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Tue, 08 Aug 2023 08:16:53 -0400 Date: Tue, 8 Aug 2023 08:16:51 -0400 From: Hugo Villeneuve To: Miaohe Lin Cc: , , Message-Id: <20230808081651.0d8573551f87de016c018529@hugovil.com> In-Reply-To: <20230808020555.658430-1-linmiaohe@huawei.com> References: <20230808020555.658430-1-linmiaohe@huawei.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 184.161.19.61 X-SA-Exim-Mail-From: hugo@hugovil.com Subject: Re: [PATCH] mm/page_alloc: remove unneeded current_order check X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on mail.hugovil.com) X-Rspamd-Queue-Id: 2C5A2C000B X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: zbqn1esbby43u5o4siy18mb9ddrafyg5 X-HE-Tag: 1691497015-984435 X-HE-Meta: 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 N33SXeaN LTMq6jiC9qNF47N0Dvx5vPumEDRBRgo1z9xjRWRdqVNPOf5OheSOSDw7jNvacFtX//RpMRXUQKQIpBt6J/1Fxd2WkznSiQD1A+PodDEHqWXlsZ7OjQTR4czfz1iyo8yJHOCIFgdyPG4kNNF9ekvvQL4yuD9rEIFolc6xncmfFmP0gzP8LkW2d0/4j4ZkgV8DJqWAgCOOQIJhky4DymErmV5nrRSi9t7L8lzwE8vdZ6jYwfJM= 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: On Tue, 8 Aug 2023 10:05:55 +0800 Miaohe Lin wrote: > current_order is guaranteed to '>=' min_order while min_order always '>=' > order. So current_order must be '>=' order. > > Signed-off-by: Miaohe Lin > --- > mm/page_alloc.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 96b7c1a7d1f2..d37ec87515d0 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2072,8 +2072,7 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype, > * allocation falls back into a different pageblock than this > * one, it won't cause permanent fragmentation. > */ > - if (!can_steal && start_migratetype == MIGRATE_MOVABLE > - && current_order > order) > + if (!can_steal && start_migratetype == MIGRATE_MOVABLE) > goto find_smallest; Hi, if my analysis is correct, min_order can be initialized to the value of order before the loop begins. In that case, in the last loop iteration, current_order will be equal to min_order and also to order. The condition 'current_order > order' will evaluate to false, and the 'if' block should not be executed? Hugo.