
> -		     enum compact_result compact_result, enum migrate_mode *migrate_mode,
> -		     int compaction_retries)
> -{
> -	int max_retries = MAX_COMPACT_RETRIES;
> -
> -	if (!order)
> -		return false;
> -
> -	/*
> -	 * compaction considers all the zone as desperately out of memory
> -	 * so it doesn't really make much sense to retry except when the
> -	 * failure could be caused by weak migration mode.
> -	 */
> -	if (compaction_failed(compact_result)) {
> -		if (*migrate_mode == MIGRATE_ASYNC) {
> -			*migrate_mode = MIGRATE_SYNC_LIGHT;
> -			return true;
> -		}
> -		return false;
> -	}
> -
> -	/*
> -	 * make sure the compaction wasn't deferred or didn't bail out early
> -	 * due to locks contention before we declare that we should give up.
> -	 * But do not retry if the given zonelist is not suitable for
> -	 * compaction.
> -	 */
> -	if (compaction_withdrawn(compact_result))
> -		return compaction_zonelist_suitable(ac, order, alloc_flags);
> -
> -	/*
> -	 * !costly requests are much more important than __GFP_REPEAT
> -	 * costly ones because they are de facto nofail and invoke OOM
> -	 * killer to move on while costly can fail and users are ready
> -	 * to cope with that. 1/4 retries is rather arbitrary but we
> -	 * would need much more detailed feedback from compaction to
> -	 * make a better decision.
> -	 */
> -	if (order > PAGE_ALLOC_COSTLY_ORDER)
> -		max_retries /= 4;
> -	if (compaction_retries <= max_retries)
> -		return true;
> -
> -	return false;
> -}
>  #else
>  static inline struct page *
>  __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> @@ -3311,6 +3264,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
>  	return NULL;
>  }
>  
> +#endif /* CONFIG_COMPACTION */
> +
>  static inline bool
>  should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
>  		     enum compact_result compact_result,
> @@ -3337,7 +3292,6 @@ should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_fla
>  	}
>  	return false;
>  }
> -#endif /* CONFIG_COMPACTION */
>  
>  /* Perform direct synchronous page reclaim */
>  static int
> -- 
> 2.8.1
> 
> -- 
> Michal Hocko
> SUSE Labs

-- 
Michal Hocko
SUSE Labs

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#1467526

On Mon, Aug 22, 2016 at 11:37:07AM +0200, Michal Hocko wrote:
> [ups, fixing up Greg's email]
> 
> On Mon 22-08-16 11:32:49, Michal Hocko wrote:
> > Hi, 
> > there have been multiple reports [1][2][3][4][5] about pre-mature OOM
> > killer invocations since 4.7 which contains oom detection rework. All of
> > them were for order-2 (kernel stack) alloaction requests failing because
> > of a high fragmentation and compaction failing to make any forward
> > progress. While investigating this we have found out that the compaction
> > just gives up too early. Vlastimil has been working on compaction
> > improvement for quite some time and his series [6] is already sitting
> > in mmotm tree. This already helps a lot because it drops some heuristics
> > which are more aimed at lower latencies for high orders rather than
> > reliability. Joonsoo has then identified further problem with too many
> > blocks being marked as unmovable [7] and Vlastimil has prepared a patch
> > on top of his series [8] which is also in the mmotm tree now.
> > 
> > That being said, the regression is real and should be fixed for 4.7
> > stable users. [6][8] was reported to help and ooms are no longer
> > reproducible. I know we are quite late (rc3) in 4.8 but I would vote
> > for mergeing those patches and have them in 4.8. For 4.7 I would go
> > with a partial revert of the detection rework for high order requests
> > (see patch below). This patch is really trivial. If those compaction
> > improvements are just too large for 4.8 then we can use the same patch
> > as for 4.7 stable for now and revert it in 4.9 after compaction changes
> > are merged.
> > 
> > Thoughts?
> > 
> > [1] http://lkml.kernel.org/r/20160731051121.GB307@x4
> > [2] http://lkml.kernel.org/r/201608120901.41463.a.miskiewicz@gmail.com
> > [3] http://lkml.kernel.org/r/20160801192620.GD31957@dhcp22.suse.cz
> > [4] https://lists.opensuse.org/opensuse-kernel/2016-08/msg00021.html
> > [5] https://bugzilla.opensuse.org/show_bug.cgi?id=994066
> > [6] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
> > [7] http://lkml.kernel.org/r/20160816031222.GC16913@js1304-P5Q-DELUXE
> > [8] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz
> > 
> > ---
> > From 899b738538de41295839dca2090a774bdd17acd2 Mon Sep 17 00:00:00 2001
> > From: Michal Hocko <mhocko@suse.com>
> > Date: Mon, 22 Aug 2016 10:52:06 +0200
> > Subject: [PATCH] mm, oom: prevent pre-mature OOM killer invocation for high
> >  order request
> > 
> > There have been several reports about pre-mature OOM killer invocation
> > in 4.7 kernel when order-2 allocation request (for the kernel stack)
> > invoked OOM killer even during basic workloads (light IO or even kernel
> > compile on some filesystems). In all reported cases the memory is
> > fragmented and there are no order-2+ pages available. There is usually
> > a large amount of slab memory (usually dentries/inodes) and further
> > debugging has shown that there are way too many unmovable blocks which
> > are skipped during the compaction. Multiple reporters have confirmed that
> > the current linux-next which includes [1] and [2] helped and OOMs are
> > not reproducible anymore. A simpler fix for the stable is to simply
> > ignore the compaction feedback and retry as long as there is a reclaim
> > progress for high order requests which we used to do before. We already
> > do that for CONFING_COMPACTION=n so let's reuse the same code when
> > compaction is enabled as well.
> > 
> > [1] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
> > [2] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz
> > 
> > Fixes: 0a0337e0d1d1 ("mm, oom: rework oom detection")
> > Signed-off-by: Michal Hocko <mhocko@suse.com>
> > ---
> >  mm/page_alloc.c | 50 ++------------------------------------------------
> >  1 file changed, 2 insertions(+), 48 deletions(-)

