linux-kernel - Re: [PATCH 1/5] mm: Introduce mm_struct.has

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: <20200921223004.GB19098@xz-x1>
Date:   Mon, 21 Sep 2020 18:30:04 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Jann Horn <jannh@...gle.com>
Cc:     Linux-MM <linux-mm@...ck.org>,
        kernel list <linux-kernel@...r.kernel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>, Michal Hocko <mhocko@...e.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Kirill Shutemov <kirill@...temov.name>,
        Hugh Dickins <hughd@...gle.com>,
        Christoph Hellwig <hch@....de>,
        Andrea Arcangeli <aarcange@...hat.com>,
        John Hubbard <jhubbard@...dia.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Leon Romanovsky <leonro@...dia.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 1/5] mm: Introduce mm_struct.has_pinned

On Mon, Sep 21, 2020 at 11:43:38PM +0200, Jann Horn wrote:
> On Mon, Sep 21, 2020 at 11:17 PM Peter Xu <peterx@...hat.com> wrote:
> >
> > (Commit message collected from Jason Gunthorpe)
> >
> > Reduce the chance of false positive from page_maybe_dma_pinned() by keeping
> > track if the mm_struct has ever been used with pin_user_pages(). mm_structs
> > that have never been passed to pin_user_pages() cannot have a positive
> > page_maybe_dma_pinned() by definition.
> 
> There are some caveats here, right? E.g. this isn't necessarily true
> for pagecache pages, I think?

Sorry I didn't follow here.  Could you help explain with some details?

Thanks,

-- 
Peter Xu