From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-110.freemail.mail.aliyun.com (out30-110.freemail.mail.aliyun.com [115.124.30.110]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 292F12E337B for ; Wed, 2 Apr 2025 08:30:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.110 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743582630; cv=none; b=e5sIl0fn89WqnR8FIBaDveiAV+KVatQjzpRTOT218hHjbJ47lHjZmCz0kdCLABMwcEYVODdqAW419DdQLU/NBOoolxwfYQjNXdh/qZAUiI85ft1J0sA1vJJNgL/hSMs0T05DCFGO0G8YkTbcR97c8h6beeSRSCf7kS6HsZY2+C4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743582630; c=relaxed/simple; bh=rK0JwRX7x93+AdZjMygjhNtrfe7HePAeND16fITKgX8=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=thQYPT+vLOQLfKFoXETA1B/hg5yc5DGfVZqMFOPSDKvC1FCSBbGsxkvhtBTe+f8MOadCJMgrDEeiIaUxIJjheLKxla4O1vb2ns8jE3x0SM641NOSF/RPusPoz4o9e1IxLXaA6zI189wtqjMmbmLO5IBDERBdROKZBJZ0zozm4No= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=OvdaTovz; arc=none smtp.client-ip=115.124.30.110 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="OvdaTovz" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1743582618; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; bh=l35Z6/eiF4yIEdG7KwDegt7nCGOLRyuKZvtVkhl+284=; b=OvdaTovz+cMRpYWNO5QTFkWhd676bn1eH1DwNGAGtlArdRbF3FvERA1D4BX6tJDO0n6WT0dUsfeuU9p2R0tQv1NvfYJ2lJkfc1s45pSvUBfUmWdlHneQOpT4gdOwo2h/XlBxhQFSN0fbrNErMl0zqzgbhgo/gBamm4njjMGKeNo= Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0WUIZmQM_1743582617 cluster:ay36) by smtp.aliyun-inc.com; Wed, 02 Apr 2025 16:30:18 +0800 From: "Huang, Ying" To: Songtang Liu Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, zhengqi.arch@bytedance.com, songmuchun@bytedance.com Subject: Re: [PATCH] mm: page_alloc: Remove redundant READ_ONCE In-Reply-To: (Songtang Liu's message of "Wed, 2 Apr 2025 03:41:16 -0400") References: Date: Wed, 02 Apr 2025 16:30:19 +0800 Message-ID: <87wmc3ufs4.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Songtang Liu writes: > 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)); Nice catch! Reviewed-by: Huang Ying > pcp->flags |= PCPF_PREV_FREE_HIGH_ORDER; > } else if (pcp->flags & PCPF_PREV_FREE_HIGH_ORDER) { > pcp->flags &= ~PCPF_PREV_FREE_HIGH_ORDER; --- Best Regards, Huang, Ying