So, if this goes into Linus's tree, can you let stable@vger.kernel.org
know about it so we can add it to the 4.7-stable tree?  Otherwise
there's not much I can do here now, right?

thanks,

greg k-h

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#1467547

On Mon 22-08-16 06:05:28, Greg KH wrote:
> On Mon, Aug 22, 2016 at 11:37:07AM +0200, Michal Hocko wrote:
[...]
> > > From 899b738538de41295839dca2090a774bdd17acd2 Mon Sep 17 00:00:00 2001
> > > From: Michal Hocko <mhocko@suse.com>
> > > Date: Mon, 22 Aug 2016 10:52:06 +0200
> > > Subject: [PATCH] mm, oom: prevent pre-mature OOM killer invocation for high
> > >  order request
> > > 
> > > There have been several reports about pre-mature OOM killer invocation
> > > in 4.7 kernel when order-2 allocation request (for the kernel stack)
> > > invoked OOM killer even during basic workloads (light IO or even kernel
> > > compile on some filesystems). In all reported cases the memory is
> > > fragmented and there are no order-2+ pages available. There is usually
> > > a large amount of slab memory (usually dentries/inodes) and further
> > > debugging has shown that there are way too many unmovable blocks which
> > > are skipped during the compaction. Multiple reporters have confirmed that
> > > the current linux-next which includes [1] and [2] helped and OOMs are
> > > not reproducible anymore. A simpler fix for the stable is to simply
> > > ignore the compaction feedback and retry as long as there is a reclaim
> > > progress for high order requests which we used to do before. We already
> > > do that for CONFING_COMPACTION=n so let's reuse the same code when
> > > compaction is enabled as well.
> > > 
> > > [1] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
> > > [2] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz
> > > 
> > > Fixes: 0a0337e0d1d1 ("mm, oom: rework oom detection")
> > > Signed-off-by: Michal Hocko <mhocko@suse.com>
> > > ---
> > >  mm/page_alloc.c | 50 ++------------------------------------------------
> > >  1 file changed, 2 insertions(+), 48 deletions(-)
> 
> So, if this goes into Linus's tree, can you let stable@vger.kernel.org
> know about it so we can add it to the 4.7-stable tree?  Otherwise
> there's not much I can do here now, right?

My plan would be actually to not push this to Linus because we have a
proper fix for Linus tree. It is just that the fix is quite large and I
felt like the stable should get the most simple fix possible, which is
this partial revert. So, what I am trying to tell is to push a non-linus
patch to stable as it is simpler.
-- 
Michal Hocko
SUSE Labs

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#1467631

On Mon, Aug 22, 2016 at 12:54:41PM +0200, Michal Hocko wrote:
> On Mon 22-08-16 06:05:28, Greg KH wrote:
> > On Mon, Aug 22, 2016 at 11:37:07AM +0200, Michal Hocko wrote:
> [...]
> > > > From 899b738538de41295839dca2090a774bdd17acd2 Mon Sep 17 00:00:00 2001
> > > > From: Michal Hocko <mhocko@suse.com>
> > > > Date: Mon, 22 Aug 2016 10:52:06 +0200
> > > > Subject: [PATCH] mm, oom: prevent pre-mature OOM killer invocation for high
> > > >  order request
> > > > 
> > > > There have been several reports about pre-mature OOM killer invocation
> > > > in 4.7 kernel when order-2 allocation request (for the kernel stack)
> > > > invoked OOM killer even during basic workloads (light IO or even kernel
> > > > compile on some filesystems). In all reported cases the memory is
> > > > fragmented and there are no order-2+ pages available. There is usually
> > > > a large amount of slab memory (usually dentries/inodes) and further
> > > > debugging has shown that there are way too many unmovable blocks which
> > > > are skipped during the compaction. Multiple reporters have confirmed that
> > > > the current linux-next which includes [1] and [2] helped and OOMs are
> > > > not reproducible anymore. A simpler fix for the stable is to simply
> > > > ignore the compaction feedback and retry as long as there is a reclaim
> > > > progress for high order requests which we used to do before. We already
> > > > do that for CONFING_COMPACTION=n so let's reuse the same code when
> > > > compaction is enabled as well.
> > > > 
> > > > [1] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
> > > > [2] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz
> > > > 
> > > > Fixes: 0a0337e0d1d1 ("mm, oom: rework oom detection")
> > > > Signed-off-by: Michal Hocko <mhocko@suse.com>
> > > > ---
> > > >  mm/page_alloc.c | 50 ++------------------------------------------------
> > > >  1 file changed, 2 insertions(+), 48 deletions(-)
> > 
> > So, if this goes into Linus's tree, can you let stable@vger.kernel.org
> > know about it so we can add it to the 4.7-stable tree?  Otherwise
> > there's not much I can do here now, right?
> 
> My plan would be actually to not push this to Linus because we have a
> proper fix for Linus tree. It is just that the fix is quite large and I
> felt like the stable should get the most simple fix possible, which is
> this partial revert. So, what I am trying to tell is to push a non-linus
> patch to stable as it is simpler.

I _REALLY_ hate taking any patches that are not in Linus's tree as 90%
of the time (well, almost always), it ends up being wrong and hurting us
in the end.

