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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 5C6AAC4332D for ; Thu, 19 Mar 2020 17:13:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 334A72072D for ; Thu, 19 Mar 2020 17:13:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584638021; bh=BbmwAERRRS1bmDmbsbyiruAsO6izlpHX+Ls+BqtqZyE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=dzpvvSo+W1lIj/mXq5HnjObUx1noT/R1rk3BpjY8cl3E79oAE9Jlht7DENKh9Zmam Vh6amk2LiNkpP624m7Zw9Hp6f1K9w/bkbvS+FWrjy+jyyI0MVGwcrode6LYOBjgeml ZDxXdmPL11T/c8EkTFY9BhQFsu5y3aMGairDo/Iw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728451AbgCSRNk (ORCPT ); Thu, 19 Mar 2020 13:13:40 -0400 Received: from mail-wm1-f68.google.com ([209.85.128.68]:53965 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727381AbgCSRNj (ORCPT ); Thu, 19 Mar 2020 13:13:39 -0400 Received: by mail-wm1-f68.google.com with SMTP id 25so3424777wmk.3 for ; Thu, 19 Mar 2020 10:13:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=mjce+PtajvBrnNU6PU3NbzED18KwcHrcpD9gbDuRtfI=; b=OVixnNatsngFUyIQUpgSYS3nBBwK3mU0sBbivnosTpMa9UfZQB3ydr1Ulcq4uG6dP3 KS8QlsoNiqqprZfbYxaiTk9rTkHSWnqs6gLi8foASzUgHr7t7nnr2T1oi/9ZKSnggvNi T/YAYj6VhJ+V8Xyz58NaWEtlZl0qzDnDn+8RzJHANcnNrLHb57GoqaIspf/L0hRssmGd NOck2CH92Q0ryidHng8XfdnVJpTKh9hGGnCq/dvS+qaTJRd4L4SauAn2RF3JoIk+SA1p YrEVVSlfCjVzq8p1ZlPCUmlChPbsAUaKRnXaCY+e7EcYJ5JPPLKosMAufdIAo0n9P491 FFQg== X-Gm-Message-State: ANhLgQ253zoXEVeSvtShpfmFpGEqodzKgpuNYT4c8+RluE1zqbkgomsQ Bm58gdhqm9KxoRIhHhvO2vM= X-Google-Smtp-Source: ADFU+vt9yj55QpEIdAl5B4oDZ7rybmPOo/HI7euCOLhJ6V8N5Ra/j0xMqNNJkJEPaz27A4ujJPEm6w== X-Received: by 2002:a1c:147:: with SMTP id 68mr4966843wmb.28.1584638016173; Thu, 19 Mar 2020 10:13:36 -0700 (PDT) Received: from localhost (ip-37-188-140-107.eurotel.cz. [37.188.140.107]) by smtp.gmail.com with ESMTPSA id g3sm4544841wro.93.2020.03.19.10.13.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Mar 2020 10:13:35 -0700 (PDT) Date: Thu, 19 Mar 2020 18:13:34 +0100 From: Michal Hocko To: mateusznosek0@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Johannes Weiner Subject: Re: [PATCH] mm/vmscan.c: Clean code by removing unnecessary assignment Message-ID: <20200319171334.GK20800@dhcp22.suse.cz> References: <20200319165938.23354-1-mateusznosek0@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200319165938.23354-1-mateusznosek0@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is usually preferable to Cc author of the code (added Johannes) On Thu 19-03-20 17:59:38, mateusznosek0@gmail.com wrote: > From: Mateusz Nosek > > Previously 0 was assigned to 'sc->skipped_deactivate'. It could happen only > if 'sc->skipped_deactivate' was 0 so the assignment is unnecessary and can > be removed. The above wording was a bit hard to understdand for me. I would go with " sc->memcg_low_skipped resets skipped_deactivate to 0 but this is not needed as this code path is never reachable with skipped_deactivate != 0 due to previous sc->skipped_deactivate branch. " > Signed-off-by: Mateusz Nosek The patch is correct. I am not sure it results in a better code though. I will defer to Johannes here. I suspect he simply wanted to express that skipped_deactivate should be always reset when retrying the direct reclaim. After this patch this could be lost in future changes so the code would be more subtle. But I am only guessing here. > --- > mm/vmscan.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index dca623db51c8..453ff2abcb58 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -3093,7 +3093,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, > if (sc->memcg_low_skipped) { > sc->priority = initial_priority; > sc->force_deactivate = 0; > - sc->skipped_deactivate = 0; > sc->memcg_low_reclaim = 1; > sc->memcg_low_skipped = 0; > goto retry; > -- > 2.17.1 -- Michal Hocko SUSE Labs