From: Peter Xu <peterx@redhat.com>
To: Nadav Amit <nadav.amit@gmail.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Axel Rasmussen <axelrasmussen@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Ives van Hoorne <ives@codesandbox.io>
Subject: Re: [PATCH 2/2] mm/uffd: Sanity check write bit for uffd-wp protected ptes
Date: Thu, 10 Nov 2022 15:28:30 -0500 [thread overview]
Message-ID: <Y21e7vvP54JrtkAp@x1n> (raw)
In-Reply-To: <58FFF1A3-DC37-4D9F-ABF0-3C5DA519BFFB@gmail.com>
On Thu, Nov 10, 2022 at 10:43:25AM -0800, Nadav Amit wrote:
> On Nov 10, 2022, at 7:17 AM, Peter Xu <peterx@redhat.com> wrote:
>
> > +#ifdef CONFIG_DEBUG_VM
> > + /*
> > + * Having write bit for wr-protect-marked present ptes is fatal,
> > + * because it means the uffd-wp bit will be ignored and write will
> > + * just go through.
> > + *
> > + * Use any chance of pgtable walking to verify this (e.g., when
> > + * page swapped out or being migrated for all purposes). It means
> > + * something is already wrong. Tell the admin even before the
> > + * process crashes. We also nail it with wrong pgtable setup.
> > + */
> > + WARN_ON_ONCE(wp && pte_write(pte));
>
> How about VM_WARN_ON_ONCE() and no ifdef?
Oops.. Will quickly respin, thanks.
--
Peter Xu
prev parent reply other threads:[~2022-11-10 20:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-10 15:17 [PATCH 0/2] mm/migrate: Fix writable pte for read migration entry Peter Xu
2022-11-10 15:17 ` [PATCH 1/2] mm/migrate: Fix read-only page got writable when recover pte Peter Xu
2022-11-10 15:17 ` [PATCH 2/2] mm/uffd: Sanity check write bit for uffd-wp protected ptes Peter Xu
2022-11-10 18:43 ` Nadav Amit
2022-11-10 20:28 ` Peter Xu [this message]
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