From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx173.postini.com [74.125.245.173]) by kanga.kvack.org (Postfix) with SMTP id 500488D0001 for ; Thu, 27 Dec 2012 19:56:09 -0500 (EST) Received: by mail-qa0-f44.google.com with SMTP id z4so9441895qan.3 for ; Thu, 27 Dec 2012 16:56:08 -0800 (PST) MIME-Version: 1.0 Reply-To: sedat.dilek@gmail.com In-Reply-To: <50DCEB01.3060903@iskon.hr> References: <50DCDC21.6080303@iskon.hr> <50DCDEE5.9000700@iskon.hr> <50DCE8C8.8050103@iskon.hr> <50DCEB01.3060903@iskon.hr> Date: Fri, 28 Dec 2012 01:56:08 +0100 Message-ID: Subject: Re: BUG: unable to handle kernel NULL pointer dereference at 0000000000000500 From: Sedat Dilek Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Zlatko Calusic Cc: LKML , linux-mm On Fri, Dec 28, 2012 at 1:42 AM, Zlatko Calusic wrote: > On 28.12.2012 01:37, Sedat Dilek wrote: >> >> On Fri, Dec 28, 2012 at 1:33 AM, Zlatko Calusic >> wrote: >>> >>> On 28.12.2012 01:24, Sedat Dilek wrote: >>>> >>>> >>>> On Fri, Dec 28, 2012 at 12:51 AM, Zlatko Calusic >>>> wrote: >>>>> >>>>> >>>>> On 28.12.2012 00:42, Sedat Dilek wrote: >>>>>> >>>>>> >>>>>> >>>>>> On Fri, Dec 28, 2012 at 12:39 AM, Zlatko Calusic >>>>>> wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On 28.12.2012 00:30, Sedat Dilek wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Hi Zlatko, >>>>>>>> >>>>>>>> I am not sure if I hit the same problem as described in this thread. >>>>>>>> >>>>>>>> Under heavy load, while building a customized toolchain for the >>>>>>>> Freetz >>>>>>>> router project I got a BUG || NULL pointer derefence || kswapd || >>>>>>>> zone_balanced || pgdat_balanced() etc. (details see my screenshot). >>>>>>>> >>>>>>>> I will try your patch from [1] ***only*** on top of my last >>>>>>>> Linux-v3.8-rc1 GIT setup (post-v3.8-rc1 mainline + some net-fixes). >>>>>>>> >>>>>>> >>>>>>> Yes, that's the same bug. It should be fixed with my latest patch, so >>>>>>> I'd >>>>>>> appreciate you testing it, to be on the safe side this time. There >>>>>>> should >>>>>>> be >>>>>>> no difference if you apply it to anything newer than 3.8-rc1, so go >>>>>>> for >>>>>>> it. >>>>>>> Thanks! >>>>>>> >>>>>> >>>>>> Not sure how I can really reproduce this bug as one build worked fine >>>>>> within my last v3.8-rc1 kernel. >>>>>> I increased the parallel-make-jobs-number from "4" to "8" to stress a >>>>>> bit harder. >>>>>> Just building right now... and will report. >>>>>> >>>>>> If you have any test-case (script or whatever), please let me/us know. >>>>>> >>>>> >>>>> Unfortunately not, I haven't reproduced it yet on my machines. But it >>>>> seems >>>>> that bug will hit only under heavy memory pressure. When close to OOM, >>>>> or >>>>> possibly with lots of writing to disk. It's also possible that >>>>> fragmentation >>>>> of memory zones could provoke it, that means testing it for a longer >>>>> time. >>>>> >>>> >>>> I tested successfully by doing simultaneously... >>>> - building Freetz with 8 parallel make-jobs >>>> - building Linux GIT with 1 make-job >>>> - 9 tabs open in firefox >>>> - In one tab I ran YouTube music video >>>> - etc. >>>> >>>> I am reading [1] and [2] where another user reports success by reverting >>>> this... >>>> >>>> commit cda73a10eb3f493871ed39f468db50a65ebeddce >>>> "mm: do not sleep in balance_pgdat if there's no i/o congestion" >>>> >>>> BTW, this machine has also 4GiB RAM (Ubuntu/precise AMD64). >>>> >>>> Feel free to add a "Reported-by/Tested-by" if you think this is a >>>> positive report. >>>> >>> >>> Thanks for the testing! And keep running it in case something interesting >>> pops up. ;) >>> >>> No need to revert cda73a10eb because it fixes another bug. And the patch >>> you're now running fixes the new bug I introduced with a combination of >>> my >>> latest 2 patches. Nah, it gets complicated... :) >>> >>> But, at least I found the culprit and as soon as Linus applies the fix, >>> everything will be hunky dory again, at least on this front. :P >>> >> >> I am not subscribed to LKML and linux-mm,,, >> Do you have a patch with a proper subject and descriptive text? URL? >> > > Soon to follow. I'd appreciate Zhouping Liu testing it too, though. I understand, but I want to push your patch with a proper subject-line as a pending patch with reference to patchwork, so... - Sedat - > -- > Zlatko -- 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