From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vc0-f170.google.com (mail-vc0-f170.google.com [209.85.220.170]) by kanga.kvack.org (Postfix) with ESMTP id 4FADA6B0038 for ; Sat, 27 Sep 2014 03:01:56 -0400 (EDT) Received: by mail-vc0-f170.google.com with SMTP id ij19so7897571vcb.1 for ; Sat, 27 Sep 2014 00:01:55 -0700 (PDT) Received: from mail-vc0-x234.google.com (mail-vc0-x234.google.com [2607:f8b0:400c:c03::234]) by mx.google.com with ESMTPS id w18si3266933vdj.103.2014.09.27.00.01.54 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 27 Sep 2014 00:01:54 -0700 (PDT) Received: by mail-vc0-f180.google.com with SMTP id hq12so2786553vcb.11 for ; Sat, 27 Sep 2014 00:01:54 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <542628C8.8030004@oracle.com> References: <5420407E.8040406@oracle.com> <542628C8.8030004@oracle.com> Date: Sat, 27 Sep 2014 11:01:54 +0400 Message-ID: Subject: Re: mm: NULL ptr deref in migrate_page_move_mapping From: Andrey Ryabinin Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Sasha Levin Cc: Hugh Dickins , "linux-mm@kvack.org" , Andrew Morton , Konstantin Khlebnikov , Johannes Weiner , Naoya Horiguchi , Mel Gorman , Andrey Ryabinin 2014-09-27 7:02 GMT+04:00 Sasha Levin : > On 09/22/2014 07:04 PM, Hugh Dickins wrote: >>> but I'm not sure what went wrong. >> Most likely would be a zeroing of the radix_tree node, just as you >> were experiencing zeroing of other mm structures in earlier weeks. >> >> Not that I've got any suggestions on where to take it from there. > > I've added poisoning to a few mm related structures, and managed to > confirm that the issue here is indeed corruption rather than something > specific with the given structures. > > Right now I'm looking into making KASan (Cc Andrey) to mark the poison > bytes somehow so it would trigger an error on access, that way we'll > know what's corruption them. > > Andrey, since it takes a while to trigger this corruption, could you > confirm that if I kasan_poison_shadow() a few bytes I will get a KASan > report on any read/write to them? > That's right. Note that poison value has to be negative. Address and size of poisoned area has to be aligned to 8 bytes. -- Best regards, Andrey Ryabinin -- 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