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=-15.7 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 autolearn=ham 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 BB720C4361B for ; Tue, 15 Dec 2020 03:12:21 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 53E882246B for ; Tue, 15 Dec 2020 03:12:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 53E882246B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E42428D005E; Mon, 14 Dec 2020 22:12:20 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E172A8D001C; Mon, 14 Dec 2020 22:12:20 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D2ECD8D005E; Mon, 14 Dec 2020 22:12:20 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0143.hostedemail.com [216.40.44.143]) by kanga.kvack.org (Postfix) with ESMTP id BE08F8D001C for ; Mon, 14 Dec 2020 22:12:20 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 8771C2481 for ; Tue, 15 Dec 2020 03:12:20 +0000 (UTC) X-FDA: 77594043240.17.mouth60_3d0cd0d27420 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id 6A5DA180D0194 for ; Tue, 15 Dec 2020 03:12:20 +0000 (UTC) X-HE-Tag: mouth60_3d0cd0d27420 X-Filterd-Recvd-Size: 3029 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf26.hostedemail.com (Postfix) with ESMTP for ; Tue, 15 Dec 2020 03:12:19 +0000 (UTC) Date: Mon, 14 Dec 2020 19:12:18 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1608001939; bh=DQulYV7MUL1RIYKAKr9fLbe9t8QNlfh90DoBBw7CUjY=; h=From:To:Subject:In-Reply-To:From; b=bOGt8SB4ZJltlxWTf99s7SLCFGltLgOXxwweDcQiESiOJZQqkwVupT5WKzVGXktaM RGZxZ0pCLXDeshX6K2wUqshux4RjNIPC3M/Szj3XisP3Ju5nZq5hyCSvqBFxKQOAIK hkjXXHFvAIDg73CiZxHqNe3xXxxRjAvfH6KJZfcs= From: Andrew Morton To: akpm@linux-foundation.org, linux-mm@kvack.org, lukas.bulwahn@gmail.com, mgorman@techsingularity.net, mhocko@suse.com, mm-commits@vger.kernel.org, natechancellor@gmail.com, ndesaulniers@google.com, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 153/200] mm/vmscan: drop unneeded assignment in kswapd() Message-ID: <20201215031218.YvsVwzUwY%akpm@linux-foundation.org> In-Reply-To: <20201214190237.a17b70ae14f129e2dca3d204@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Lukas Bulwahn Subject: mm/vmscan: drop unneeded assignment in kswapd() The refactoring to kswapd() in commit e716f2eb24de ("mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx") turned an assignment to reclaim_order into a dead store, as in all further paths, reclaim_order will be assigned again before it is used. make clang-analyzer on x86_64 tinyconfig caught my attention with: mm/vmscan.c: warning: Although the value stored to 'reclaim_order' is used in the enclosing expression, the value is never actually read from 'reclaim_order' [clang-analyzer-deadcode.DeadStores] Compilers will detect this unneeded assignment and optimize this anyway. So, the resulting binary is identical before and after this change. Simplify the code and remove unneeded assignment to make clang-analyzer happy. No functional change. No change in binary code. Link: https://lkml.kernel.org/r/20201004125827.17679-1-lukas.bulwahn@gmail.com Signed-off-by: Lukas Bulwahn Acked-by: Mel Gorman Cc: Vlastimil Babka Cc: Michal Hocko Cc: Nathan Chancellor Cc: Nick Desaulniers Signed-off-by: Andrew Morton --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/vmscan.c~mm-vmscan-drop-unneeded-assignment-in-kswapd +++ a/mm/vmscan.c @@ -3895,7 +3895,7 @@ kswapd_try_sleep: highest_zoneidx); /* Read the new order and highest_zoneidx */ - alloc_order = reclaim_order = READ_ONCE(pgdat->kswapd_order); + alloc_order = READ_ONCE(pgdat->kswapd_order); highest_zoneidx = kswapd_highest_zoneidx(pgdat, highest_zoneidx); WRITE_ONCE(pgdat->kswapd_order, 0); _