linux-kernel - Re: [PATCH] mm/hugetlb: Fix uffd wr-protection for CoW optimization path

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Message-ID: <ZBokogPMNsz+1Rsb@x1n>
Date:   Tue, 21 Mar 2023 17:41:54 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Mike Kravetz <mike.kravetz@...cle.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Nadav Amit <nadav.amit@...il.com>,
        David Hildenbrand <david@...hat.com>,
        Muhammad Usama Anjum <usama.anjum@...labora.com>,
        linux-stable <stable@...r.kernel.org>
Subject: Re: [PATCH] mm/hugetlb: Fix uffd wr-protection for CoW optimization
 path

On Tue, Mar 21, 2023 at 01:57:19PM -0700, Mike Kravetz wrote:
> > This patch fixes an issue that a hugetlb uffd-wr-protected mapping can be
> > writable even with uffd-wp bit set.  It only happens with all these
> > conditions met: (1) hugetlb memory (2) private mapping (3) original mapping
> > was missing, then (4) being wr-protected (IOW, pte marker installed).  Then
>                ^^^^
> Nit, but is the word "then" intended to be there?  Almost makes it sound as
> if wr-protected was a result of the previous 3 conditions being met.

Not intended..  Since this is not fixup-able, I'll reword here when I'll
need to repost.

[...]

> Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>

Thanks!

-- 
Peter Xu