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b=U95IUwGovyaV4WQGXtl+G6UkvlVb960QvwpE4JZMSqSKC/EmPueDdrNH1Zskgl8QA qdMBXnqGD2OxQjXfv7d8XKFoGkfEDDk0EQvI/jLcIKrGtHk+kYzWd6uSKVXiaSkc8Z /ErB3LMM8N0Y3stn0AuqhrF09FR/KKyvDwRC1DLBmq2cD7rJeo5zWRsl12s4oJtSFU eeq+dbqN0qBu4GLManypD7a2xQotcf6rWY2X3XLCYiVrOiCx5Lf2e7yAmfq0UNKkv1 HCMlAKUls4pwgfVKzANgX15rxDLnLe29ej9jvRX6fYPHGWogAJnN4BKIfUyWinsgXK WoqkgHSEd2FUg== Message-ID: <004bdc87-8c8e-44f8-93c3-1ae0a47051a9@kernel.org> Date: Thu, 30 Jul 2026 10:33:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-unstable v1 2/3] mm/migrate.c: Prevent folio splitting from interacting with KSM To: Nico Pache Cc: Usama Arif , Zi Yan , ljs@kernel.org, xu.xin16@zte.com.cn, linux-kernel@vger.kernel.org, linux-mm@kvack.org, usamaarif642@gmail.com, yuzhao@google.com, aarcange@redhat.com, akpm@linux-foundation.org, chengming.zhou@linux.dev, baolin.wang@linux.alibaba.com, liam@infradead.org, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com References: <18102ABA-0D8E-4DA0-AC30-544E34E445D5@nvidia.com> <20260609172719.803537-1-usama.arif@linux.dev> <0b268070-95d2-45bd-aea3-56cefe01dc8c@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 0A7AA180008 X-Stat-Signature: ygaxhzxgtq4qe45eqs3setckopq1tuc3 X-HE-Tag: 1785400436-526653 X-HE-Meta: U2FsdGVkX19R/SiYKnyNsGPOOvEJgF5Z8sEDABongQsHG/lpbC0Agns40Kz7SwqSACHnKVTtHpSGLkF9YcxdsNaPD86odnrHIgEc2QWoPD5tR8cOU5wN5Ccwo715e5hCzEAnJ06yOOqMB5AWDPS53L0xJlvM7JWyUT51bWRXvAsFrjhHXUHM2uHYler4H3rO0UBFLKAkg02NbEfKwWxmgJFzVhzqT04Eirs2oP5PHDFx3yYD/WvDD1Cu7XfAumNtMkMr4BL+P7+OtCGFWK3LPwJuX6JSl6AnBeBVI2qip/cDsHX1asfSN3mmdo3txxjsotOy1zcvF27tbicrANl7denypm0LolctFNeBqs3oXHkOKJwkhRQrA33ulZwvFdmhEkdvVVisOQX1PbmXbxRXmKXxbeFSthlqp/ZD7+U2Qnoz6KqVmgPRXNEzouyMjac6+XhqK4b4FcYJ+Dz4SxngECSxPrDC1/dSfCT2HBbkk+BYUVQuVgURMYeW3beB65wJETOYBmAfYn88nBqgeiPdX9f+SGIEh8kBxl9rnmdrYO622kwnueWG02eku+nOTtl5zB3I/ZE4EC5L3iYCYxDjw72sbAP1GpKJBqzVuofyOVAIpRBAfli5EI73u/NYJpL4F1xMhHEyyo5SiA+R8a8b8uVToHXmmejZc4d4AOOwVfK1QyLO+TxOGUDyxGA6Q9gvxCtERHRTblJy8VG5vnBApkhVWup412HsKZme1EJCRfqAfkk6ii8JzUjyIdEAYlL6fQxaK8lZX6K6lw6CqyjdQfMQIAX/GnXkyfxPAaVIgiq4RQVX9QWxvqQF/IAc3A6ZSuwHRDtaReOesT6s11V29AqVkhkFczkjWkCAfQGsz/1TpG4iyxrmTO1lb0vhurxc4FQ00EBxh0VaoWU9IcKMx0zxdVeRr7tBqlEFr3fZrgSoxd/r3xqdQsUanG1ddcobVj4h8RO6MfUm/tgLiGK UZLsUYlr tqKA7gNeHMIwtEBwb2X9I2IwNOHToVQop3d5PjtaeVtZMUJQIma8jWyXnMF5fYmL9gCKID0v01OsgmVy5KG6PrExFFz1+qS/wviyVj3yd8sr+4WtcyfH004LNm6iDlV5IP1JTtVseFkyC7/ilQIgsZZr8r08CjAda6gKq7PE+3qo2B100XAsj6uFSjuAcoykyR0iyP4RHXezUs/L/bTA56/OouzHtWmL/Pja1eSqx4ixelFvAgJm2UF7kyFVTGj2XB6qE3No3t6Sk7YW/o+vjiqf86yPkHHBn1ZCREqP69W+Qknrxv9adLqwBvObqABo6ZsOVGfWITGX+qJjpHLrxdl/mPtxrkwX5zcRjFmGwT1jKSiqzSmL8f11uXR/NscYo79TD Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/29/26 18:54, Nico Pache wrote: > On Tue, Jul 21, 2026 at 8:02 AM David Hildenbrand (Arm) > wrote: >> >> On 7/20/26 17:28, Nico Pache wrote: >>> On Wed, Jul 15, 2026 at 3:30 AM David Hildenbrand (Arm) >>> wrote: >>> >>> this series (v1) would be "dont scan VM_MERGEABLE entries when KSM is running" >>> >>> It stops all VM_MEREABLE entries from being candidates, while the V2 I >>> would like to propose goes back to my RFC's alternative solution >>> a ) "skip zeropage remapping if the split comes from KSM" >>> >>> I think (a) is better than V1 as it doesnt indiscriminately target all >>> VM_MERGEABLE mapping but rather those that are triggering the issue >>> (the split). >> >> Not sure. There could be anything else in the system triggering the split before >> KSM comes around. >> >> So v1 just cleanly separates them, independent who triggers the split. > > Yes but now all VM_MERGEABLEs lose the underutilized shrinker > independent from weather KSM was the one who triggered it. Because KSM takes care of it? What am I missing? -- Cheers, David