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From: Michal Hocko <mhocko@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>, NeilBrown <neilb@suse.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org, Christoph Hellwig <hch@infradead.org>,
	"Darrick J. Wong" <darrick.wong@oracle.com>
Subject: Re: [PATCH 3/6] xfs: map KM_MAYFAIL to __GFP_RETRY_MAYFAIL
Date: Tue, 27 Jun 2017 10:49:50 +0200	[thread overview]
Message-ID: <20170627084950.GI28072@dhcp22.suse.cz> (raw)
In-Reply-To: <20170623085345.11304-4-mhocko@kernel.org>

Christoph, Darrick
could you have a look at this patch please? Andrew has put it into mmotm
but I definitely do not want it passes your attention.

On Fri 23-06-17 10:53:42, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> KM_MAYFAIL didn't have any suitable GFP_FOO counterpart until recently
> so it relied on the default page allocator behavior for the given set
> of flags. This means that small allocations actually never failed.
> 
> Now that we have __GFP_RETRY_MAYFAIL flag which works independently on the
> allocation request size we can map KM_MAYFAIL to it. The allocator will
> try as hard as it can to fulfill the request but fails eventually if
> the progress cannot be made. It does so without triggering the OOM
> killer which can be seen as an improvement because KM_MAYFAIL users
> should be able to deal with allocation failures.
> 
> Cc: Darrick J. Wong <darrick.wong@oracle.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  fs/xfs/kmem.h | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h
> index d6ea520162b2..4d85992d75b2 100644
> --- a/fs/xfs/kmem.h
> +++ b/fs/xfs/kmem.h
> @@ -54,6 +54,16 @@ kmem_flags_convert(xfs_km_flags_t flags)
>  			lflags &= ~__GFP_FS;
>  	}
>  
> +	/*
> +	 * Default page/slab allocator behavior is to retry for ever
> +	 * for small allocations. We can override this behavior by using
> +	 * __GFP_RETRY_MAYFAIL which will tell the allocator to retry as long
> +	 * as it is feasible but rather fail than retry forever for all
> +	 * request sizes.
> +	 */
> +	if (flags & KM_MAYFAIL)
> +		lflags |= __GFP_RETRY_MAYFAIL;
> +
>  	if (flags & KM_ZERO)
>  		lflags |= __GFP_ZERO;
>  
> -- 
> 2.11.0
> 

-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2017-06-27  8:51 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-23  8:53 [PATCH 0/6] mm: give __GFP_REPEAT a better semantic Michal Hocko
2017-06-23  8:53 ` [PATCH 1/6] MIPS: do not use __GFP_REPEAT for order-0 request Michal Hocko
2017-06-23 10:27   ` Ralf Baechle
2017-06-26  9:36   ` Vlastimil Babka
2017-06-23  8:53 ` [PATCH 2/6] mm, tree wide: replace __GFP_REPEAT by __GFP_RETRY_MAYFAIL with more useful semantic Michal Hocko
2017-06-26 11:45   ` Vlastimil Babka
2017-06-26 12:14     ` Michal Hocko
2017-06-26 12:17       ` Vlastimil Babka
2017-06-26 12:38         ` Michal Hocko
2017-06-26 12:42           ` Michal Hocko
2017-06-26 11:53   ` Vlastimil Babka
2017-06-23  8:53 ` [PATCH 3/6] xfs: map KM_MAYFAIL to __GFP_RETRY_MAYFAIL Michal Hocko
2017-06-27  8:49   ` Michal Hocko [this message]
2017-06-27 13:47     ` Christoph Hellwig
2017-06-27 14:06       ` Michal Hocko
2017-06-28  4:12         ` Darrick J. Wong
2017-06-23  8:53 ` [PATCH 4/6] mm: kvmalloc support __GFP_RETRY_MAYFAIL for all sizes Michal Hocko
2017-06-26 12:00   ` Vlastimil Babka
2017-06-26 12:18     ` Michal Hocko
2017-06-23  8:53 ` [PATCH 5/6] drm/i915: use __GFP_RETRY_MAYFAIL Michal Hocko
2017-06-23  8:53 ` [PATCH 6/6] mm, migration: do not trigger OOM killer when migrating memory Michal Hocko
2017-06-23 20:43   ` Andrew Morton
2017-06-26  5:28     ` Michal Hocko
2017-06-26 12:13   ` Vlastimil Babka

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