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[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