Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934886AbdC3UU2 (ORCPT ); Thu, 30 Mar 2017 16:20:28 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:49837 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934658AbdC3UU1 (ORCPT ); Thu, 30 Mar 2017 16:20:27 -0400 Subject: Re: [PATCH RESEND] mm/hugetlb: Don't call region_abort if region_chg fails To: Dmitry Vyukov , Andrew Morton References: <1490821682-23228-1-git-send-email-mike.kravetz@oracle.com> <20170329141711.50c183a7bb1bfa75e24d4426@linux-foundation.org> Cc: "linux-mm@kvack.org" , LKML , Hillf Danton , Michal Hocko , "Kirill A . Shutemov" , Andrey Ryabinin , Naoya Horiguchi From: Mike Kravetz Message-ID: <66a8e9a2-b116-9d4c-fa74-138838a5b1d9@oracle.com> Date: Thu, 30 Mar 2017 13:20:12 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1036 Lines: 29 On 03/30/2017 05:28 AM, Dmitry Vyukov wrote: > On Wed, Mar 29, 2017 at 11:17 PM, Andrew Morton > wrote: >> On Wed, 29 Mar 2017 14:08:02 -0700 Mike Kravetz wrote: >> >>> >>> syzkaller fuzzer found this bug, that resulted in the following: >> >> I'll change the above to >> >> : syzkaller fuzzer (when using an injected kmalloc failure) found this bug, >> : that resulted in the following: >> >> it's important, because this bug won't be triggered (at all easily, at >> least) in real-world workloads. > > I wonder if memory-constrained cgroups make such bugs much easier to trigger. > I think you might expose some bugs with memory-constrained cgroups. However, it is unlikely you could trigger this bug using that method. In this bug the injected kmalloc failure was for a 32 byte allocation. My guess is that it would be very very unlikely/lucky to have the allocations done by other routines on the stack succeed, and have this 32 byte allocation fail. -- Mike Kravetz