From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754521AbbGRAwH (ORCPT ); Fri, 17 Jul 2015 20:52:07 -0400 Received: from mail-pd0-f177.google.com ([209.85.192.177]:33037 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752015AbbGRAwF (ORCPT ); Fri, 17 Jul 2015 20:52:05 -0400 From: Sergey Senozhatsky To: Minchan Kim Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [PATCH v3] zsmalloc: do not take class lock in zs_shrinker_count() Date: Sat, 18 Jul 2015 09:51:05 +0900 Message-Id: <1437180665-3607-1-git-send-email-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.4.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We can avoid taking class ->lock around zs_can_compact() in zs_shrinker_count(), because the number that we return back is outdated in general case, by design. We have different sources that are able to change class's state right after we return from zs_can_compact() -- ongoing I/O operations, manually triggered compaction, or two of them happening simultaneously. We re-do this calculations during compaction on a per class basis anyway. zs_unregister_shrinker() will not return until we have an active shrinker, so classes won't unexpectedly disappear while zs_shrinker_count() iterates them. Signed-off-by: Sergey Senozhatsky Acked-by: Minchan Kim --- mm/zsmalloc.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 1edd8a0..c1399e8 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -1711,8 +1711,6 @@ static struct page *isolate_source_page(struct size_class *class) * * Based on the number of unused allocated objects calculate * and return the number of pages that we can free. - * - * Should be called under class->lock. */ static unsigned long zs_can_compact(struct size_class *class) { @@ -1836,9 +1834,7 @@ static unsigned long zs_shrinker_count(struct shrinker *shrinker, if (class->index != i) continue; - spin_lock(&class->lock); pages_to_free += zs_can_compact(class); - spin_unlock(&class->lock); } return pages_to_free; -- 2.4.6