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b=BbSL0S09gbjTOCH902eTaZWwFJxiLeFTOOB0ffYmk4eaCstJylLTx1t5vmQfw3sMW FBMRq8KlvWpL9RknySCg/Y492McoR4jYgskaAyrGVYHIrcZ4eeFSNn0aQ8ypCGvgjG lfg23tUFLhNdRJPXoTIUvDcwRh7KGTg/AsFBUXhM5zjomrWRfW4QWxwHpitwcXKeIA jb4nm4inocCahiqGBS1wWaxnbzyMsjezBAX9clB6/D/XBeTHLT05CRFBfMgFru8tTx WJiNRL4QO4VaqozpqEW6+ho4h+ACObKTjF3olxl/LyBzntH1TbNdMMD7mNhDBvQ6Fz 8YUWugdygI+SA== Message-ID: Date: Fri, 20 Mar 2026 12:41:00 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm: migrate: requeue destination folio on deferred split queue To: Andrew Morton , SeongJae Park Cc: Usama Arif , npache@redhat.com, ziy@nvidia.com, willy@infradead.org, linux-mm@kvack.org, matthew.brost@intel.com, joshua.hahnjy@gmail.com, hannes@cmpxchg.org, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, linux-kernel@vger.kernel.org, kernel-team@meta.com, richard.weiyang@gmail.com, stable@vger.kernel.org References: <20260314154042.327ba957b1a8c10f64ae0169@linux-foundation.org> <20260315000555.76876-1-sj@kernel.org> <20260314172321.3ca062bb70e51fefa633a6fe@linux-foundation.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 4F4A44000C X-Rspamd-Server: rspam08 X-Stat-Signature: d17q66zmsifkoodjx496qat3i1oj3xh7 X-HE-Tag: 1774006868-153416 X-HE-Meta: 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 AR0LURRU pvZriM/B3UEG+Kv+YxqKpBopahUHxAoIBwWh4pogwfpEe03sWjB0AQ/8sV9JJhcKNhLnaMHVehz/ae+4R0qVEAQAYweU8a86uLVJt/zDE3GZNrHa5Xe67UZVre0rPdk7juUHWPqh6C7mrJ+o8AT3n7shZxbEwItxhIIV8wTB8ZCaxRYK6VnklNkXssIbluGU6Kez//cimSniBlp87S8d3PVUVVIeul1O5XOVyUKVO6+4lysziaBBpPujfO7Y0uJVpCAn7u0h+2ZkKjPnGmPDLbK9Tj+S4NnTndKJLUlHdhLhNlRWaATf6wzcesAp5aScUHajLu7+rf0MYVMa9eYztXZQQTjfP+NShr3+o Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/15/26 01:23, Andrew Morton wrote: > On Sat, 14 Mar 2026 17:05:54 -0700 SeongJae Park wrote: > >> Because THPs are >> removed from the deferred_list, THP shinker cannot split the underutilized THPs >> in time. As a result, users will show less free memory than before. > > That'll do, thanks ;) > > Pasted, added cc:stable. It's been there since 6.12 so I don't see a > need to rush this in, so I won't move this into mm-hotfixes - it'll go > into mainline for 7.1-rc1 after which -stable should pick it up. Makes sense. I guess using the partially-mapped is only a slight problem, because we usually try to split partially-mapped before migrating. So it's mostly about over-allocated THPs (mostly 0) not getting scanned and split+reclaimed after they were migrated. Under memory pressure without swap, that might create a user-visible problem, especially when many such THPs are migrated before being scanned for zeropages that can be reclaimed. -- Cheers, David