From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx160.postini.com [74.125.245.160]) by kanga.kvack.org (Postfix) with SMTP id 0D38A6B0032 for ; Thu, 22 Aug 2013 15:06:21 -0400 (EDT) Date: Thu, 22 Aug 2013 15:06:05 -0400 From: Naoya Horiguchi Message-ID: <1377198365-3xic0o2q-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1377164907-24801-4-git-send-email-liwanp@linux.vnet.ibm.com> References: <1377164907-24801-1-git-send-email-liwanp@linux.vnet.ibm.com> <1377164907-24801-4-git-send-email-liwanp@linux.vnet.ibm.com> Subject: Re: [PATCH 4/6] mm/hwpoison: don't set migration type twice to avoid hold heavy contend zone->lock 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: Wanpeng Li Cc: Andrew Morton , Andi Kleen , Fengguang Wu , Tony Luck , gong.chen@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Aug 22, 2013 at 05:48:25PM +0800, Wanpeng Li wrote: > Set pageblock migration type will hold zone->lock which is heavy contended > in system to avoid race. However, soft offline page will set pageblock > migration type twice during get page if the page is in used, not hugetlbfs > page and not on lru list. There is unnecessary to set the pageblock migration > type and hold heavy contended zone->lock again if the first round get page > have already set the pageblock to right migration type. Can we use get_pageblock_migratetype() outside zone->lock? There are surely some users which call this function outside zone->lock like free_hot_cold_pages(), __free_pages, etc., but I think that there's a race window where migratetype is updated just after get_pageblock_migratetype() check. > Signed-off-by: Wanpeng Li > --- > mm/memory-failure.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 6bfd51e..3bfb45f 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1413,7 +1413,8 @@ static int __get_any_page(struct page *p, unsigned long pfn, int flags) > * was free. This flag should be kept set until the source page > * is freed and PG_hwpoison on it is set. > */ > - set_migratetype_isolate(p, true); > + if (get_pageblock_migratetype(p) == MIGRATE_ISOLATE) You meant '!=', right? Thanks, Naoya Horiguchi > + set_migratetype_isolate(p, true); > /* > * When the target page is a free hugepage, just remove it > * from free hugepage list. > -- > 1.8.1.2 > -- 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