From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759494AbcAUMJu (ORCPT ); Thu, 21 Jan 2016 07:09:50 -0500 Received: from mga09.intel.com ([134.134.136.24]:53324 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759324AbcAUMJg (ORCPT ); Thu, 21 Jan 2016 07:09:36 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,325,1449561600"; d="scan'208";a="898050998" From: "Kirill A. Shutemov" To: Andrew Morton , Andrea Arcangeli Cc: Hugh Dickins , Dave Hansen , Mel Gorman , Rik van Riel , Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Steve Capper , "Aneesh Kumar K.V" , Johannes Weiner , Michal Hocko , Jerome Marchand , Sasha Levin , linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" Subject: [PATCH 3/3] thp: limit number of object to scan on deferred_split_scan() Date: Thu, 21 Jan 2016 15:09:23 +0300 Message-Id: <1453378163-133609-4-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.7.0.rc3 In-Reply-To: <1453378163-133609-1-git-send-email-kirill.shutemov@linux.intel.com> References: <20160121012237.GE7119@redhat.com> <1453378163-133609-1-git-send-email-kirill.shutemov@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If we have a lot of pages in queue to be split, deferred_split_scan() can spend unreasonable amount of time under spinlock with disabled interrupts. Let's cap number of pages to split on scan by sc->nr_to_scan. Signed-off-by: Kirill A. Shutemov Reported-by: Andrea Arcangeli --- mm/huge_memory.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 36f98459f854..298dbc001b07 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3478,17 +3478,19 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, int split = 0; spin_lock_irqsave(&pgdata->split_queue_lock, flags); - list_splice_init(&pgdata->split_queue, &list); - /* Take pin on all head pages to avoid freeing them under us */ list_for_each_safe(pos, next, &list) { page = list_entry((void *)pos, struct page, mapping); page = compound_head(page); - /* race with put_compound_page() */ - if (!get_page_unless_zero(page)) { + if (get_page_unless_zero(page)) { + list_move(page_deferred_list(page), &list); + } else { + /* We lost race with put_compound_page() */ list_del_init(page_deferred_list(page)); pgdata->split_queue_len--; } + if (!--sc->nr_to_scan) + break; } spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); -- 2.7.0.rc3