What exactly are the commits that are in Linus's tree that resolve this
issue?

thanks,

greg k-h

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#1467632

On Mon 22-08-16 09:31:14, Greg KH wrote:
> On Mon, Aug 22, 2016 at 12:54:41PM +0200, Michal Hocko wrote:
> > On Mon 22-08-16 06:05:28, Greg KH wrote:
> > > On Mon, Aug 22, 2016 at 11:37:07AM +0200, Michal Hocko wrote:
> > [...]
> > > > > From 899b738538de41295839dca2090a774bdd17acd2 Mon Sep 17 00:00:00 2001
> > > > > From: Michal Hocko <mhocko@suse.com>
> > > > > Date: Mon, 22 Aug 2016 10:52:06 +0200
> > > > > Subject: [PATCH] mm, oom: prevent pre-mature OOM killer invocation for high
> > > > >  order request
> > > > > 
> > > > > There have been several reports about pre-mature OOM killer invocation
> > > > > in 4.7 kernel when order-2 allocation request (for the kernel stack)
> > > > > invoked OOM killer even during basic workloads (light IO or even kernel
> > > > > compile on some filesystems). In all reported cases the memory is
> > > > > fragmented and there are no order-2+ pages available. There is usually
> > > > > a large amount of slab memory (usually dentries/inodes) and further
> > > > > debugging has shown that there are way too many unmovable blocks which
> > > > > are skipped during the compaction. Multiple reporters have confirmed that
> > > > > the current linux-next which includes [1] and [2] helped and OOMs are
> > > > > not reproducible anymore. A simpler fix for the stable is to simply
> > > > > ignore the compaction feedback and retry as long as there is a reclaim
> > > > > progress for high order requests which we used to do before. We already
> > > > > do that for CONFING_COMPACTION=n so let's reuse the same code when
> > > > > compaction is enabled as well.
> > > > > 
> > > > > [1] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
> > > > > [2] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz
> > > > > 
> > > > > Fixes: 0a0337e0d1d1 ("mm, oom: rework oom detection")
> > > > > Signed-off-by: Michal Hocko <mhocko@suse.com>
> > > > > ---
> > > > >  mm/page_alloc.c | 50 ++------------------------------------------------
> > > > >  1 file changed, 2 insertions(+), 48 deletions(-)
> > > 
> > > So, if this goes into Linus's tree, can you let stable@vger.kernel.org
> > > know about it so we can add it to the 4.7-stable tree?  Otherwise
> > > there's not much I can do here now, right?
> > 
> > My plan would be actually to not push this to Linus because we have a
> > proper fix for Linus tree. It is just that the fix is quite large and I
> > felt like the stable should get the most simple fix possible, which is
> > this partial revert. So, what I am trying to tell is to push a non-linus
> > patch to stable as it is simpler.
> 
> I _REALLY_ hate taking any patches that are not in Linus's tree as 90%
> of the time (well, almost always), it ends up being wrong and hurting us
> in the end.

I do not like it either but if there is a simple and straightforward
workaround for stable while the upstream can go with the _proper_ fix
from the longer POV then I think this is perfectly justified. Stable
should be always about the simplest fix for the problem IMHO.

Of course, if Linus/Andrew doesn't like to take those compaction
improvements this late then I will ask to merge the partial revert to
Linus tree as well and then there is not much to discuss.

> What exactly are the commits that are in Linus's tree that resolve this
> issue?

The initial email in this thread has pointed to those patches. Please
note that some of its dependeces (mostly code cleanups) are already
merged and that backporting without them would make the backport harder
and more risky.
-- 
Michal Hocko
SUSE Labs

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#1467652

On Mon, Aug 22, 2016 at 03:42:28PM +0200, Michal Hocko wrote:
> On Mon 22-08-16 09:31:14, Greg KH wrote:
> > On Mon, Aug 22, 2016 at 12:54:41PM +0200, Michal Hocko wrote:
> > > On Mon 22-08-16 06:05:28, Greg KH wrote:
> > > > On Mon, Aug 22, 2016 at 11:37:07AM +0200, Michal Hocko wrote:
> > > [...]
> > > > > > From 899b738538de41295839dca2090a774bdd17acd2 Mon Sep 17 00:00:00 2001
> > > > > > From: Michal Hocko <mhocko@suse.com>
> > > > > > Date: Mon, 22 Aug 2016 10:52:06 +0200
> > > > > > Subject: [PATCH] mm, oom: prevent pre-mature OOM killer invocation for high
> > > > > >  order request
> > > > > > 
> > > > > > There have been several reports about pre-mature OOM killer invocation
> > > > > > in 4.7 kernel when order-2 allocation request (for the kernel stack)
> > > > > > invoked OOM killer even during basic workloads (light IO or even kernel
> > > > > > compile on some filesystems). In all reported cases the memory is
> > > > > > fragmented and there are no order-2+ pages available. There is usually
> > > > > > a large amount of slab memory (usually dentries/inodes) and further
> > > > > > debugging has shown that there are way too many unmovable blocks which
> > > > > > are skipped during the compaction. Multiple reporters have confirmed that
> > > > > > the current linux-next which includes [1] and [2] helped and OOMs are
> > > > > > not reproducible anymore. A simpler fix for the stable is to simply
> > > > > > ignore the compaction feedback and retry as long as there is a reclaim
> > > > > > progress for high order requests which we used to do before. We already
> > > > > > do that for CONFING_COMPACTION=n so let's reuse the same code when
> > > > > > compaction is enabled as well.
> > > > > > 
> > > > > > [1] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
> > > > > > [2] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz
> > > > > > 
> > > > > > Fixes: 0a0337e0d1d1 ("mm, oom: rework oom detection")
> > > > > > Signed-off-by: Michal Hocko <mhocko@suse.com>
> > > > > > ---
> > > > > >  mm/page_alloc.c | 50 ++------------------------------------------------
> > > > > >  1 file changed, 2 insertions(+), 48 deletions(-)
> > > > 
> > > > So, if this goes into Linus's tree, can you let stable@vger.kernel.org
> > > > know about it so we can add it to the 4.7-stable tree?  Otherwise
> > > > there's not much I can do here now, right?
> > > 
> > > My plan would be actually to not push this to Linus because we have a
> > > proper fix for Linus tree. It is just that the fix is quite large and I
> > > felt like the stable should get the most simple fix possible, which is
> > > this partial revert. So, what I am trying to tell is to push a non-linus
> > > patch to stable as it is simpler.
> > 
> > I _REALLY_ hate taking any patches that are not in Linus's tree as 90%
> > of the time (well, almost always), it ends up being wrong and hurting us
> > in the end.
> 
> I do not like it either but if there is a simple and straightforward
> workaround for stable while the upstream can go with the _proper_ fix
> from the longer POV then I think this is perfectly justified. Stable
> should be always about the simplest fix for the problem IMHO.

