From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Hugh Dickins <hughd@google.com>,
Yury Gribov <y.gribov@samsung.com>,
Alexandr Andreev <aandreev@parallels.com>,
Vassili Karpov <av1474@comtv.ru>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH RFC] drivers/char/mem: byte generating devices and poisoned mappings
Date: Tue, 1 Apr 2014 19:07:38 +0300 [thread overview]
Message-ID: <20140401160738.GA15175@node.dhcp.inet.fi> (raw)
In-Reply-To: <CALYGNiPvZSg7_b47+TbjhTzt0vBSRiXN8edVH=9A3YJOMQMqjA@mail.gmail.com>
On Tue, Apr 01, 2014 at 07:15:31PM +0400, Konstantin Khlebnikov wrote:
> On Tue, Apr 1, 2014 at 2:36 PM, Kirill A. Shutemov <kirill@shutemov.name> wrote:
> > On Tue, Apr 01, 2014 at 01:16:07AM +0400, Konstantin Khlebnikov wrote:
> >> This patch adds 256 virtual character devices: /dev/byte0, ..., /dev/byte255.
> >> Each works like /dev/zero but generates memory filled with particular byte.
> >
> > Shouldn't /dev/byte0 be an alias for /dev/zero?
> > I see you reuse ZERO_PAGE(0) for that, but what about all these special
> > cases /dev/zero has?
>
> What special cases? I found rss-accounting part, you've mentioned coredump.
I'm not sure what else is there. It's probably good idea to check all
users of vm_normal_page().
One thing is zero page coloring which some archs have.
--
Kirill A. Shutemov
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WARNING: multiple messages have this Message-ID (diff)
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Hugh Dickins <hughd@google.com>,
Yury Gribov <y.gribov@samsung.com>,
Alexandr Andreev <aandreev@parallels.com>,
Vassili Karpov <av1474@comtv.ru>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH RFC] drivers/char/mem: byte generating devices and poisoned mappings
Date: Tue, 1 Apr 2014 19:07:38 +0300 [thread overview]
Message-ID: <20140401160738.GA15175@node.dhcp.inet.fi> (raw)
In-Reply-To: <CALYGNiPvZSg7_b47+TbjhTzt0vBSRiXN8edVH=9A3YJOMQMqjA@mail.gmail.com>
On Tue, Apr 01, 2014 at 07:15:31PM +0400, Konstantin Khlebnikov wrote:
> On Tue, Apr 1, 2014 at 2:36 PM, Kirill A. Shutemov <kirill@shutemov.name> wrote:
> > On Tue, Apr 01, 2014 at 01:16:07AM +0400, Konstantin Khlebnikov wrote:
> >> This patch adds 256 virtual character devices: /dev/byte0, ..., /dev/byte255.
> >> Each works like /dev/zero but generates memory filled with particular byte.
> >
> > Shouldn't /dev/byte0 be an alias for /dev/zero?
> > I see you reuse ZERO_PAGE(0) for that, but what about all these special
> > cases /dev/zero has?
>
> What special cases? I found rss-accounting part, you've mentioned coredump.
I'm not sure what else is there. It's probably good idea to check all
users of vm_normal_page().
One thing is zero page coloring which some archs have.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2014-04-01 16:08 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-31 21:16 [PATCH RFC] drivers/char/mem: byte generating devices and poisoned mappings Konstantin Khlebnikov
2014-03-31 21:16 ` Konstantin Khlebnikov
2014-04-01 10:36 ` Kirill A. Shutemov
2014-04-01 10:36 ` Kirill A. Shutemov
2014-04-01 15:15 ` Konstantin Khlebnikov
2014-04-01 15:15 ` Konstantin Khlebnikov
2014-04-01 16:07 ` Kirill A. Shutemov [this message]
2014-04-01 16:07 ` Kirill A. Shutemov
2014-04-01 16:59 ` One Thousand Gnomes
2014-04-01 16:59 ` One Thousand Gnomes
2014-04-01 17:27 ` Konstantin Khlebnikov
2014-04-01 17:27 ` Konstantin Khlebnikov
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