From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 13DA96B01C1 for ; Sat, 19 Jun 2010 09:43:51 -0400 (EDT) Received: by ey-out-1920.google.com with SMTP id 13so156174eye.18 for ; Sat, 19 Jun 2010 06:43:49 -0700 (PDT) MIME-Version: 1.0 Reply-To: mtk.manpages@gmail.com In-Reply-To: <20100619133000.GL18946@basil.fritz.box> References: <200912081016.198135742@firstfloor.org> <20091208211647.9B032B151F@basil.firstfloor.org> <20100619132055.GK18946@basil.fritz.box> <20100619133000.GL18946@basil.fritz.box> From: Michael Kerrisk Date: Sat, 19 Jun 2010 15:43:28 +0200 Message-ID: Subject: Re: [PATCH] [31/31] HWPOISON: Add a madvise() injector for soft page offlining Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Andi Kleen Cc: fengguang.wu@intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Hi Andi, On Sat, Jun 19, 2010 at 3:30 PM, Andi Kleen wrote: > On Sat, Jun 19, 2010 at 03:25:16PM +0200, Michael Kerrisk wrote: >> Hi Andi, >> >> Thanks for this. Some comments below. >> >> On Sat, Jun 19, 2010 at 3:20 PM, Andi Kleen wrote: >> > On Sat, Jun 19, 2010 at 02:36:28PM +0200, Michael Kerrisk wrote: >> >> Hi Andi, >> >> >> >> On Tue, Dec 8, 2009 at 11:16 PM, Andi Kleen wro= te: >> >> > >> >> > Process based injection is much easier to handle for test programs, >> >> > who can first bring a page into a specific state and then test. >> >> > So add a new MADV_SOFT_OFFLINE to soft offline a page, similar >> >> > to the existing hard offline injector. >> >> >> >> I see that this made its way into 2.6.33. Could you write a short >> >> piece on it for the madvise.2 man page? >> > >> > Also fixed the previous snippet slightly. >> >> (thanks) >> >> > commit edb43354f0ffc04bf4f23f01261f9ea9f43e0d3d >> > Author: Andi Kleen >> > Date: =A0 Sat Jun 19 15:19:28 2010 +0200 >> > >> > =A0 =A0MADV_SOFT_OFFLINE >> > >> > =A0 =A0Signed-off-by: Andi Kleen >> > >> > diff --git a/man2/madvise.2 b/man2/madvise.2 >> > index db29feb..9dccd97 100644 >> > --- a/man2/madvise.2 >> > +++ b/man2/madvise.2 >> > @@ -154,7 +154,15 @@ processes. >> > =A0This operation may result in the calling process receiving a >> > =A0.B SIGBUS >> > =A0and the page being unmapped. >> > -This feature is intended for memory testing. >> > +This feature is intended for testing of memory error handling code. >> > +This feature is only available if the kernel was configured with >> > +.BR CONFIG_MEMORY_FAILURE . >> > +.TP >> > +.BR MADV_SOFT_OFFLINE " (Since Linux 2.6.33) >> > +Soft offline a page. This will result in the memory of the page >> > +being copied to a new page and original page be offlined. The operati= on >> >> Can you explain the term "offlined" please. > > The memory is not used anymore and taken out of normal > memory management (until unpoisoned) Is there a userspace operation to unpoison (i.e., reverse MADV_SOFT_OFFLINE= )? I ask because I wondered if there is something additional to be documented. > and the "HardwareCorrupted:" counter in /proc/meminfo increases > > (don't put the later in, I'm thinking about changing that) Okay. >> >> > +should be transparent to the calling process. >> >> Does "should be transparent" mean "is normally invisible"? > > Yes. It's similar to being swapped out and swapped in again. Okay. Thanks, Michael --=20 Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface" http://blog.man7.org/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org