linux-kernel - Re: [PATCH v4 4/5] cramfs: add mmap support

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: <nycvar.YSQ.7.76.1710021931270.5407@knanqh.ubzr>
Date:   Mon, 2 Oct 2017 19:33:29 -0400 (EDT)
From:   Nicolas Pitre <nicolas.pitre@...aro.org>
To:     Richard Weinberger <richard.weinberger@...il.com>
cc:     Christoph Hellwig <hch@...radead.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        "linux-embedded@...r.kernel.org" <linux-embedded@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Chris Brandt <Chris.Brandt@...esas.com>
Subject: Re: [PATCH v4 4/5] cramfs: add mmap support

On Tue, 3 Oct 2017, Richard Weinberger wrote:

> On Mon, Oct 2, 2017 at 12:29 AM, Nicolas Pitre <nicolas.pitre@...aro.org> wrote:
> > On Sun, 1 Oct 2017, Christoph Hellwig wrote:
> >
> >> up_read(&mm->mmap_sem) in the fault path is a still a complete
> >> no-go,
> >>
> >> NAK
> >
> > Care to elaborate?
> >
> > What about mm/filemap.c:__lock_page_or_retry() then?
> 
> As soon you up_read() in the page fault path other tasks will race
> with you before
> you're able to grab the write lock.

But I _know_ that.

Could you highlight an area in my code where this is not accounted for?


Nicolas