From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx166.postini.com [74.125.245.166]) by kanga.kvack.org (Postfix) with SMTP id C3B3C6B005D for ; Wed, 9 Jan 2013 08:42:52 -0500 (EST) Date: Wed, 9 Jan 2013 13:42:48 +0000 From: Mel Gorman Subject: Re: ppoll() stuck on POLLIN while TCP peer is sending Message-ID: <20130109134248.GE13304@suse.de> References: <20121228014503.GA5017@dcvr.yhbt.net> <20130102200848.GA4500@dcvr.yhbt.net> <20130104160148.GB3885@suse.de> <20130106120700.GA24671@dcvr.yhbt.net> <20130107122516.GC3885@suse.de> <20130107223850.GA21311@dcvr.yhbt.net> <20130108224313.GA13304@suse.de> <20130108232325.GA5948@dcvr.yhbt.net> <1357697647.18156.1217.camel@edumazet-glaptop> <1357698749.27446.6.camel@edumazet-glaptop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1357698749.27446.6.camel@edumazet-glaptop> Sender: owner-linux-mm@kvack.org List-ID: To: Eric Dumazet Cc: Eric Wong , linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Rik van Riel , Minchan Kim , Andrew Morton , Linus Torvalds On Tue, Jan 08, 2013 at 06:32:29PM -0800, Eric Dumazet wrote: > On Tue, 2013-01-08 at 18:14 -0800, Eric Dumazet wrote: > > On Tue, 2013-01-08 at 23:23 +0000, Eric Wong wrote: > > > Mel Gorman wrote: > > > > Please try the following patch. However, even if it works the benefit of > > > > capture may be so marginal that partially reverting it and simplifying > > > > compaction.c is the better decision. > > > > > > I already got my VM stuck on this one. I had two twosleepy instances, > > > 2774 was the one that got stuck (also confirmed by watching top). > > > > > > Btw, have you been able to reproduce this on your end? > > > > > > I think the easiest reproduction on my 2-core VM is by running 2 > > > twosleepy processes and doing the following to dirty a lot of pages: > > > > Given the persistent sk_stream_wait_memory() traces I suspect a plain > > TCP bug, triggered by some extra wait somewhere. > > > > Please mm guys don't spend too much time right now, I'll try to > > reproduce the problem. > > > > Don't be confused by sk_stream_wait_memory() name. > > A thread is stuck here because TCP stack is failing to wake it. > > > > Hmm, it seems sk_filter() can return -ENOMEM because skb has the > pfmemalloc() set. > The skb should not have pfmemalloc set in most cases, particularly after cfd19c5a (mm: only set page->pfmemalloc when ALLOC_NO_WATERMARKS was used) but the capture patch also failed to clear pfmemalloc properly so it could be set in error. -- 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/ . Don't email: email@kvack.org