From: NeilBrown <neilb@suse.de>
To: Mel Gorman <mgorman@suse.de>
Cc: Linux-MM <linux-mm@kvack.org>,
Linux-Netdev <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
David Miller <davem@davemloft.net>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH 02/13] mm: sl[au]b: Add knowledge of PFMEMALLOC reserve pages
Date: Tue, 26 Apr 2011 21:15:00 +1000 [thread overview]
Message-ID: <20110426211500.02d6a5a6@notabene.brown> (raw)
In-Reply-To: <1303803414-5937-3-git-send-email-mgorman@suse.de>
On Tue, 26 Apr 2011 08:36:43 +0100 Mel Gorman <mgorman@suse.de> wrote:
> +bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
> +{
> + return gfp_to_alloc_flags(gfp_mask) & ALLOC_PFMEMALLOC;
> +}
> +
> static inline struct page *
> __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> struct zonelist *zonelist, enum zone_type high_zoneidx,
> @@ -2202,8 +2211,16 @@ nopage:
> got_pg:
> if (kmemcheck_enabled)
> kmemcheck_pagealloc_alloc(page, order, gfp_mask);
> - return page;
>
> + /*
> + * page->pfmemalloc is set when the caller had PFMEMALLOC set or is
> + * been OOM killed. The expectation is that the caller is taking
> + * steps that will free more memory. The caller should avoid the
> + * page being used for !PFMEMALLOC purposes.
> + */
> + page->pfmemalloc = (alloc_flags & ALLOC_PFMEMALLOC);
> +
> + return page;
Linus doesn't seem to be a fan of this construct:
https://lkml.org/lkml/2011/4/1/255
pfmemalloc is a bool, and the value on the right is either 0 or 0x1000.
If bool happens to be typedefed to 'char' or even 'short', pfmemalloc would
always be set to 0.
Ditto for the gfp_pfmemalloc_allowed function.
Prefixing with '!!' would make it safe.
NeilBrown
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next prev parent reply other threads:[~2011-04-26 11:15 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-26 7:36 [PATCH 00/13] Swap-over-NBD without deadlocking Mel Gorman
2011-04-26 7:36 ` [PATCH 01/13] mm: Serialize access to min_free_kbytes Mel Gorman
2011-04-26 7:36 ` [PATCH 02/13] mm: sl[au]b: Add knowledge of PFMEMALLOC reserve pages Mel Gorman
2011-04-26 11:15 ` NeilBrown [this message]
2011-04-26 11:33 ` Mel Gorman
2011-04-26 12:05 ` NeilBrown
2011-04-26 11:37 ` NeilBrown
2011-04-26 13:59 ` Mel Gorman
2011-04-27 23:21 ` NeilBrown
2011-04-28 9:46 ` Mel Gorman
2011-04-26 7:36 ` [PATCH 03/13] mm: Introduce __GFP_MEMALLOC to allow access to emergency reserves Mel Gorman
2011-04-26 9:49 ` NeilBrown
2011-04-26 10:36 ` Mel Gorman
2011-04-26 10:53 ` NeilBrown
2011-04-26 14:00 ` Mel Gorman
2011-04-26 7:36 ` [PATCH 04/13] mm: allow PF_MEMALLOC from softirq context Mel Gorman
2011-04-26 7:36 ` [PATCH 05/13] mm: Ignore mempolicies when using ALLOC_NO_WATERMARK Mel Gorman
2011-04-26 7:36 ` [PATCH 06/13] net: Introduce sk_allocation() to allow addition of GFP flags depending on the individual socket Mel Gorman
2011-04-26 7:36 ` [PATCH 07/13] netvm: Allow the use of __GFP_MEMALLOC by specific sockets Mel Gorman
2011-04-26 7:36 ` [PATCH 08/13] netvm: Allow skb allocation to use PFMEMALLOC reserves Mel Gorman
2011-04-26 7:36 ` [PATCH 09/13] netvm: Set PF_MEMALLOC as appropriate during SKB processing Mel Gorman
2011-04-26 12:21 ` NeilBrown
2011-04-26 14:10 ` Mel Gorman
2011-04-26 23:22 ` NeilBrown
2011-04-26 7:36 ` [PATCH 10/13] mm: Micro-optimise slab to avoid a function call Mel Gorman
2011-04-26 7:36 ` [PATCH 11/13] nbd: Set SOCK_MEMALLOC for access to PFMEMALLOC reserves Mel Gorman
2011-04-26 7:36 ` [PATCH 12/13] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage Mel Gorman
2011-04-26 12:30 ` NeilBrown
2011-04-26 14:26 ` Mel Gorman
2011-04-26 23:18 ` NeilBrown
2011-04-27 8:36 ` Mel Gorman
2011-04-26 7:36 ` [PATCH 13/13] mm: Account for the number of times direct reclaimers get throttled Mel Gorman
2011-04-26 12:35 ` NeilBrown
2011-04-26 14:26 ` Mel Gorman
2011-04-26 14:23 ` [PATCH 00/13] Swap-over-NBD without deadlocking Peter Zijlstra
2011-04-26 14:46 ` Mel Gorman
2011-04-26 14:50 ` Peter Zijlstra
2011-04-27 8:43 ` Mel Gorman
2011-04-28 13:31 ` Pavel Machek
2011-04-28 13:42 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2011-04-27 16:07 [PATCH 00/13] Swap-over-NBD without deadlocking v3 Mel Gorman
2011-04-27 16:08 ` [PATCH 02/13] mm: sl[au]b: Add knowledge of PFMEMALLOC reserve pages Mel Gorman
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