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b=I9OEVz4rylaFp3pNevk2zHSWkGG2xI2nyzD4N+VrsqzLiK1w7rxT6CEqu8obDWZrV ir563Os2LvTO+r32bkhjQy5lRULt4Un5DdFFZymuxhsfWbK+SpHm91nfvdIPDUjoDX LrVn3eYMXPMVQ4ezEpXf3grANdI58bDPZA6kzFBX2aiEPELH2AXKLEHljNlWdgTyVo 0SWGPlHjjXiahVuTpvmWHoMprGDGx/DDHMqOmHQ/1AZeCrbT/i8XS+KHZYkAgaAEte R1bjzdWSobiftdLUC67botuwZLso+80sTGQkFhfiv1NgGalqM+THxadGthdkCcLHn6 +Pvw+93fVg6gQ== Message-ID: <0867dac0-bc48-4aa9-891f-2066a3eff989@kernel.org> Date: Wed, 3 Jun 2026 01:07:39 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/15] mm: introduce ANON_VMA_LAZY for deferred anon_vma creation To: tao , catalin.marinas@arm.com, will@kernel.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, akpm@linux-foundation.org, david@kernel.org, willy@infradead.org, sj@kernel.org, kees@kernel.org, luizcap@redhat.com, zhangjiao2@cmss.chinamobile.com, kas@kernel.org, ljs@kernel.org Cc: hpa@zytor.com, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, jack@suse.cz, riel@surriel.com, jannh@google.com, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, nao.horiguchi@gmail.com, 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, pfalcato@suse.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, damon@lists.linux.dev, shakeel.butt@linux.dev, ryncsn@gmail.com, 21cnbao@gmail.com, jparsana@google.com, dvander@google.com, zhangji1@honor.com, wangzicheng@honor.com References: <20260527110147.17815-1-tao.wangtao@honor.com> Content-Language: en-US From: Harry Yoo In-Reply-To: <20260527110147.17815-1-tao.wangtao@honor.com> Content-Type: multipart/signed; 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boundary="------------YusAIRMqlR7LLXeBVYeRGebJ"; protected-headers="v1" From: Harry Yoo To: tao , catalin.marinas@arm.com, will@kernel.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, akpm@linux-foundation.org, david@kernel.org, willy@infradead.org, sj@kernel.org, kees@kernel.org, luizcap@redhat.com, zhangjiao2@cmss.chinamobile.com, kas@kernel.org, ljs@kernel.org Cc: hpa@zytor.com, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, jack@suse.cz, riel@surriel.com, jannh@google.com, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, nao.horiguchi@gmail.com, 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, pfalcato@suse.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, damon@lists.linux.dev, shakeel.butt@linux.dev, ryncsn@gmail.com, 21cnbao@gmail.com, jparsana@google.com, dvander@google.com, zhangji1@honor.com, wangzicheng@honor.com Message-ID: <0867dac0-bc48-4aa9-891f-2066a3eff989@kernel.org> Subject: Re: [PATCH 0/15] mm: introduce ANON_VMA_LAZY for deferred anon_vma creation References: <20260527110147.17815-1-tao.wangtao@honor.com> In-Reply-To: <20260527110147.17815-1-tao.wangtao@honor.com> --------------YusAIRMqlR7LLXeBVYeRGebJ Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 5/27/26 8:01 PM, tao wrote: > Design overview > --------------- >=20 > ANON_VMA_LAZY defers anon_vma allocation until it is actually needed > (for example during fork). VMAs that never participate in sharing can > avoid creating anon_vma structures entirely. >=20 > Before an anon_vma exists, rmap operations rely directly on VMA > information, so no anon_vma locking is required. An anon_vma is created= > and linked only when sharing semantics are required. It is unfortunate that the design overview doesn't cover correctness aspect at all. VMAs are subject to change (even before being shared with other processes), and rmap needs something that doesn't go away across VMA merging, split, etc. I'm not sure how the idea is supposed work correctly. --=20 Cheers, Harry / Hyeonggon --------------YusAIRMqlR7LLXeBVYeRGebJ-- --------------ey4l15FF9oEWH3xFySCAaCAx Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQQQ1ub6gR5ogjaKRmOGXBN6rc5S1gUCah7/ywAKCRCGXBN6rc5S 1otsAP9nwP515uUxVeg/W2YVm5teA1//l+vahNQqqxIcs095VAD+Jy2ls4/NwtfN KAQR7h3eWnaTbpGNQamLViiFJG7giQ8= =rhvK -----END PGP SIGNATURE----- --------------ey4l15FF9oEWH3xFySCAaCAx--