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Date: Fri, 28 Dec 2012 01:37:02 +0100 From: Sedat Dilek <sedat.dilek@...il.com> To: Zlatko Calusic <zlatko.calusic@...on.hr> Cc: LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org> Subject: Re: BUG: unable to handle kernel NULL pointer dereference at 0000000000000500 On Fri, Dec 28, 2012 at 1:33 AM, Zlatko Calusic <zlatko.calusic@...on.hr> wrote: > On 28.12.2012 01:24, Sedat Dilek wrote: >> >> On Fri, Dec 28, 2012 at 12:51 AM, Zlatko Calusic >> <zlatko.calusic@...on.hr> wrote: >>> >>> On 28.12.2012 00:42, Sedat Dilek wrote: >>>> >>>> >>>> On Fri, Dec 28, 2012 at 12:39 AM, Zlatko Calusic >>>> <zlatko.calusic@...on.hr> 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? - Sedat - > Thanks, > -- > Zlatko -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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