No, stable should always be "what is in Linus's tree to get it fixed."

Again, almost every time we try to "just do this simple thing instead"
in a stable tree, it ends up being broken somehow.  We have the history
to back this up, look at our archives.

I'll gladly take 10+ patches to resolve something, _if_ it actually
resolves something.

But, if we argue about it for a month or so, then we don't have to worry
about it as everyone will be using 4.8 :)

> Of course, if Linus/Andrew doesn't like to take those compaction
> improvements this late then I will ask to merge the partial revert to
> Linus tree as well and then there is not much to discuss.

Ok, let me know how it goes and we can see what to do.

thanks.

greg k-h

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#1468089

On Mon, 22 Aug 2016 15:42:28 +0200 Michal Hocko <mhocko@kernel.org> wrote:

> Of course, if Linus/Andrew doesn't like to take those compaction
> improvements this late then I will ask to merge the partial revert to
> Linus tree as well and then there is not much to discuss.

This sounds like the prudent option.  Can we get 4.8 working
well-enough, backport that into 4.7.x and worry about the fancier stuff
for 4.9?

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#1468407

On Mon 22-08-16 15:05:17, Andrew Morton wrote:
> On Mon, 22 Aug 2016 15:42:28 +0200 Michal Hocko <mhocko@kernel.org> wrote:
> 
> > Of course, if Linus/Andrew doesn't like to take those compaction
> > improvements this late then I will ask to merge the partial revert to
> > Linus tree as well and then there is not much to discuss.
> 
> This sounds like the prudent option.  Can we get 4.8 working
> well-enough, backport that into 4.7.x and worry about the fancier stuff
> for 4.9?

OK, fair enough.

I would really appreciate if the original reporters could retest with
this patch on top of the current Linus tree. The stable backport posted
earlier doesn't apply on the current master cleanly but the change is
essentially same. mmotm tree then can revert this patch before Vlastimil
series is applied because that code is touching the currently removed
code.
---
From 90b6b282bede7966fb6c830a6d012d2239ac40e4 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Mon, 22 Aug 2016 10:52:06 +0200
Subject: [PATCH] mm, oom: prevent pre-mature OOM killer invocation for high
 order request

There have been several reports about pre-mature OOM killer invocation
in 4.7 kernel when order-2 allocation request (for the kernel stack)
invoked OOM killer even during basic workloads (light IO or even kernel
compile on some filesystems). In all reported cases the memory is
fragmented and there are no order-2+ pages available. There is usually
a large amount of slab memory (usually dentries/inodes) and further
debugging has shown that there are way too many unmovable blocks which
are skipped during the compaction. Multiple reporters have confirmed that
the current linux-next which includes [1] and [2] helped and OOMs are
not reproducible anymore.

A simpler fix for the late rc and stable is to simply ignore the
compaction feedback and retry as long as there is a reclaim progress
and we are not getting OOM for order-0 pages. We already do that for
CONFING_COMPACTION=n so let's reuse the same code when compaction is
enabled as well.

[1] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
[2] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz

Fixes: 0a0337e0d1d1 ("mm, oom: rework oom detection")
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/page_alloc.c | 51 ++-------------------------------------------------
 1 file changed, 2 insertions(+), 49 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3fbe73a6fe4b..7791a03f8deb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3137,54 +3137,6 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 	return NULL;
 }
 
-static inline bool
-should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
-		     enum compact_result compact_result,
-		     enum compact_priority *compact_priority,
-		     int compaction_retries)
-{
-	int max_retries = MAX_COMPACT_RETRIES;
-
-	if (!order)
-		return false;
-
-	/*
-	 * compaction considers all the zone as desperately out of memory
-	 * so it doesn't really make much sense to retry except when the
-	 * failure could be caused by insufficient priority
-	 */
-	if (compaction_failed(compact_result)) {
-		if (*compact_priority > MIN_COMPACT_PRIORITY) {
-			(*compact_priority)--;
-			return true;
-		}
-		return false;
-	}
-
-	/*
-	 * make sure the compaction wasn't deferred or didn't bail out early
-	 * due to locks contention before we declare that we should give up.
-	 * But do not retry if the given zonelist is not suitable for
-	 * compaction.
-	 */
-	if (compaction_withdrawn(compact_result))
-		return compaction_zonelist_suitable(ac, order, alloc_flags);
-
-	/*
-	 * !costly requests are much more important than __GFP_REPEAT
-	 * costly ones because they are de facto nofail and invoke OOM
-	 * killer to move on while costly can fail and users are ready
-	 * to cope with that. 1/4 retries is rather arbitrary but we
-	 * would need much more detailed feedback from compaction to
-	 * make a better decision.
-	 */
-	if (order > PAGE_ALLOC_COSTLY_ORDER)
-		max_retries /= 4;
-	if (compaction_retries <= max_retries)
-		return true;
-
-	return false;
-}
 #else
 static inline struct page *
 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
@@ -3195,6 +3147,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 	return NULL;
 }
 
+#endif /* CONFIG_COMPACTION */
+
 static inline bool
 should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
 		     enum compact_result compact_result,
@@ -3221,7 +3175,6 @@ should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_fla
 	}
 	return false;
 }
-#endif /* CONFIG_COMPACTION */
 
 /* Perform direct synchronous page reclaim */
 static int
-- 
2.8.1


-- 
Michal Hocko
SUSE Labs

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#1469907

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On Thu, Aug 25, Michal Hocko wrote:

> Any luck with the testing of this patch?

Not this week, sorry.

Olaf

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#1471899

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On Thu, Aug 25, Olaf Hering wrote:

> On Thu, Aug 25, Michal Hocko wrote:
> 
> > Any luck with the testing of this patch?

I ran rc3 for a few hours on Friday amd FireFox was not killed.
Now rc3 is running for a day with the usual workload and FireFox is
still running.

Today I noticed the nfsserver was disabled, probably since months already.
Starting it gives a OOM, not sure if this is new with 4.7+.
Full dmesg attached.


