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 03/13] mm: Introduce __GFP_MEMALLOC to allow access to emergency reserves
Date: Tue, 26 Apr 2011 20:53:30 +1000 [thread overview]
Message-ID: <20110426205330.539a2766@notabene.brown> (raw)
In-Reply-To: <20110426103646.GD4658@suse.de>
On Tue, 26 Apr 2011 11:36:46 +0100 Mel Gorman <mgorman@suse.de> wrote:
> On Tue, Apr 26, 2011 at 07:49:47PM +1000, NeilBrown wrote:
> > Maybe a
> > WARN_ON((gfp_mask & __GFP_MEMALLOC) && (gfp_mask & __GFP_NOMEMALLOC));
> > might be wise?
> >
>
> Both MEMALLOC and NOMEMALLOC are related to PFMEMALLOC reserves so
> it's reasonable for them to have similar names. This warning will
> also trigger because it's a combination of flags that does happen.
>
> Consider for example
>
> any interrupt
> -> __netdev_alloc_skb (mask == GFP_ATOMIC)
> -> __alloc_skb (mask == GFP_ATOMIC)
> if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
> gfp_mask |= __GFP_MEMALLOC;
> (mask == GFP_ATOMIC|__GFP_NOMEMALLOC)
> -> __kmalloc_reserve
> First attempt tries to avoid reserves so adds __GFP_MEMALLOC
> (mask == GFP_ATOMIC|__GFP_NOMEMALLOC|__GFP_MEMALLOC)
>
You have the "NO"s mixed up a bit which confused me for a while :-)
But I see your point - I guess the WARN_ON isn't really needed.
> You're right in that __GFP_NOMEMALLOC overrides __GFP_MEMALLOC so that
> could do with a note.
>
Thanks,
NeilBrown
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next prev parent reply other threads:[~2011-04-26 10:53 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
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 [this message]
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 03/13] mm: Introduce __GFP_MEMALLOC to allow access to emergency reserves Mel Gorman
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