linux-kernel - Re: [PATCH RFC v2 1/2] mm: Don't skip swap entry even if zap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Ye5ts7VtDnja2VUZ@xz-m1.local>
Date:   Mon, 24 Jan 2022 17:13:23 +0800
From:   Peter Xu <peterx@...hat.com>
To:     Hugh Dickins <hughd@...gle.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        David Hildenbrand <david@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Yang Shi <shy828301@...il.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alistair Popple <apopple@...dia.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH RFC v2 1/2] mm: Don't skip swap entry even if zap_details
 specified

On Sun, Jan 23, 2022 at 10:51:57PM -0800, Hugh Dickins wrote:
> I don't know of any problem that needs fixing with the zero page:
> how do you suppose the zero page gets into a truncatable or hole-punchable
> mapping?  We use it for read faults in anonymous mappings.  And I told the
> story of how once-upon-a-time it could get inserted into any mapping by
> reading from /dev/zero, but that odd case was dropped years ago.  And I
> am open to (even encouraging) a change to make use of zero page for read
> faults of holes in shmem: but that's potential future work, which would
> require some changes elsewhere (though perhaps none here: the zero page
> could never be used for the result of a COW).
> 
> Please explain the zero page problem you hope to fix here.

After I tried to learn the old/new worlds of zero page somehow I thought there
can be zero pfns installed, but it seems not at all..

Please ignore above, sorry for the noise.

-- 
Peter Xu