From: Joel Fernandes <joel@joelfernandes.org>
To: Brian Geffon <bgeffon@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Michael S . Tsirkin" <mst@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Sonny Rao <sonnyrao@google.com>,
Minchan Kim <minchan@kernel.org>,
"Kirill A . Shutemov" <kirill@shutemov.name>
Subject: Re: [PATCH] userfaultfd: fix remap event with MREMAP_DONTUNMAP.
Date: Wed, 6 May 2020 21:35:10 -0400 [thread overview]
Message-ID: <CAEXW_YT34g6aypdia0AsXGQ1MxGtD9=DF=mpAwKWaLM6JuSpcQ@mail.gmail.com> (raw)
In-Reply-To: <CADyq12wW-j9vi0oxXB_+sjSyP=FgaNWkRM2Yo9YqkEwGnOb0bA@mail.gmail.com>
On Wed, May 6, 2020 at 9:11 PM Brian Geffon <bgeffon@google.com> wrote:
>
> > > - mremap_userfaultfd_complete(&uf, addr, new_addr, old_len);
> > > + mremap_userfaultfd_complete(&uf, addr, ret, old_len);
> >
> > Not super familiar with this code, but thought I'd ask, does ret
> > to be checked for -ENOMEM before calling mremap_userfaultfd_complete?
> > Sorry if I missed something.
>
> No, mremap_userfaultfd_complete will do a check similar to
> offset_in_page() by checking the page mask.
> It does (to & ~PAGE_MASK) to check for a non-aligned "to" value, so we're good.
>
> Additionally, earlier in the process then ctx will be null because we
> will have never called mremap_userfaultfd_prep,
> and mremap_userfaultfd_complete will check if there is a context
> before proceeding.
Makes sense.
thanks,
- Joel
prev parent reply other threads:[~2020-05-07 1:35 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-06 17:21 [PATCH] userfaultfd: fix remap event with MREMAP_DONTUNMAP Brian Geffon
2020-05-06 17:28 ` Joel Fernandes
2020-05-06 17:32 ` Brian Geffon
2020-05-07 0:55 ` Joel Fernandes
2020-05-07 1:06 ` Joel Fernandes
2020-05-07 1:11 ` Brian Geffon
2020-05-07 1:35 ` Joel Fernandes [this message]
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