From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx153.postini.com [74.125.245.153]) by kanga.kvack.org (Postfix) with SMTP id 5E6DD6B0005 for ; Thu, 31 Jan 2013 18:35:55 -0500 (EST) From: Naoya Horiguchi Subject: Re: [PATCH] HWPOISON: fix wrong num_poisoned_pages in handling memory error on thp Date: Thu, 31 Jan 2013 18:35:45 -0500 Message-Id: <1359675345-23262-1-git-send-email-n-horiguchi@ah.jp.nec.com> In-Reply-To: <20130131113416.963b5f07.akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Naoya Horiguchi , Andi Kleen , Tony Luck , Wu Fengguang , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Jan 31, 2013 at 11:34:16AM -0800, Andrew Morton wrote: > On Thu, 31 Jan 2013 10:25:58 -0500 > Naoya Horiguchi wrote: > > > num_poisoned_pages counts up the number of pages isolated by memory errors. > > But for thp, only one subpage is isolated because memory error handler > > splits it, so it's wrong to add (1 << compound_trans_order). > > > > ... > > > > --- mmotm-2013-01-23-17-04.orig/mm/memory-failure.c > > +++ mmotm-2013-01-23-17-04/mm/memory-failure.c > > @@ -1039,7 +1039,14 @@ int memory_failure(unsigned long pfn, int trapno, int flags) > > return 0; > > } > > > > - nr_pages = 1 << compound_trans_order(hpage); > > + /* > > + * If a thp is hit by a memory failure, it's supposed to be split. > > + * So we should add only one to num_poisoned_pages for that case. > > + */ > > + if (PageHuge(p)) > > /* > * PageHuge() only returns true for hugetlbfs pages, but not for normal or > * transparent huge pages. See the PageTransHuge() documentation for more > * details. > */ > int PageHuge(struct page *page) > { Do you mean that my comment refers to thp but this if-condition uses PageHuge so it's confusing, right? And yes, that's right, so I want to change this comment like this: /* * Currently errors on hugetlbfs pages are contained in hugepage * unit, so nr_pages should be 1 << compound_order. OTOH when * errors are on transparent hugepages, they are supposed to be * split and error containment is done in normal page unit. * So nr_pages should be one in this case. */ > > > + nr_pages = 1 << compound_trans_order(hpage); I should've used compound_order because this code is run only for hugetlbfs pages. > > + else /* normal page or thp */ > > + nr_pages = 1; > > atomic_long_add(nr_pages, &num_poisoned_pages); > > > > /* 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