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=-6.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 7F213C3279D for ; Tue, 6 Oct 2020 20:51:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4EEE42087E for ; Tue, 6 Oct 2020 20:51:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727390AbgJFUvU (ORCPT ); Tue, 6 Oct 2020 16:51:20 -0400 Received: from mga05.intel.com ([192.55.52.43]:27136 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727300AbgJFUvP (ORCPT ); Tue, 6 Oct 2020 16:51:15 -0400 IronPort-SDR: j5p73I4hSQrNQB/jcYmhdIv4insEGKsU87yFoWPWjBm5l0u2YEfgmm2gSIKckm32bApLRdqvsW hvNyRkmFSXZQ== X-IronPort-AV: E=McAfee;i="6000,8403,9766"; a="249395727" X-IronPort-AV: E=Sophos;i="5.77,343,1596524400"; d="scan'208";a="249395727" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Oct 2020 13:51:14 -0700 IronPort-SDR: 07FE8k4bQQiGdvF6iwrVvb6rTSKDHf8z7w4/FPh2mCU63yE8rm68z1SZkwYipXs7aIWWo8cD1t WEen5JSIOKCg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,343,1596524400"; d="scan'208";a="527582393" Received: from viggo.jf.intel.com (HELO localhost.localdomain) ([10.54.77.144]) by orsmga005.jf.intel.com with ESMTP; 06 Oct 2020 13:51:14 -0700 Subject: [RFC][PATCH 03/12] mm/vmscan: replace implicit RECLAIM_ZONE checks with explicit checks To: linux-kernel@vger.kernel.org Cc: Dave Hansen , ben.widawsky@intel.com, alex.shi@linux.alibaba.com, tobin@kernel.org, cl@linux.com, akpm@linux-foundation.org, ying.huang@intel.com, dan.j.williams@intel.com, cai@lca.pw, dwagner@suse.de From: Dave Hansen Date: Tue, 06 Oct 2020 13:51:10 -0700 References: <20201006205103.268F74A9@viggo.jf.intel.com> In-Reply-To: <20201006205103.268F74A9@viggo.jf.intel.com> Message-Id: <20201006205110.1E03E385@viggo.jf.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen RECLAIM_ZONE was assumed to be unused because it was never explicitly used in the kernel. However, there were a number of places where it was checked implicitly by checking 'node_reclaim_mode' for a zero value. These zero checks are not great because it is not obvious what a zero mode *means* in the code. Replace them with a helper which makes it more obvious: node_reclaim_enabled(). This helper also provides a handy place to explicitly check the RECLAIM_ZONE bit itself. Check it explicitly there to make it more obvious where the bit can affect behavior. This should have no functional impact. Signed-off-by: Dave Hansen Reviewed-by: Ben Widawsky Cc: Alex Shi Cc: "Tobin C. Harding" Cc: Christoph Lameter Cc: Andrew Morton Cc: Huang Ying Cc: Dan Williams Cc: Qian Cai Cc: Daniel Wagner -- Note: This is not cc'd to stable. It does not fix any bugs. --- b/include/linux/swap.h | 7 +++++++ b/mm/khugepaged.c | 2 +- b/mm/page_alloc.c | 2 +- 3 files changed, 9 insertions(+), 2 deletions(-) diff -puN include/linux/swap.h~mm-vmscan-node_reclaim_mode_helper include/linux/swap.h --- a/include/linux/swap.h~mm-vmscan-node_reclaim_mode_helper 2020-10-06 13:39:22.850818437 -0700 +++ b/include/linux/swap.h 2020-10-06 13:39:22.859818437 -0700 @@ -12,6 +12,7 @@ #include #include #include +#include #include struct notifier_block; @@ -381,6 +382,12 @@ extern int sysctl_min_slab_ratio; #define node_reclaim_mode 0 #endif +static inline bool node_reclaim_enabled(void) +{ + /* Is any node_reclaim_mode bit set? */ + return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP); +} + extern void check_move_unevictable_pages(struct pagevec *pvec); extern int kswapd_run(int nid); diff -puN mm/khugepaged.c~mm-vmscan-node_reclaim_mode_helper mm/khugepaged.c --- a/mm/khugepaged.c~mm-vmscan-node_reclaim_mode_helper 2020-10-06 13:39:22.852818437 -0700 +++ b/mm/khugepaged.c 2020-10-06 13:39:22.859818437 -0700 @@ -794,7 +794,7 @@ static bool khugepaged_scan_abort(int ni * If node_reclaim_mode is disabled, then no extra effort is made to * allocate memory locally. */ - if (!node_reclaim_mode) + if (!node_reclaim_enabled()) return false; /* If there is a count for this node already, it must be acceptable */ diff -puN mm/page_alloc.c~mm-vmscan-node_reclaim_mode_helper mm/page_alloc.c --- a/mm/page_alloc.c~mm-vmscan-node_reclaim_mode_helper 2020-10-06 13:39:22.855818437 -0700 +++ b/mm/page_alloc.c 2020-10-06 13:39:22.862818437 -0700 @@ -3802,7 +3802,7 @@ retry: if (alloc_flags & ALLOC_NO_WATERMARKS) goto try_this_zone; - if (node_reclaim_mode == 0 || + if (!node_reclaim_enabled() || !zone_allows_reclaim(ac->preferred_zoneref->zone, zone)) continue; _