From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx128.postini.com [74.125.245.128]) by kanga.kvack.org (Postfix) with SMTP id 4D0786B004D for ; Tue, 15 May 2012 06:08:34 -0400 (EDT) Date: Tue, 15 May 2012 11:08:29 +0100 From: Mel Gorman Subject: Re: [PATCH 01/12] netvm: Prevent a stream-specific deadlock Message-ID: <20120515100829.GH29102@suse.de> References: <1336658065-24851-2-git-send-email-mgorman@suse.de> <20120511.011034.557833140906762226.davem@davemloft.net> <20120514105604.GB29102@suse.de> <20120514.162634.1094732813264319951.davem@davemloft.net> <20120515091402.GG29102@suse.de> <1337075234.27694.9.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1337075234.27694.9.camel@twins> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: David Miller , akpm@linux-foundation.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Trond.Myklebust@netapp.com, neilb@suse.de, hch@infradead.org, michaelc@cs.wisc.edu, emunson@mgebm.net On Tue, May 15, 2012 at 11:47:14AM +0200, Peter Zijlstra wrote: > On Tue, 2012-05-15 at 10:14 +0100, Mel Gorman wrote: > > @@ -289,6 +289,18 @@ void sk_clear_memalloc(struct sock *sk) > > sock_reset_flag(sk, SOCK_MEMALLOC); > > sk->sk_allocation &= ~__GFP_MEMALLOC; > > static_key_slow_dec(&memalloc_socks); > > + > > + /* > > + * SOCK_MEMALLOC is allowed to ignore rmem limits to ensure forward > > + * progress of swapping. However, if SOCK_MEMALLOC is cleared while > > + * it has rmem allocations there is a risk that the user of the > > + * socket cannot make forward progress due to exceeding the rmem > > + * limits. By rights, sk_clear_memalloc() should only be called > > + * on sockets being torn down but warn and reset the accounting if > > + * that assumption breaks. > > + */ > > + if (WARN_ON(sk->sk_forward_alloc)) > > WARN_ON_ONCE() perhaps? > I do not expect SOCK_MEMALLOC to be cleared frequently at all with the possible exception of swapon/swapoff stress tests. If the flag is being cleared regularly with rmem tokens then that is interesting in itself but a WARN_ON_ONCE would miss it. > > + sk_mem_reclaim(sk); > > } -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org