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Date:   Sun, 21 Aug 2022 16:31:20 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     John Hubbard <jhubbard@nvidia.com>
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>
Subject: Re: [syzbot] general protection fault in vma_is_shmem
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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?