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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v2 1/2] mm/page_alloc: drop the unnecessary pfn_valid() for start pfn To: Michal Hocko Cc: akpm@linux-foundation.org, rppt@kernel.org, ying.huang@intel.com, mgorman@techsingularity.net, vbabka@suse.cz, david@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <9fc85cce8908938f4fd75ff50bc981c073779aa5.1682229876.git.baolin.wang@linux.alibaba.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 30AFB1A0003 X-Stat-Signature: 1zyf9kkpgb1gozy7rmzndbio7kmfj8yw X-Rspam-User: X-HE-Tag: 1682333205-230896 X-HE-Meta: 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 DKmr8J2Y zBBQg5apQc0/yVi4NPzwetHc8LN4gZ93S8N+NHh44Buqd+jA9GaHnOgDzhvoIdBz+t5/3ImM2rePiA1dhiY5uHTs8/5ii+ewNsrR2NS0/A5EWsKQLtJFRCgsW6YHd3PElQQ8OOjMqWDi9guFYdPbWMJSg7iYgzbaXJ2L3zF+9Jez4UWpcE1n0jHLOfkLhIskWXip16bPEZ5BL2nA= 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 4/24/2023 5:50 PM, Michal Hocko wrote: > On Sun 23-04-23 18:59:10, Baolin Wang wrote: >> We've already used pfn_to_online_page() for start pfn to make sure > > Who is we? I do not see any note explicitly requiring that start_pfn has > to be valid for __pageblock_pfn_to_page. Sorry for confusing, what I mean is the __pageblock_pfn_to_page() function, which has used pfn_to_online_page() for start pfn. So the pfn_valid() in __pageblock_pfn_to_page() for start pfn is unnecessary. I will update the commit log to make it clear. >> it is online and valid, so the pfn_valid() for the start pfn is >> unnecessary, drop it. >> >> Signed-off-by: Baolin Wang >> Reviewed-by: David Hildenbrand >> Reviewed-by: "Huang, Ying" >> --- >> Changes from v1: >> - Collect reviewed tags. Thanks David and Ying. >> --- >> 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 9de2a18519a1..6457b64fe562 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -1512,7 +1512,7 @@ struct page *__pageblock_pfn_to_page(unsigned long start_pfn, >> /* end_pfn is one past the range we are checking */ >> end_pfn--; >> >> - if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn)) >> + if (!pfn_valid(end_pfn)) >> return NULL; >> >> start_page = pfn_to_online_page(start_pfn); >> -- >> 2.27.0 >