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[2003:d8:2f28:4600:d3a7:6c26:54cf:e01e]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-43fd16b2dc6sm2784471cf.63.2024.05.27.00.18.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 May 2024 00:18:17 -0700 (PDT) Message-ID: <18ad1a9f-8f00-41c1-9c77-ac3252061852@redhat.com> Date: Mon, 27 May 2024 09:18:13 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] mm/ksm: refactor out try_to_merge_with_zero_page() To: Chengming Zhou , 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> From: David Hildenbrand In-Reply-To: <36d4f3a6-c426-4455-b5be-2ab503d380ad@linux.dev> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 9D7DDA0003 X-Stat-Signature: maxj7qt9sxz9zhnonsqcrh3wunnp39gu X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1716794302-528320 X-HE-Meta: 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 W9QuKnNT 7kk5sYFWz8AxwIM09bZ3hv3gGNQ4ktAGtYWT9PpMKDfSCONTlBoLTCWBtzF+22IW7AkF+MK2m7kjnIRkrV9WbrQnjdZc51YYm49CwBULF5trNYn/css/CiT0fIoPgcKw1tivJuyWRVaGVIc0ZuEzn7yaDxpzTucW/L9dm0FGBhY8MM84XsndcPd4LMw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.001212, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. -- Thanks, David / dhildenb