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b=iYIHdFRLbDb9dyt6VlP4jwIQGdzjgP4C0/I3oSr8QEKEq5jTwwRZJUrRJtOzzA3d3 ul3zgxJmUr3HgWkJ9HBsTJhVcnU6ZtPIV+vw4ytNw5WIWXRjsP8lMqQVR5eP/ZLhvg gI/eXdV6aJ9aetiEmcgNqbvi75ULz9BNpcAHx5TN+sw/9PfvzzJHmZc57gBXFB11Tf 9X9MSeHPJPU+WhI5/mPpj2wApuaADExGIrm2td5yuTzfHvXfi+U9wpB1Fm+hFe+Wmc tvEEIlVNrrB4Ss88kZIoM+FhYl4NG7IQUEtReipVIXgHjLdNh2X6kUfDrpRyr/hDsl qZ1v9M/CP76+Q== From: Pratyush Yadav To: Michal Clapinski Cc: Evangelos Petrongonas , Pasha Tatashin , Mike Rapoport , Pratyush Yadav , Alexander Graf , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: [PATCH v2] kho: add support for deferred struct page init In-Reply-To: <20260210130418.297153-1-mclapinski@google.com> (Michal Clapinski's message of "Tue, 10 Feb 2026 14:04:18 +0100") References: <20260210130418.297153-1-mclapinski@google.com> Date: Tue, 10 Feb 2026 14:55:22 +0100 Message-ID: <2vxzecmssnxx.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Queue-Id: 04361180010 X-Rspamd-Server: rspam07 X-Stat-Signature: 7zpfe8kga9rdotbj18pgm9yhik7qou8n X-HE-Tag: 1770731726-553115 X-HE-Meta: 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 //QPpHDG fiCBXdBMWb4Vl4/GKEXOIMLe4SCliA1V/rhH64mn4KXRqmISGWm2v3Uu065tjKO8qvLL/Ja4NXNgbgsxIWfVO+UDTh7TTMsN8rB9i4IuU76pqxuehexDoexIwzGHS3DefV0Q6SnxGMAn91xKkilitm8WNY30wmqWjc0ZAI4SCv5ub95zJhASPqsllnSE9UEC9jZpe9cKNnYH+QieA8xnJyQwDSg== 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 Tue, Feb 10 2026, Michal Clapinski wrote: > When `CONFIG_DEFERRED_STRUCT_PAGE_INIT` is enabled, struct page > initialization is deferred to parallel kthreads that run later > in the boot process. > > During KHO restoration, `deserialize_bitmap()` writes metadata for > each preserved memory region. However, if the struct page has not been > initialized, this write targets uninitialized memory, potentially > leading to errors like: > ``` > BUG: unable to handle page fault for address: ... > ``` > > Fix this by introducing `kho_get_preserved_page()`, which ensures > all struct pages in a preserved region are initialized by calling > `init_deferred_page()` which is a no-op when deferred init is disabled > or when the struct page is already initialized. > > Signed-off-by: Evangelos Petrongonas > Signed-off-by: Michal Clapinski Reviewed-by: Pratyush Yadav (Google) [...] -- Regards, Pratyush Yadav