From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx125.postini.com [74.125.245.125]) by kanga.kvack.org (Postfix) with SMTP id AC66D6B0044 for ; Thu, 23 Aug 2012 16:31:17 -0400 (EDT) From: Naoya Horiguchi Subject: Re: [PATCH 1/3] HWPOISON: fix action_result() to print out dirty/clean Date: Thu, 23 Aug 2012 16:31:09 -0400 Message-Id: <1345753869-31053-1-git-send-email-n-horiguchi@ah.jp.nec.com> In-Reply-To: <20120823093330.GC12745@localhost> Sender: owner-linux-mm@kvack.org List-ID: To: Wu Fengguang Cc: Naoya Horiguchi , Andi Kleen , Andrew Morton , Tony Luck , Rik van Riel , Jun'ichi Nomura , linux-mm@kvack.org, linux-kernel@vger.kernel.org Hello, Thank you for your review. On Thu, Aug 23, 2012 at 05:33:30PM +0800, Fengguang Wu wrote: > On Wed, Aug 22, 2012 at 11:17:33AM -0400, Naoya Horiguchi wrote: > > action_result() fails to print out "dirty" even if an error occurred on a > > dirty pagecache, because when we check PageDirty in action_result() it was > > cleared after page isolation even if it's dirty before error handling. This > > can break some applications that monitor this message, so should be fixed. > > > > There are several callers of action_result() except page_action(), but > > either of them are not for LRU pages but for free pages or kernel pages, > > so we don't have to consider dirty or not for them. > > > > Signed-off-by: Naoya Horiguchi > > Reviewed-by: Andi Kleen > > --- > > mm/memory-failure.c | 22 +++++++++------------- > > 1 file changed, 9 insertions(+), 13 deletions(-) > > > > diff --git v3.6-rc1.orig/mm/memory-failure.c v3.6-rc1/mm/memory-failure.c > > index a6e2141..79dfb2f 100644 > > --- v3.6-rc1.orig/mm/memory-failure.c > > +++ v3.6-rc1/mm/memory-failure.c > > @@ -779,16 +779,16 @@ static struct page_state { > > { compound, compound, "huge", me_huge_page }, > > #endif > > > > - { sc|dirty, sc|dirty, "swapcache", me_swapcache_dirty }, > > - { sc|dirty, sc, "swapcache", me_swapcache_clean }, > > + { sc|dirty, sc|dirty, "dirty swapcache", me_swapcache_dirty }, > > + { sc|dirty, sc, "clean swapcache", me_swapcache_clean }, > > > > - { unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty}, > > - { unevict, unevict, "unevictable LRU", me_pagecache_clean}, > > + { unevict|dirty, unevict|dirty, "dirty unevictable LRU", me_pagecache_dirty }, > > + { unevict, unevict, "clean unevictable LRU", me_pagecache_clean }, > > > > - { mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty }, > > - { mlock, mlock, "mlocked LRU", me_pagecache_clean }, > > + { mlock|dirty, mlock|dirty, "dirty mlocked LRU", me_pagecache_dirty }, > > + { mlock, mlock, "clean mlocked LRU", me_pagecache_clean }, > > > > - { lru|dirty, lru|dirty, "LRU", me_pagecache_dirty }, > > + { lru|dirty, lru|dirty, "dirty LRU", me_pagecache_dirty }, > > { lru|dirty, lru, "clean LRU", me_pagecache_clean }, > > According to the set_page_dirty() comment, the dirty bit might be set > outside the page lock (however I don't know any concrete examples). > That means the word "clean" is not 100% right. That's probably why we > only report "dirty LRU" and didn't say "clean LRU". So this doesn't seem to be just a messaging problem. If PageDirty is set outside page lock, we can handle the dirty page only with me_pagecache_clean(), without me_pagecache_dirty(). It might be a good idea to add some check code to detect such kind of race and give up error isolation if it does. I'll dig into who sets dirty flags outside/inside page locks, and look for a workaround. (But it will be in another patch...) Thanks, Naoya -- 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