From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) (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 E7BA122338 for ; Mon, 27 May 2024 07:41:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716795714; cv=none; b=mW5CE8mDMAB+OZclLQtIDa9eIHy8V5Z76vudz6QlmZIijnQLr1G412cC+VxmOFt/ukYGOfrgk//Duvmw1Ob3rulv0d4vHn8CN2+PWIUrfOUtKG33cRVhUbBsQtnbvZ6Ncuo44OjCaBHyMnWgJdqDTZSDo01h2yPy8ursqqnBLmI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716795714; c=relaxed/simple; bh=3Rr1HaG9tG9vsr3RvcnFDKNXwGd3bAmbX0F/s1f15pQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ciATLMXunvwyK1ZCELXGfqhUnANcj7qGPRaD4gC1D7Ii0ROmZnNMPNfF0KnCSgFLKgna/vIX8PPRV9eGUIA0n6mRMPUmZTdeT7H+MY7qFrHLYJeDZNhSStbqN/vVC8X5tPSVdJGoo5EXSPxKqtA15nzGfNxEn9vLoRTfBjWAO0s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=CLJCQTE/; arc=none smtp.client-ip=95.215.58.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="CLJCQTE/" X-Envelope-To: david@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1716795709; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=A8ih7vz66Rx+ZxVaMPrr50Ps6h1emlB7JWpOfQ6g6+8=; b=CLJCQTE/vly7FuFm/O96eANqAlO1xjq4WZyQtTRg7+o7S3z8nAA/pw9hHG7z8v6UmUVWEj DAsGh4R23PM3h1mMP9uGubp94rSQC5EifT1BGP+atzIxVzxjwpG8oi+kRoBoe5dQpL7jAO QeQn9+WSoa/zkivs6BVf4vfdAZon4Es= X-Envelope-To: akpm@linux-foundation.org X-Envelope-To: aarcange@redhat.com X-Envelope-To: hughd@google.com X-Envelope-To: shr@devkernel.io X-Envelope-To: linux-mm@kvack.org X-Envelope-To: linux-kernel@vger.kernel.org X-Envelope-To: zhouchengming@bytedance.com Message-ID: Date: Mon, 27 May 2024 15:41:21 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 1/4] mm/ksm: refactor out try_to_merge_with_zero_page() Content-Language: en-US To: David Hildenbrand , Andrew Morton , aarcange@redhat.com, hughd@google.com, shr@devkernel.io Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, zhouchengming@bytedance.com References: <20240524-b4-ksm-scan-optimize-v1-0-053b31bd7ab4@linux.dev> <20240524-b4-ksm-scan-optimize-v1-1-053b31bd7ab4@linux.dev> <18259f7c-d57e-4504-91ec-90b7c87aad01@redhat.com> <36d4f3a6-c426-4455-b5be-2ab503d380ad@linux.dev> <18ad1a9f-8f00-41c1-9c77-ac3252061852@redhat.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: <18ad1a9f-8f00-41c1-9c77-ac3252061852@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 2024/5/27 15:18, David Hildenbrand wrote: > Am 27.05.24 um 06:36 schrieb Chengming Zhou: >> On 2024/5/24 23:12, David Hildenbrand wrote: >>> On 24.05.24 10:56, Chengming Zhou wrote: >>>> In preparation for later changes, refactor out a new function called >>>> try_to_merge_with_zero_page(), which tries to merge with zero page. >>>> >>>> Signed-off-by: Chengming Zhou >>>> --- >>>>    mm/ksm.c | 67 +++++++++++++++++++++++++++++++++++----------------------------- >>>>    1 file changed, 37 insertions(+), 30 deletions(-) >>>> >>>> diff --git a/mm/ksm.c b/mm/ksm.c >>>> index 4dc707d175fa..cbd4ba7ea974 100644 >>>> --- a/mm/ksm.c >>>> +++ b/mm/ksm.c >>>> @@ -1531,6 +1531,41 @@ static int try_to_merge_one_page(struct vm_area_struct *vma, >>>>        return err; >>>>    } >>>>    +/* This function returns 0 if the pages were merged, -EFAULT otherwise. */ >>> >>> No it doesn't. Check the "err = 0" case. >>> >> >> Right, how about this: This function returns 0 if the page were merged or the vma >> is out of date, which means we don't need to continue, -EFAULT otherwise. > > Maybe slightly adjusted: > > This function returns 0 if the pages were merged or if they are no longer merging candidates (e.g., VMA stale), -EFAULT otherwise. > Great, will change to this. Thanks!