From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ea0-f174.google.com (mail-ea0-f174.google.com [209.85.215.174]) by kanga.kvack.org (Postfix) with ESMTP id ABF566B0031 for ; Fri, 7 Feb 2014 17:01:04 -0500 (EST) Received: by mail-ea0-f174.google.com with SMTP id b10so1796221eae.5 for ; Fri, 07 Feb 2014 14:01:04 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id 43si10731947eeh.73.2014.02.07.14.01.02 for ; Fri, 07 Feb 2014 14:01:03 -0800 (PST) Date: Fri, 07 Feb 2014 17:00:19 -0500 From: Naoya Horiguchi Message-ID: <52f5579f.c3030e0a.4440.3f94SMTPIN_ADDED_BROKEN@mx.google.com> In-Reply-To: <20140207134329.a305b169351a2538ab03785f@linux-foundation.org> References: <52f54d29.89cfe00a.4277.4d3dSMTPIN_ADDED_BROKEN@mx.google.com> <20140207134329.a305b169351a2538ab03785f@linux-foundation.org> Subject: Re: [PATCH] mm/memory-failure.c: move refcount only in !MF_COUNT_INCREASED Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Andi Kleen , Wanpeng Li , gong.chen@linux.intel.com, linux-mm@kvack.org, Naoya Horiguchi On Fri, Feb 07, 2014 at 01:43:29PM -0800, Andrew Morton wrote: > On Fri, 07 Feb 2014 16:16:04 -0500 Naoya Horiguchi wrote: > > > # Resending due to sending failure. Sorry if you received twice. > > --- > > mce-test detected a test failure when injecting error to a thp tail page. > > This is because we take page refcount of the tail page in madvise_hwpoison() > > while the fix in commit a3e0f9e47d5e ("mm/memory-failure.c: transfer page > > count from head page to tail page after split thp") assumes that we always > > take refcount on the head page. > > > > When a real memory error happens we take refcount on the head page where > > memory_failure() is called without MF_COUNT_INCREASED set, so it seems to me > > that testing memory error on thp tail page using madvise makes little sense. > > > > This patch cancels moving refcount in !MF_COUNT_INCREASED for valid testing. > > > > ... > > > > --- v3.14-rc1.orig/mm/memory-failure.c > > +++ v3.14-rc1/mm/memory-failure.c > > @@ -1042,8 +1042,10 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn, > > * to it. Similarly, page lock is shifted. > > */ > > if (hpage != p) { > > - put_page(hpage); > > - get_page(p); > > + if (!(flags && MF_COUNT_INCREASED)) { > > s/&&/&/ > > Please carefully retest this, make sure that both cases are covered? Sorry for silly mistake, flags is MF_COUNT_INCREASED from madvise() and 0 from /sys/devices/system/memory/soft_offline_page, so the above logic accidentally made no difference from the correct one in comparing with these two cases. I retested it and confirmed that replaced one fixes the problem. Thanks, Naoya --- From: Naoya Horiguchi Date: Fri, 7 Feb 2014 06:33:30 -0500 Subject: [PATCH v2] mm/memory-failure.c: move refcount only in !MF_COUNT_INCREASED mce-test detected a test failure when injecting error to a thp tail page. This is because we take page refcount of the tail page in madvise_hwpoison() while the fix in commit a3e0f9e47d5e ("mm/memory-failure.c: transfer page count from head page to tail page after split thp") assumes that we always take refcount on the head page. When a real memory error happens we take refcount on the head page where memory_failure() is called without MF_COUNT_INCREASED set, so it seems to me that testing memory error on thp tail page using madvise makes little sense. This patch cancels moving refcount in !MF_COUNT_INCREASED for valid testing. Signed-off-by: Naoya Horiguchi Cc: stable@vger.kernel.org # 3.9+: a3e0f9e47d5e --- mm/memory-failure.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index ab55d489eb05..b68d14d59784 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1042,8 +1042,10 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn, * to it. Similarly, page lock is shifted. */ if (hpage != p) { - put_page(hpage); - get_page(p); + if (!(flags & MF_COUNT_INCREASED)) { + put_page(hpage); + get_page(p); + } lock_page(p); unlock_page(hpage); *hpagep = p; -- 1.8.5.3 -- 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