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From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Arjan van de Ven <arjan@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	netdev@vger.kernel.org,
	Trond Myklebust <trond.myklebust@fys.uio.no>,
	Thomas Graf <tgraf@suug.ch>, David Miller <davem@davemloft.net>
Subject: Re: [PATCH 03/29] mm: allow PF_MEMALLOC from softirq context
Date: Thu, 22 Feb 2007 10:16:23 +0100	[thread overview]
Message-ID: <1172135783.6374.30.camel@twins> (raw)
In-Reply-To: <1172073217.3531.200.camel@laptopd505.fenrus.org>

On Wed, 2007-02-21 at 16:53 +0100, Arjan van de Ven wrote:
> > Index: linux-2.6-git/kernel/softirq.c
> > ===================================================================
> > --- linux-2.6-git.orig/kernel/softirq.c	2006-12-14 10:02:18.000000000 +0100
> > +++ linux-2.6-git/kernel/softirq.c	2006-12-14 10:02:52.000000000 +0100
> > @@ -209,6 +209,8 @@ asmlinkage void __do_softirq(void)
> >  	__u32 pending;
> >  	int max_restart = MAX_SOFTIRQ_RESTART;
> >  	int cpu;
> > +	unsigned long pflags = current->flags;
> > +	current->flags &= ~PF_MEMALLOC;
> >  
> >  	pending = local_softirq_pending();
> >  	account_system_vtime(current);
> > @@ -247,6 +249,7 @@ restart:
> >  
> >  	account_system_vtime(current);
> >  	_local_bh_enable();
> > +	current->flags = pflags;
> 
> this wipes out all the flags in one go.... evil.
> What if something just selected this process for OOM killing? you nuke
> that flag here again. Would be nicer if only the PF_MEMALLOC bit got
> inherited in the restore path..

would something like this:

#define PF_PUSH(tsk, pflags, mask)		\
do {						\
	(pflags) = ((tsk)->flags) & (mask);	\
} while (0)


#define PF_POP(tsk, pflags, mask)		\
do {						\
	((tsk)->flags &= ~(mask);		\
	((tsk)->flags |= (pflags);		\
} while (0)

be useful, or shall I just open code it in various places?

(I made this same mistake; ignorant of the problem; all over this patch series)


  reply	other threads:[~2007-02-22  9:21 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-21 14:43 [PATCH 00/29] swap over networked storage -v11 Peter Zijlstra
2007-02-21 14:43 ` [PATCH 01/29] mm: page allocation rank Peter Zijlstra
2007-02-21 14:43 ` [PATCH 02/29] mm: slab allocation fairness Peter Zijlstra
2007-02-21 15:33   ` Pekka Enberg
2007-02-21 14:43 ` [PATCH 03/29] mm: allow PF_MEMALLOC from softirq context Peter Zijlstra
2007-02-21 15:53   ` Arjan van de Ven
2007-02-22  9:16     ` Peter Zijlstra [this message]
2007-02-22  9:48       ` Arjan van de Ven
2007-02-21 14:43 ` [PATCH 04/29] mm: serialize access to min_free_kbytes Peter Zijlstra
2007-02-21 14:43 ` [PATCH 05/29] mm: emergency pool Peter Zijlstra
2007-02-21 14:43 ` [PATCH 06/29] mm: __GFP_EMERGENCY Peter Zijlstra
2007-02-21 14:43 ` [PATCH 07/29] mm: allow mempool to fall back to memalloc reserves Peter Zijlstra
2007-02-21 14:43 ` [PATCH 08/29] mm: kmem_cache_objs_to_pages() Peter Zijlstra
2007-02-21 15:47   ` Pekka Enberg
2007-02-22  9:28     ` Peter Zijlstra
2007-02-22  9:45       ` Pekka Enberg
2007-02-22  9:49         ` Pekka Enberg
2007-02-21 14:43 ` [PATCH 09/29] selinux: tag avc cache alloc as non-critical Peter Zijlstra
2007-02-21 15:22   ` James Morris
2007-02-21 14:43 ` [PATCH 10/29] net: wrap sk->sk_backlog_rcv() Peter Zijlstra
2007-02-21 14:43 ` [PATCH 11/29] net: packet split receive api Peter Zijlstra
2007-02-21 14:43 ` [PATCH 12/29] net: remove alloc_skb_from_cache Peter Zijlstra
2007-02-21 14:43 ` [PATCH 13/29] netvm: link network to vm layer Peter Zijlstra
2007-02-21 14:43 ` [PATCH 14/29] netvm: INET reserves Peter Zijlstra
2007-02-21 14:43 ` [PATCH 15/29] netvm: hook skb allocation to reserves Peter Zijlstra
2007-02-21 14:43 ` [PATCH 16/29] netvm: filter emergency skbs Peter Zijlstra
2007-02-21 14:43 ` [PATCH 17/29] netvm: prevent a TCP specific deadlock Peter Zijlstra
2007-02-21 14:43 ` [PATCH 18/29] netfilter: notify about NF_QUEUE vs emergency skbs Peter Zijlstra
2007-02-24 15:27   ` Patrick McHardy
2007-02-24 15:46     ` Peter Zijlstra
2007-02-24 16:17       ` Patrick McHardy
2007-02-24 16:18         ` Peter Zijlstra
2007-02-24 16:40           ` Patrick McHardy
2007-02-24 16:55             ` Peter Zijlstra
2007-02-21 14:43 ` [PATCH 19/29] netvm: skb processing Peter Zijlstra
2007-02-21 14:43 ` [PATCH 20/29] uml: rename arch/um remove_mapping() Peter Zijlstra
2007-02-21 14:43 ` [PATCH 21/29] mm: prepare swap entry methods for use in page methods Peter Zijlstra
2007-02-21 14:43 ` [PATCH 22/29] mm: add support for non block device backed swap files Peter Zijlstra
2007-02-21 14:43 ` [PATCH 23/29] mm: methods for teaching filesystems about PG_swapcache pages Peter Zijlstra
2007-02-21 14:43 ` [PATCH 24/29] nfs: remove mempools Peter Zijlstra
2007-02-21 14:43 ` [PATCH 25/29] nfs: only use stable storage for swap Peter Zijlstra
2007-02-21 14:43 ` [PATCH 26/29] nfs: teach the NFS client how to treat PG_swapcache pages Peter Zijlstra
2007-02-21 14:43 ` [PATCH 27/29] nfs: disable data cache revalidation for swapfiles Peter Zijlstra
2007-02-21 14:43 ` [PATCH 28/29] nfs: enable swap on NFS Peter Zijlstra
2007-02-21 14:43 ` [PATCH 29/29] balance_dirty_pages() vs throttle_vm_writeout() deadlock Peter Zijlstra

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