From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id C75256B005D for ; Mon, 28 Sep 2009 11:17:45 -0400 (EDT) Date: Mon, 28 Sep 2009 06:11:08 +0200 From: Andi Kleen Subject: Re: [RFC][PATCH] HWPOISON: remove the unsafe __set_page_locked() Message-ID: <20090928041108.GD1656@one.firstfloor.org> References: <20090926031537.GA10176@localhost> <20090926190645.GB14368@wotan.suse.de> <20090926213204.GX30185@one.firstfloor.org> <20090927192251.GB6327@wotan.suse.de> <20090927230118.GH6327@wotan.suse.de> <20090928011943.GB1656@one.firstfloor.org> <20090928025741.GI6327@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090928025741.GI6327@wotan.suse.de> Sender: owner-linux-mm@kvack.org To: Nick Piggin Cc: Andi Kleen , Hugh Dickins , Wu Fengguang , Andrew Morton , linux-mm@kvack.org, LKML List-ID: On Mon, Sep 28, 2009 at 04:57:41AM +0200, Nick Piggin wrote: > On Mon, Sep 28, 2009 at 03:19:43AM +0200, Andi Kleen wrote: > > > There is no real rush AFAIKS to fix this one single pagecache site > > > while we have problems with slab allocators and all other unaudited > > > places that nonatomically modify page flags with an elevated > > > > hwpoison ignores slab pages. > > "ignores" them *after* it has already written to page flags? > By that time it's too late. Yes, currently the page lock comes first. The only exception is for page count == 0 pages. I suppose we could move the slab check up, but then it only helps when slab is set. So if you make slab use refcount == 0 pages that would help. > Well it's fundamentally badly buggy, rare or not. We could avoid Let's put it like this -- any access to the poisoned cache lines in that page will trigger a panic anyways. -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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