[    0.000000] Linux version 4.8.0-rc3-3.bug994066-default (geeko@buildhost) (gcc version 6.1.1 20160815 [gcc-6-branch revision 239479] (SUSE Linux) ) #1 SMP PREEMPT Mon Aug 22 14:52:18 UTC 2016 (c0d2ef5)

[64378.582489] tun: Universal TUN/TAP device driver, 1.6
[64378.582493] tun: (C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>
[93347.645123] RPC: Registered named UNIX socket transport module.
[93347.645128] RPC: Registered udp transport module.
[93347.645130] RPC: Registered tcp transport module.
[93347.645132] RPC: Registered tcp NFSv4.1 backchannel transport module.
[93348.227828] Installing knfsd (copyright (C) 1996 okir@monad.swb.de).
[93348.306369] modprobe: page allocation failure: order:4, mode:0x26040c0(GFP_KERNEL|__GFP_COMP|__GFP_NOTRACK)
[93348.306379] CPU: 2 PID: 30467 Comm: modprobe Not tainted 4.8.0-rc3-3.bug994066-default #1
[93348.306382] Hardware name: Hewlett-Packard HP ProBook 6555b/1455, BIOS 68DTM Ver. F.21 06/14/2012
[93348.306386]  0000000000000000 ffffffff813a2952 0000000000000004 ffff88003fb6ba30
[93348.306394]  ffffffff81198a4b 026040c00000000f 026040c000000001 ffff88003fb6c000
[93348.306400]  0000000000000004 ffff88003fb6baac 00000000026040c0 0000000000000040
[93348.306406] Call Trace:
[93348.306437]  [<ffffffff8102eefe>] dump_trace+0x5e/0x310
[93348.306449]  [<ffffffff8102f2cb>] show_stack_log_lvl+0x11b/0x1a0
[93348.306459]  [<ffffffff81030001>] show_stack+0x21/0x40
[93348.306468]  [<ffffffff813a2952>] dump_stack+0x5c/0x7a
[93348.306478]  [<ffffffff81198a4b>] warn_alloc_failed+0xdb/0x150
[93348.306490]  [<ffffffff81198cef>] __alloc_pages_slowpath+0x1af/0xa10
[93348.306501]  [<ffffffff811997a0>] __alloc_pages_nodemask+0x250/0x290
[93348.306511]  [<ffffffff811f1c3d>] cache_grow_begin+0x8d/0x540
[93348.306520]  [<ffffffff811f23d1>] fallback_alloc+0x161/0x200
[93348.306530]  [<ffffffff811f43f2>] __kmalloc+0x1d2/0x570
[93348.306589]  [<ffffffffa08f025a>] nfsd_reply_cache_init+0xaa/0x110 [nfsd]
[93348.306649]  [<ffffffffa093f1b6>] init_nfsd+0x56/0xea0 [nfsd]
[93348.306664]  [<ffffffff8100218b>] do_one_initcall+0x4b/0x180
[93348.306674]  [<ffffffff8118e119>] do_init_module+0x5b/0x1fe
[93348.306684]  [<ffffffff81105395>] load_module+0x1a75/0x1d00
[93348.306695]  [<ffffffff81105804>] SYSC_finit_module+0xa4/0xe0
[93348.306705]  [<ffffffff816d2cb6>] entry_SYSCALL_64_fastpath+0x1e/0xa8
[93348.313626] DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x1e/0xa8

[93348.313629] Leftover inexact backtrace:

[93348.313691] Mem-Info:
[93348.313704] active_anon:467209 inactive_anon:125491 isolated_anon:0
                active_file:264880 inactive_file:166389 isolated_file:0
                unevictable:8 dirty:250 writeback:0 unstable:0
                slab_reclaimable:796425 slab_unreclaimable:34803
                mapped:54783 shmem:24119 pagetables:9083 bounce:0
                free:51321 free_pcp:68 free_cma:0
[93348.313717] Node 0 active_anon:1868836kB inactive_anon:501964kB active_file:1059520kB inactive_file:665556kB unevictable:32kB isolated(anon):0kB isolated(file):0kB mapped:219132kB dirty:1000kB writeback:0kB shmem:0kB shmem_thp: 0kB shmem_pmdmapped: 749568kB anon_thp: 96476kB writeback_tmp:0kB unstable:0kB pages_scanned:24 all_unreclaimable? no
[93348.313719] Node 0 DMA free:15908kB min:136kB low:168kB high:200kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15992kB managed:15908kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
[93348.313729] lowmem_reserve[]: 0 2626 7621 7621 7621
[93348.313745] Node 0 DMA32 free:133192kB min:23244kB low:29052kB high:34860kB active_anon:642152kB inactive_anon:119848kB active_file:257900kB inactive_file:116560kB unevictable:0kB writepending:292kB present:2847412kB managed:2766832kB mlocked:0kB slab_reclaimable:1418576kB slab_unreclaimable:39004kB kernel_stack:256kB pagetables:1448kB bounce:0kB free_pcp:128kB local_pcp:0kB free_cma:0kB
[93348.313755] lowmem_reserve[]: 0 0 4994 4994 4994
[93348.313762] Node 0 Normal free:56184kB min:44200kB low:55248kB high:66296kB active_anon:1226576kB inactive_anon:382200kB active_file:801508kB inactive_file:548992kB unevictable:32kB writepending:536kB present:5242880kB managed:5114880kB mlocked:32kB slab_reclaimable:1767124kB slab_unreclaimable:100208kB kernel_stack:9104kB pagetables:34884kB bounce:0kB free_pcp:144kB local_pcp:0kB free_cma:0kB
[93348.313771] lowmem_reserve[]: 0 0 0 0 0
[93348.313778] Node 0 DMA: 1*4kB (U) 0*8kB 0*16kB 1*32kB (U) 2*64kB (U) 1*128kB (U) 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) = 15908kB
[93348.313803] Node 0 DMA32: 13633*4kB (UME) 8035*8kB (UME) 890*16kB (UME) 10*32kB (U) 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 133372kB
[93348.313822] Node 0 Normal: 14003*4kB (UME) 25*8kB (UME) 2*16kB (UM) 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 56244kB
[93348.313843] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
[93348.313846] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
[93348.313848] 457622 total pagecache pages
[93348.313850] 2194 pages in swap cache
[93348.313853] Swap cache stats: add 60025, delete 57831, find 17283/19516
[93348.313854] Free swap  = 8170356kB
[93348.313856] Total swap = 8384508kB
[93348.313858] 2026571 pages RAM
[93348.313859] 0 pages HighMem/MovableOnly
[93348.313860] 52166 pages reserved
[93348.313861] 0 pages hwpoisoned
[93348.313865] nfsd: failed to allocate reply cache

Olaf

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#1471900

[Multipart message — attachments visible in raw view] — view raw

On Mon, Aug 29, Olaf Hering wrote:

> Full dmesg attached.

