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b=GSvVnMTCcRhkxqlqeDx3rM6srCHZuDenv1DdtPoFP9SUQF8TtuPX/r+4ffLF35a1z Ya3vXMuTz4OOJrBpC3QVOcQytVqQMUT1mJ5GxbGIGf7EJGU+N6gJF9KKyPHkdhuied j04tYZXUUvXAkbj2ysXMysEc59RfXPQGZHhTSA6i6PI4+j57T7VPUOH69hOp+j/cy2 yVhWELbxXuWm5SP2qxoGok6mGdD2AiEEDOTR9oIxhwob/7H52+k1jLuQMGzMgKqnNt u8PlegUm+gteaVi/n5UohU/uGYeeR/8vQpstamEQl+CsHkiUMRiikbcO/+Ojwu/bls wMOHaiNU6bRzA== Message-ID: Date: Fri, 6 Feb 2026 10:42:24 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv6 13/17] hugetlb: Remove VMEMMAP_SYNCHRONIZE_RCU To: Kiryl Shutsemau , Andrew Morton , Muchun Song , Matthew Wilcox , Usama Arif , Frank van der Linden Cc: Oscar Salvador , Mike Rapoport , Vlastimil Babka , Lorenzo Stoakes , Zi Yan , Baoquan He , Michal Hocko , Johannes Weiner , Jonathan Corbet , Huacai Chen , WANG Xuerui , Palmer Dabbelt , Paul Walmsley , Albert Ou , Alexandre Ghiti , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org References: <20260202155634.650837-1-kas@kernel.org> <20260202155634.650837-14-kas@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 839EE140009 X-Stat-Signature: aouxa5mqegeed5wco76nn3g1bb3mkd4i X-Rspam-User: X-HE-Tag: 1770370953-63962 X-HE-Meta: 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 exUidbbI 46wQolO07LGf22IR2HGqqBXVx7y5/PylV2gm//LYmDrxtP8lDXbATbDHPANUGGtlSuL/tOdcH9+o9L6jyvSuDbVZyhZEsWkFeOVN8zAX4RB2XvSo9PNl4LBaoGtMZg67XFzhWlSwTjcodp/mnQnGYNFtCcMBr0tB8J47tubfEeRgn4lT58Xzsc4ZoS5bVKPRj2uh2/CRkJpGNdE1dC6MdTDlm6U96xp8FVVnHtyMmOz1v/biL69AJ5QKwUQP5mO9C3hG4SZrURSMAmIqyCe2PAInZ9waBVZUxQ3L+xkLNNySppch9wnP83WPmDXFb2yv0UwU3fTtY2ZNqNKM= 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 2/2/26 16:56, Kiryl Shutsemau wrote: > The VMEMMAP_SYNCHRONIZE_RCU flag triggered synchronize_rcu() calls to > prevent a race between HVO remapping and page_ref_add_unless(). The > race could occur when a speculative PFN walker tried to modify the > refcount on a struct page that was in the process of being remapped > to a fake head. > > With fake heads eliminated, page_ref_add_unless() no longer needs RCU > protection. > > Remove the flag and synchronize_rcu() calls. > > Signed-off-by: Kiryl Shutsemau > Reviewed-by: Muchun Song > --- Reviewed-by: David Hildenbrand (Arm) -- Cheers, David