From mboxrd@z Thu Jan 1 00:00:00 1970 From: KOSAKI Motohiro Subject: Re: [Bisected Regression in 2.6.35] A full tmpfs filesystem causeshibernation to hang Date: Fri, 3 Sep 2010 10:53:32 +0900 (JST) Message-ID: <20100903105216.B65C.A69D9226__19506.3558327549$1283478886$gmane$org@jp.fujitsu.com> References: <20100903085756.B657.A69D9226@jp.fujitsu.com> <201009030307.34057.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201009030307.34057.rjw@sisk.pl> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: "Rafael J. Wysocki" Cc: linux-pm@lists.linux-foundation.org, "M. Vefa Bicakci" , Linux Kernel Mailing List , kosaki.motohiro@jp.fujitsu.com List-Id: linux-pm@vger.kernel.org > On Friday, September 03, 2010, KOSAKI Motohiro wrote: > > Hello, > > > > > > > > Like in the patch below, perhaps? > > > > > > > > > > Looks like fine. but I have one question. hibernate_preallocate_memory() call > > > > > preallocate_image_memory() two times. Why do you only care latter one? > > > > > former one seems similar risk. > > > > > > > > The first one is mandatory, ie. if we can't allocate the requested number of > > > > pages at this point, we fail the entire hibernation. In that case the > > > > performance hit doesn't matter. > > > > > > IOW, your patch at http://lkml.org/lkml/2010/9/2/262 is still necessary to > > > protect against the infinite loop in that case. > > > > As far as I understand, we need distinguish two allocation failure. > > 1) failure because no enough memory > > -> yes, hibernation should fail > > 2) failure because already allocated enough lower zone memory > > -> why should we fail? > > > > If the system has a lot of memory, scenario (2) is happen frequently than (1). > > I think we need check alloc_highmem and alloc_normal variable and call > > preallocate_image_highmem() again instead preallocate_image_memory() > > if we've alread allocated enough lots normal memory. > > > > nit? > > Actually I thought about that, but we don't really see hibernation fail for > this reason. In all of the tests I carried out the requested 50% of highmem > had been allocated before allocations from the normal zone started to be > made, even if highmem was 100% full at that point. So this appears to be > a theoretical issue and covering it would require us to change the algorithm > entirely (eg. it doesn't make sense to call preallocate_highmem_fraction() down > the road if that happens). ok, thanks. probably I've catched your point. please feel free to use my reviewed-by for your fix. thanks.