Now..

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#1471902

On Mon 29-08-16 16:52:03, Olaf Hering wrote:
> On Thu, Aug 25, Olaf Hering wrote:
> 
> > On Thu, Aug 25, Michal Hocko wrote:
> > 
> > > Any luck with the testing of this patch?
> 
> I ran rc3 for a few hours on Friday amd FireFox was not killed.
> Now rc3 is running for a day with the usual workload and FireFox is
> still running.

Is the patch
(http://lkml.kernel.org/r/20160823074339.GB23577@dhcp22.suse.cz) applied?

> Today I noticed the nfsserver was disabled, probably since months already.
> Starting it gives a OOM, not sure if this is new with 4.7+.
> Full dmesg attached.
> [93348.306369] modprobe: page allocation failure: order:4, mode:0x26040c0(GFP_KERNEL|__GFP_COMP|__GFP_NOTRACK)

ok so order-4 (COSTLY allocation) has failed because

[...]
> [93348.313778] Node 0 DMA: 1*4kB (U) 0*8kB 0*16kB 1*32kB (U) 2*64kB (U) 1*128kB (U) 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) = 15908kB
> [93348.313803] Node 0 DMA32: 13633*4kB (UME) 8035*8kB (UME) 890*16kB (UME) 10*32kB (U) 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 133372kB
> [93348.313822] Node 0 Normal: 14003*4kB (UME) 25*8kB (UME) 2*16kB (UM) 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 56244kB

the memory is too fragmented for such a large allocation. Failing
order-4 requests is not so severe because we do not invoke the oom
killer if they fail. Especially without GFP_REPEAT we do not even try
too hard. Recent oom detection changes shouldn't change this behavior.

-- 
Michal Hocko
SUSE Labs

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#1471946

[Multipart message — attachments visible in raw view] — view raw

On Mon, Aug 29, Michal Hocko wrote:

> On Mon 29-08-16 16:52:03, Olaf Hering wrote:
> > I ran rc3 for a few hours on Friday amd FireFox was not killed.
> > Now rc3 is running for a day with the usual workload and FireFox is
> > still running.
> Is the patch
> (http://lkml.kernel.org/r/20160823074339.GB23577@dhcp22.suse.cz) applied?

Yes.

Tested-by: Olaf Hering <olaf@aepfle.de>

Olaf

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#1471995

On Mon, Aug 29, 2016 at 7:52 AM, Olaf Hering <olaf@aepfle.de> wrote:
>
> Today I noticed the nfsserver was disabled, probably since months already.
> Starting it gives a OOM, not sure if this is new with 4.7+.

That's not an oom, that's just an allocation failure.

And with order-4, that's actually pretty normal. Nobody should use
order-4 (that's 16 contiguous pages, fragmentation can easily make
that hard - *much* harder than the small order-2 or order-2 cases that
we should largely be able to rely on).

In fact, people who do multi-order allocations should always have a
fallback, and use __GFP_NOWARN.

> [93348.306406] Call Trace:
> [93348.306490]  [<ffffffff81198cef>] __alloc_pages_slowpath+0x1af/0xa10
> [93348.306501]  [<ffffffff811997a0>] __alloc_pages_nodemask+0x250/0x290
> [93348.306511]  [<ffffffff811f1c3d>] cache_grow_begin+0x8d/0x540
> [93348.306520]  [<ffffffff811f23d1>] fallback_alloc+0x161/0x200
> [93348.306530]  [<ffffffff811f43f2>] __kmalloc+0x1d2/0x570
> [93348.306589]  [<ffffffffa08f025a>] nfsd_reply_cache_init+0xaa/0x110 [nfsd]

Hmm. That's kmalloc itself falling back after already failing to grow
the slab cache earlier (the earlier allocations *were* done with
NOWARN afaik).

It does look like nfsdstarts out by allocating the hash table with one
single fairly big allocation, and has no fallback position.

I suspect the code expects to be started at boot time, when this just
isn't an issue. The fact that you loaded the nfsd kernel module with
memory already fragmented after heavy use is likely why nobody else
has seen this.

Adding the nfsd people to the cc, because just from a robustness
standpoint I suspect it would be better if the code did something like

 (a) shrink the hash table if the allocation fails (we've got some
examples of that elsewhere)

or

 (b) fall back on a vmalloc allocation (that's certainly the simpler model)

We do have a "kvfree()" helper function for the "free either a kmalloc
or vmalloc allocation" but we don't actually have a good helper
pattern for the allocation side. People just do it by hand, at least
partly because we have so many different ways to allocate things -
zeroing, non-zeroing, node-specific or not, atomic or not (atomic
cannot fall back to vmalloc, obviously) etc etc.

Bruce, Jeff, comments?

