From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4CDBC433E6 for ; Fri, 22 Jan 2021 19:00:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C23323AC6 for ; Fri, 22 Jan 2021 19:00:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728482AbhAVS7x (ORCPT ); Fri, 22 Jan 2021 13:59:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:38994 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728497AbhAVOTF (ORCPT ); Fri, 22 Jan 2021 09:19:05 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5EF3E23A81; Fri, 22 Jan 2021 14:14:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1611324843; bh=dqGUvUBkEm7zi2253iOe4HOAdThnyzo+tphPO9YCnLY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dRjKir+mS8UZnGQlNC8ddTx04Zu/SPO415bENlxPdILQEyX7kwy6ejTpvaO9PDmUa V6Nkfa3LFotfiK6RjJBNRJ4m6D/cKiiBYv+9XIE6XsMPC0yvJupTqCMxC/Cfmfv5+4 5qzL5Js6rlJjxDNLEkkCedgeKk+Mw3ErzLZVVkfs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , David Rientjes , Joonsoo Kim , Christoph Lameter , Pekka Enberg , Andrew Morton , Linus Torvalds Subject: [PATCH 4.14 27/50] mm, slub: consider rest of partial list if acquire_slab() fails Date: Fri, 22 Jan 2021 15:12:08 +0100 Message-Id: <20210122135736.291270624@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210122135735.176469491@linuxfoundation.org> References: <20210122135735.176469491@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jann Horn commit 8ff60eb052eeba95cfb3efe16b08c9199f8121cf upstream. acquire_slab() fails if there is contention on the freelist of the page (probably because some other CPU is concurrently freeing an object from the page). In that case, it might make sense to look for a different page (since there might be more remote frees to the page from other CPUs, and we don't want contention on struct page). However, the current code accidentally stops looking at the partial list completely in that case. Especially on kernels without CONFIG_NUMA set, this means that get_partial() fails and new_slab_objects() falls back to new_slab(), allocating new pages. This could lead to an unnecessary increase in memory fragmentation. Link: https://lkml.kernel.org/r/20201228130853.1871516-1-jannh@google.com Fixes: 7ced37197196 ("slub: Acquire_slab() avoid loop") Signed-off-by: Jann Horn Acked-by: David Rientjes Acked-by: Joonsoo Kim Cc: Christoph Lameter Cc: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/slub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/slub.c +++ b/mm/slub.c @@ -1846,7 +1846,7 @@ static void *get_partial_node(struct kme t = acquire_slab(s, n, page, object == NULL, &objects); if (!t) - break; + continue; /* cmpxchg raced */ available += objects; if (!object) {