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Wed, 02 Apr 2025 00:59:57 -0700 (PDT) Received: from [10.254.167.15] ([139.177.225.240]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7398cd1cc3dsm7041680b3a.80.2025.04.02.00.59.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 02 Apr 2025 00:59:57 -0700 (PDT) Message-ID: Date: Wed, 2 Apr 2025 15:59:51 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: page_alloc: Remove redundant READ_ONCE To: Songtang Liu , akpm@linux-foundation.org, ying.huang@linux.alibaba.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, zhengqi.arch@bytedance.com, songmuchun@bytedance.com References: From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Stat-Signature: w3ueprtc6djdq8bg5k64f7nrc1zwzaoi X-Rspam-User: X-Rspamd-Queue-Id: 24BCD120008 X-HE-Tag: 1743580798-5005 X-HE-Meta: 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 1Aw/wO+N nWpQe1ZfJenRCHYtazuJXgFHJ0S62N5LvLdxr7V2w9wsPkVbrfEOVptJtv3FXK9vjLCnuJTyk4vlJK7c5jujz3d6kBg== 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: List-Subscribe: List-Unsubscribe: On 4/2/25 3:41 PM, Songtang Liu wrote: > In the current code, batch is a local variable, and it cannot be > concurrently modified. It's unnecessary to use READ_ONCE here, > so remove it. > > Fixes: 51a755c56dc0 ("mm: tune PCP high automatically") > Signed-off-by: Songtang Liu > --- > mm/page_alloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index e3ea5bf5c459..6edc6e57d4f8 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2661,7 +2661,7 @@ static void free_frozen_page_commit(struct zone *zone, > free_high = (pcp->free_count >= batch && > (pcp->flags & PCPF_PREV_FREE_HIGH_ORDER) && > (!(pcp->flags & PCPF_FREE_HIGH_BATCH) || > - pcp->count >= READ_ONCE(batch))); > + pcp->count >= batch)); > pcp->flags |= PCPF_PREV_FREE_HIGH_ORDER; > } else if (pcp->flags & PCPF_PREV_FREE_HIGH_ORDER) { > pcp->flags &= ~PCPF_PREV_FREE_HIGH_ORDER; Reviewed-by: Qi Zheng Thanks!