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Sat, 16 Aug 2025 02:06:54 -0700 (PDT) Date: Sat, 16 Aug 2025 09:06:54 +0000 From: Wei Yang To: David Hildenbrand Cc: Lorenzo Stoakes , Wei Yang , akpm@linux-foundation.org, riel@surriel.com, Liam.Howlett@oracle.com, vbabka@suse.cz, harry.yoo@oracle.com, linux-mm@kvack.org Subject: Re: [PATCH 2/3] mm/rmap: could be partially_mapped only after no entire map Message-ID: <20250816090654.u5eoys2vkpswe553@master> Reply-To: Wei Yang References: <20250815084943.23063-1-richard.weiyang@gmail.com> <20250815084943.23063-3-richard.weiyang@gmail.com> <458c4ea9-1e33-4159-a545-6ad2c5b81add@lucifer.local> <15ccbbb0-8ebc-4c50-a1c8-fbe5416ecf46@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <15ccbbb0-8ebc-4c50-a1c8-fbe5416ecf46@redhat.com> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 3E2D1C0007 X-Stat-Signature: gt7ygw1du7prxixe9i8o13a6pk9x98k8 X-Rspam-User: X-HE-Tag: 1755335216-501416 X-HE-Meta: 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 r/eHHsjE 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 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 Sat, Aug 16, 2025 at 08:31:59AM +0200, David Hildenbrand wrote: >On 15.08.25 12:08, Lorenzo Stoakes wrote: >> On Fri, Aug 15, 2025 at 08:49:42AM +0000, Wei Yang wrote: >> > If it is not the last entire map, we are sure the folio is not partially >> > mapped. >> > >> > Move the check when there is no entire map. >> > >> >> This one I don't like, you're having to sit and think about why it is that >> this would be the case, vs. just unconditionally doing it. >> >> Again, as mentioned on previous series, just because we could do something >> doesn't mean we should, unless there's statistically reliable perf data on >> something real-world indicating we _must_, code clarity absolutely beats >> everything else on importance. >> >> So yeah, sorry but no to this patch, please resend with just the two >> reviewed (unless David radically disagrees with me :) > >The compiler can figure out that "nr == 0" if the "if (last)" branch is not >taken. > Per my understanding, last is a run time value. I don't figure out how compiler could help here. I may miss something. Would you mind giving more hint? >So I tend to prefer keeping it as is. >-- >Cheers > >David / dhildenb -- Wei Yang Help you, Help me