From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx196.postini.com [74.125.245.196]) by kanga.kvack.org (Postfix) with SMTP id D73A76B005D for ; Tue, 8 Jan 2013 21:14:10 -0500 (EST) Received: by mail-pa0-f42.google.com with SMTP id rl6so707249pac.1 for ; Tue, 08 Jan 2013 18:14:10 -0800 (PST) Subject: Re: ppoll() stuck on POLLIN while TCP peer is sending From: Eric Dumazet In-Reply-To: <20130108232325.GA5948@dcvr.yhbt.net> 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> Content-Type: text/plain; charset="UTF-8" Date: Tue, 08 Jan 2013 18:14:07 -0800 Message-ID: <1357697647.18156.1217.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Eric Wong Cc: Mel Gorman , linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Rik van Riel , Minchan Kim , Andrew Morton , Linus Torvalds 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. -- 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