linux-kernel - Re: [GIT PULL v2] Early SLAB fixes for 2.6.31

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Date:	Fri, 12 Jun 2009 13:30:33 -0400 (EDT)
From:	Christoph Lameter <cl@...ux-foundation.org>
To:	Pekka J Enberg <penberg@...helsinki.fi>
cc:	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, kamezawa.hiroyu@...fujitsu.com,
	lizf@...fujitsu.com, mingo@...e.hu, npiggin@...e.de,
	yinghai@...nel.org, benh@...nel.crashing.org
Subject: Re: [GIT PULL v2] Early SLAB fixes for 2.6.31

On Fri, 12 Jun 2009, Pekka J Enberg wrote:

> @@ -3434,6 +3451,8 @@ __cache_alloc(struct kmem_cache *cachep, gfp_t flags, void *caller)
>  	unsigned long save_flags;
>  	void *objp;
>
> +	flags &= slab_gfp_mask;
> +
>  	lockdep_trace_alloc(flags);
>
>  	if (slab_should_failslab(cachep, flags))

Adds code to hot code path.

> @@ -1595,6 +1601,8 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
>  	unsigned long flags;
>  	unsigned int objsize;
>
> +	gfpflags &= slab_gfp_mask;
> +
>  	lockdep_trace_alloc(gfpflags);
>  	might_sleep_if(gfpflags & __GFP_WAIT);
>

Adds code to hot code path.

The allocators mask flags passed to the page allocator through
GFP_RECLAIM_MASK|GFP_CONSTRAINT_MASK. This is done outside of the critical
code paths.

The might_sleep issues may be fixed by adding another check to
__might_sleep().


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