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b=detDNI5LmlcWHMNgKnzoxCjD7vdWlvEuo9F87H+bTMV4IXIwptHvTrCa2E97ztjNMGEvts9CF196o3j94jfsJ86mA0NjsIgYh5W/bfhKCGGx6kZeOZbX/gdC3UB/3XFaSKMfq8oqV5bAlHCBfGPwIQC3FR4FguoqaSjxiJ2QOaU= Received: from 30.74.144.116(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0WuxwDsf_1765866131 cluster:ay36) by smtp.aliyun-inc.com; Tue, 16 Dec 2025 14:22:11 +0800 Message-ID: <9e038290-70ff-458d-b46d-bc512c3442be@linux.alibaba.com> Date: Tue, 16 Dec 2025 14:22:11 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] mm: rmap: support batched unmapping for file large folios To: Barry Song <21cnbao@gmail.com> Cc: Lorenzo Stoakes , akpm@linux-foundation.org, david@kernel.org, catalin.marinas@arm.com, will@kernel.org, ryan.roberts@arm.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, willy@infradead.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <70d1dedc-b4fc-4eb6-baf6-9e54b6a62249@lucifer.local> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 61BD9A0017 X-Rspamd-Server: rspam04 X-Stat-Signature: cs8es4f5mai3c3cq7mfffg3ratost7jp X-HE-Tag: 1765866135-245257 X-HE-Meta: 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 u51+44uG g33TBuqx+/jeQminbUqT5bnQRpFn3w9FB92CLSVYVk2HNRW7uKl25Ntj+m3ER9/kg7xnQtEd05Wzg9FLt3UUO1OfMgR16N9QJhwmaVSfuMrljGnlU+6AtktYIBUQqrsvrNWjql2s8jXtB0jCq9rAaDb4QKoSxbpjopPD8za2VQ6J6h2vSVq5+XQ8r3vJ2gtga7tWB7DTyRjC8v8toquLinWGSL1Lwxtocglk7cgxia26L3YUCmPY3vDQTD8w6IyL/dj9mYeJz5tbDfE0yX0ZXubrrfQbdwfS4dOJGUReDKqKhe90= 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 2025/12/16 14:13, Barry Song wrote: >>>> >>>> diff --git a/mm/rmap.c b/mm/rmap.c >>>> index ec232165c47d..4c9d5777c8da 100644 >>>> --- a/mm/rmap.c >>>> +++ b/mm/rmap.c >>>> @@ -1855,9 +1855,10 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio, >>>> end_addr = pmd_addr_end(addr, vma->vm_end); >>>> max_nr = (end_addr - addr) >> PAGE_SHIFT; >>>> >>>> - /* We only support lazyfree batching for now ... */ >>>> - if (!folio_test_anon(folio) || folio_test_swapbacked(folio)) >>>> + /* We only support lazyfree or file folios batching for now ... */ >>>> + if (folio_test_anon(folio) && folio_test_swapbacked(folio)) >>> >>> Why is it now ok to support file-backed batched unmapping when it wasn't in >>> Barry's series (see [0])? You don't seem to be justifying this? >> >> Barry's series[0] is merely aimed at optimizing lazyfree anonymous large >> folios and does not continue to optimize anonymous large folios or >> file-backed large folios at that point. > > Yep. At that time, I didn’t have an Android machine with a filesystem > that supported large folios, so I focused on lazyfree. But I > agree that lazyfree anon folios and file folios are quite > similar. > >> >> Subsequently, Barry sent out a new patch (see [1]) to optimize anonymous >> large folios. As for file-backed large folios, the batched unmapping >> support is relatively simple, since we only need to clear the PTE >> entries for file-backed large folios. > > Yep. It is actually quite straightforward to go from lazyfree > anon folios to file folios. Swap-backed anon folios are much > more tricky, though. Agree. Thanks Barry for reviewing and confirming.