             Linus

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#1472015

On Mon, 2016-08-29 at 10:28 -0700, Linus Torvalds wrote:
> > On Mon, Aug 29, 2016 at 7:52 AM, Olaf Hering <olaf@aepfle.de> wrote:
> > 
> > 
> > Today I noticed the nfsserver was disabled, probably since months already.
> > Starting it gives a OOM, not sure if this is new with 4.7+.
> 
> That's not an oom, that's just an allocation failure.
> 
> And with order-4, that's actually pretty normal. Nobody should use
> order-4 (that's 16 contiguous pages, fragmentation can easily make
> that hard - *much* harder than the small order-2 or order-2 cases that
> we should largely be able to rely on).
> 
> In fact, people who do multi-order allocations should always have a
> fallback, and use __GFP_NOWARN.
> 
> > 
> > [93348.306406] Call Trace:
> > [93348.306490]  [<ffffffff81198cef>] __alloc_pages_slowpath+0x1af/0xa10
> > [93348.306501]  [<ffffffff811997a0>] __alloc_pages_nodemask+0x250/0x290
> > [93348.306511]  [<ffffffff811f1c3d>] cache_grow_begin+0x8d/0x540
> > [93348.306520]  [<ffffffff811f23d1>] fallback_alloc+0x161/0x200
> > [93348.306530]  [<ffffffff811f43f2>] __kmalloc+0x1d2/0x570
> > [93348.306589]  [<ffffffffa08f025a>] nfsd_reply_cache_init+0xaa/0x110 [nfsd]
> 
> Hmm. That's kmalloc itself falling back after already failing to grow
> the slab cache earlier (the earlier allocations *were* done with
> NOWARN afaik).
> 
> It does look like nfsdstarts out by allocating the hash table with one
> single fairly big allocation, and has no fallback position.
> 
> I suspect the code expects to be started at boot time, when this just
> isn't an issue. The fact that you loaded the nfsd kernel module with
> memory already fragmented after heavy use is likely why nobody else
> has seen this.
> 
> Adding the nfsd people to the cc, because just from a robustness
> standpoint I suspect it would be better if the code did something like
> 
>  (a) shrink the hash table if the allocation fails (we've got some
> examples of that elsewhere)
> 
> or
> 
>  (b) fall back on a vmalloc allocation (that's certainly the simpler model)
> 
> We do have a "kvfree()" helper function for the "free either a kmalloc
> or vmalloc allocation" but we don't actually have a good helper
> pattern for the allocation side. People just do it by hand, at least
> partly because we have so many different ways to allocate things -
> zeroing, non-zeroing, node-specific or not, atomic or not (atomic
> cannot fall back to vmalloc, obviously) etc etc.
> 
> Bruce, Jeff, comments?
> 
>              Linus

Yeah, that makes total sense.

Hmm...we _do_ already auto-size the hash at init time already, so
shrinking it downward and retrying if the allocation fails wouldn't be
hard to do. Maybe I can just cut it in half and throw a pr_warn to tell
the admin in that case.

In any case...I'll take a look at how we can improve it.

Thanks for the heads-up!
-- 
Jeff Layton <jlayton@poochiereds.net>

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#1469918

On Tue 23-08-16 09:43:39, Michal Hocko wrote:
> On Mon 22-08-16 15:05:17, Andrew Morton wrote:
> > On Mon, 22 Aug 2016 15:42:28 +0200 Michal Hocko <mhocko@kernel.org> wrote:
> > 
> > > Of course, if Linus/Andrew doesn't like to take those compaction
> > > improvements this late then I will ask to merge the partial revert to
> > > Linus tree as well and then there is not much to discuss.
> > 
> > This sounds like the prudent option.  Can we get 4.8 working
> > well-enough, backport that into 4.7.x and worry about the fancier stuff
> > for 4.9?
> 
> OK, fair enough.
> 
> I would really appreciate if the original reporters could retest with
> this patch on top of the current Linus tree.

Any luck with the testing of this patch?
-- 
Michal Hocko
SUSE Labs

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#1471276

On Thursday 25 of August 2016, Michal Hocko wrote:
> On Tue 23-08-16 09:43:39, Michal Hocko wrote:
> > On Mon 22-08-16 15:05:17, Andrew Morton wrote:
> > > On Mon, 22 Aug 2016 15:42:28 +0200 Michal Hocko <mhocko@kernel.org> 
wrote:
> > > > Of course, if Linus/Andrew doesn't like to take those compaction
> > > > improvements this late then I will ask to merge the partial revert to
> > > > Linus tree as well and then there is not much to discuss.
> > > 
> > > This sounds like the prudent option.  Can we get 4.8 working
> > > well-enough, backport that into 4.7.x and worry about the fancier stuff
> > > for 4.9?
> > 
> > OK, fair enough.
> > 
> > I would really appreciate if the original reporters could retest with
> > this patch on top of the current Linus tree.
> 
> Any luck with the testing of this patch?

Here my "rm -rf && cp -al" 10x in parallel test finished without OOM, so

Tested-by: Arkadiusz Miśkiewicz <arekm@maven.pl>

-- 
Arkadiusz Miśkiewicz, arekm / ( maven.pl | pld-linux.org )

