From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 1CB586B01BF for ; Sat, 19 Jun 2010 09:30:08 -0400 (EDT) Date: Sat, 19 Jun 2010 15:30:00 +0200 From: Andi Kleen Subject: Re: [PATCH] [31/31] HWPOISON: Add a madvise() injector for soft page offlining Message-ID: <20100619133000.GL18946@basil.fritz.box> References: <200912081016.198135742@firstfloor.org> <20091208211647.9B032B151F@basil.firstfloor.org> <20100619132055.GK18946@basil.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org To: Michael Kerrisk Cc: Andi Kleen , fengguang.wu@intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 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 wrote: > >> > > >> > 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: Sat Jun 19 15:19:28 2010 +0200 > > > > MADV_SOFT_OFFLINE > > > > Signed-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. > > This operation may result in the calling process receiving a > > .B SIGBUS > > and 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 operation > > Can you explain the term "offlined" please. The memory is not used anymore and taken out of normal memory management (until unpoisoned) and the "HardwareCorrupted:" counter in /proc/meminfo increases (don't put the later in, I'm thinking about changing that) > > > +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. -Andi -- 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