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Date:   Sun, 21 Aug 2022 17:10:06 -0700
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Subject: Re: [syzbot] general protection fault in vma_is_shmem
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To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     syzbot <syzbot+681bbbb80445ead3c040@syzkaller.appspotmail.com>,
        hughd@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        syzkaller-bugs@googlegroups.com,
        Alistair Popple <apopple@nvidia.com>,
        David Hildenbrand <david@redhat.com>,
        Jason Gunthorpe <jgg@nvidia.com>
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 <20220821163120.df7d936c9f47b6dc875ab763@linux-foundation.org>
From:   John Hubbard <jhubbard@nvidia.com>
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On 8/21/22 16:31, Andrew Morton wrote:
> On Sun, 21 Aug 2022 16:18:48 -0700 John Hubbard <jhubbard@nvidia.com> wrote:
> 
>>> vmas[] array.  We haven't messed with gup.c much this time around -
>>> just one patch from Alistair ("mm/gup.c: simplify and fix
>>> check_and_migrate_movable_pages() return codes").  It does touch this
>>> area, but I can't immediately see how it could newly cause this.
>>>
>>
>> Neither can I, even after looking at both of these recent commits to
>> gup.c in this branch:
>>
>> commit 4d1225cd5560 ("mm/gup.c: simplify and fix
>> check_and_migrate_movable_pages() return codes")
>>
>> commit 0e5d6dac6b65 ("mm/gup: fix FOLL_FORCE COW security issue and
>> remove FOLL_COW")
>>
>> As you say, a bisection would really help here.
> 
> Might
> https://lkml.kernel.org/r/20220821183547.950370-1-syoshida@redhat.com
> save us?
> 
> 

aha yes, that looks right.


thanks,
-- 
John Hubbard
NVIDIA