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#1470410

On 23.08.2016 00:43, Michal Hocko wrote:
> OK, fair enough.
> I would really appreciate if the original reporters could retest with
> this patch on top of the current Linus tree. The stable backport posted
> earlier doesn't apply on the current master cleanly but the change is
> essentially same. mmotm tree then can revert this patch before Vlastimil
> series is applied because that code is touching the currently removed
> code.
> ---
>  From 90b6b282bede7966fb6c830a6d012d2239ac40e4 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@suse.com>
> Date: Mon, 22 Aug 2016 10:52:06 +0200
> Subject: [PATCH] mm, oom: prevent pre-mature OOM killer invocation for high
>   order request
>
> There have been several reports about pre-mature OOM killer invocation
> in 4.7 kernel when order-2 allocation request (for the kernel stack)
> invoked OOM killer even during basic workloads (light IO or even kernel
> compile on some filesystems). In all reported cases the memory is
> fragmented and there are no order-2+ pages available. There is usually
> a large amount of slab memory (usually dentries/inodes) and further
> debugging has shown that there are way too many unmovable blocks which
> are skipped during the compaction. Multiple reporters have confirmed that
> the current linux-next which includes [1] and [2] helped and OOMs are
> not reproducible anymore.
>
> A simpler fix for the late rc and stable is to simply ignore the
> compaction feedback and retry as long as there is a reclaim progress
> and we are not getting OOM for order-0 pages. We already do that for
> CONFING_COMPACTION=n so let's reuse the same code when compaction is
> enabled as well.
>
> [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_20160810091226.6709-2D1-2Dvbabka-40suse.cz&d=DQIBAg&c=8S5idjlO_n28Ko3lg6lskTMwneSC-WqZ5EBTEEvDlkg&r=yGQdEpZknbtYvR0TyhkCGu-ifLklIvXIf740poRFltQ&m=RnSShi4nOuCcTfoBOsx8P8OCPnA5R6zXLo9uZ2RBNjM&s=sJBmU_ySuE2OhXkEeFyTfUr05xjB-mO4aQ5yl4w8z1M&e=
> [2] https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_f7a9ea9d-2Dbb88-2Dbfd6-2De340-2D3a933559305a-40suse.cz&d=DQIBAg&c=8S5idjlO_n28Ko3lg6lskTMwneSC-WqZ5EBTEEvDlkg&r=yGQdEpZknbtYvR0TyhkCGu-ifLklIvXIf740poRFltQ&m=RnSShi4nOuCcTfoBOsx8P8OCPnA5R6zXLo9uZ2RBNjM&s=9oXRJsI8kr1rfMU9tAb9q0-8YlBCZO0XCCFRo0ASjlg&e=
>
> Fixes: 0a0337e0d1d1 ("mm, oom: rework oom detection")
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>   mm/page_alloc.c | 51 ++-------------------------------------------------
>   1 file changed, 2 insertions(+), 49 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3fbe73a6fe4b..7791a03f8deb 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3137,54 +3137,6 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
>   	return NULL;
>   }
>   
> -static inline bool
> -should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
> -		     enum compact_result compact_result,
> -		     enum compact_priority *compact_priority,
> -		     int compaction_retries)
> -{
> -	int max_retries = MAX_COMPACT_RETRIES;
> -
> -	if (!order)
> -		return false;
> -
> -	/*
> -	 * compaction considers all the zone as desperately out of memory
> -	 * so it doesn't really make much sense to retry except when the
> -	 * failure could be caused by insufficient priority
> -	 */
> -	if (compaction_failed(compact_result)) {
> -		if (*compact_priority > MIN_COMPACT_PRIORITY) {
> -			(*compact_priority)--;
> -			return true;
> -		}
> -		return false;
> -	}
> -
> -	/*
> -	 * make sure the compaction wasn't deferred or didn't bail out early
> -	 * due to locks contention before we declare that we should give up.
> -	 * But do not retry if the given zonelist is not suitable for
> -	 * compaction.
> -	 */
> -	if (compaction_withdrawn(compact_result))
> -		return compaction_zonelist_suitable(ac, order, alloc_flags);
> -
> -	/*
> -	 * !costly requests are much more important than __GFP_REPEAT
> -	 * costly ones because they are de facto nofail and invoke OOM
> -	 * killer to move on while costly can fail and users are ready
> -	 * to cope with that. 1/4 retries is rather arbitrary but we
> -	 * would need much more detailed feedback from compaction to
> -	 * make a better decision.
> -	 */
> -	if (order > PAGE_ALLOC_COSTLY_ORDER)
> -		max_retries /= 4;
> -	if (compaction_retries <= max_retries)
> -		return true;
> -
> -	return false;
> -}
>   #else
>   static inline struct page *
>   __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> @@ -3195,6 +3147,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
>   	return NULL;
>   }
>   
> +#endif /* CONFIG_COMPACTION */
> +
>   static inline bool
>   should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
>   		     enum compact_result compact_result,
> @@ -3221,7 +3175,6 @@ should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_fla
>   	}
>   	return false;
>   }
> -#endif /* CONFIG_COMPACTION */
>   
>   /* Perform direct synchronous page reclaim */
>   static int

This worked for me for about 12 hours of my torture test. Logs are at 
https://filebin.net/2rfah407nbhzs69e/OOM_4.8.0-rc2_p1.tar.bz2.


Ralf-Peter


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#1470561

On Thu 25-08-16 13:30:23, Ralf-Peter Rohbeck wrote:
[...]
> This worked for me for about 12 hours of my torture test. Logs are at
> https://filebin.net/2rfah407nbhzs69e/OOM_4.8.0-rc2_p1.tar.bz2.

Thanks! Can we add your
Tested-by: Ralf-Peter Rohbeck <Ralf-Peter.Rohbeck@quantum.com>

to the patch?
-- 
Michal Hocko
SUSE Labs

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#1470989

On 25.08.2016 23:26, Michal Hocko wrote:
> On Thu 25-08-16 13:30:23, Ralf-Peter Rohbeck wrote:
> [...]
>> This worked for me for about 12 hours of my torture test. Logs are at
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__filebin.net_2rfah407nbhzs69e_OOM-5F4.8.0-2Drc2-5Fp1.tar.bz2&d=DQIBAg&c=8S5idjlO_n28Ko3lg6lskTMwneSC-WqZ5EBTEEvDlkg&r=yGQdEpZknbtYvR0TyhkCGu-ifLklIvXIf740poRFltQ&m=xBE9zOUuzzrfyIgW70g1kmSzqiGPNXjBnN_zvF4eStQ&s=jdGSxmrQNhIx4cjVDsyyAA0K83hANgWXu1aFBDh_1B4&e= .
> Thanks! Can we add your
> Tested-by: Ralf-Peter Rohbeck <Ralf-Peter.Rohbeck@quantum.com>
>
> to the patch?

Sure.


Ralf-Peter


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The information contained in this transmission may be confidential. Any disclosure, copying, or further distribution of confidential information is not permitted unless such privilege is explicitly granted in writing by Quantum. Quantum reserves the right to have electronic communications, including email and attachments, sent across its networks filtered through anti virus and spam software programs and retain such messages in order to comply with applicable data security and retention requirements. Quantum is not responsible for the proper and complete transmission of the substance of this communication or for any delay in its receipt.

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