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b=jKDCpqxrnNtPb3D6338CB7uyKFGcRN9WGPbj3Df0XsYjlUo8y+qkSy8lcqNPNeJxg drm0UKWmmE5vcbRMPvNbrbH28B4MgKh2k1A+SW91COElH+SNM9gBOGY0AHR2PEIO/0 uXt+OsBA3Gjbv/u2A5d4t9bWpHnLe4aMDrBEV9iWTJylLVIIEISk/J8v8ASFJf4kZe hof3guPEvNve21kEJ8h5hDC/B2BIM1/dUWtYxiMJv5Fwg08HB9R1T9Y6wk8TCOFmez SWqZglHXOb8AfaGhHDznRI1zByLsENoS99NFWM1+6DUtuJd9JKHfeVOzHK7aBmAcbP KC5lPlEjnq1MQ== From: Pratyush Yadav To: Alexander Graf , Mike Rapoport , Changyuan Lyu , Andrew Morton , Baoquan He , Pratyush Yadav , Pasha Tatashin , Jason Gunthorpe , Chris Li , Jason Miu Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org Subject: [PATCH v2 1/2] kho: move sanity checks to kho_restore_page() Date: Wed, 17 Sep 2025 14:56:53 +0200 Message-ID: <20250917125725.665-1-pratyush@kernel.org> X-Mailer: git-send-email 2.51.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 90106180003 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: uk5enpb5bkaq6atq7s7ttcn6r3tbs4nb X-HE-Tag: 1758113858-718426 X-HE-Meta: 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 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: While KHO exposes folio as the primitive externally, internally its restoration machinery operates on pages. This can be seen with kho_restore_folio() for example. It performs some sanity checks and hands it over to kho_restore_page() to do the heavy lifting of page restoration. After the work done by kho_restore_page(), kho_restore_folio() only converts the head page to folio and returns it. Similarly, deserialize_bitmap() operates on the head page directly to store the order. Move the sanity checks for valid phys and order from the public-facing kho_restore_folio() to the private-facing kho_restore_page(). This makes the boundary between page and folio clearer from KHO's perspective. While at it, drop the comment above kho_restore_page(). The comment is misleading now. The function stopped looking like free_reserved_page() since 12b9a2c05d1b4 ("kho: initialize tail pages for higher order folios properly"), and now looks even more different. Signed-off-by: Pratyush Yadav --- Notes: Changes in v2: - New in v2. kernel/kexec_handover.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index ecd1ac210dbd7..69cab82abaaef 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -183,10 +183,18 @@ static int __kho_preserve_order(struct kho_mem_track *track, unsigned long pfn, return 0; } -/* almost as free_reserved_page(), just don't free the page */ -static void kho_restore_page(struct page *page, unsigned int order) +static struct page *kho_restore_page(phys_addr_t phys) { - unsigned int nr_pages = (1 << order); + struct page *page = pfn_to_online_page(PHYS_PFN(phys)); + unsigned int nr_pages, order; + + if (!page) + return NULL; + + order = page->private; + if (order > MAX_PAGE_ORDER) + return NULL; + nr_pages = (1 << order); /* Head page gets refcount of 1. */ set_page_count(page, 1); @@ -199,6 +207,7 @@ static void kho_restore_page(struct page *page, unsigned int order) prep_compound_page(page, order); adjust_managed_page_count(page, nr_pages); + return page; } /** @@ -209,18 +218,9 @@ static void kho_restore_page(struct page *page, unsigned int order) */ struct folio *kho_restore_folio(phys_addr_t phys) { - struct page *page = pfn_to_online_page(PHYS_PFN(phys)); - unsigned long order; - - if (!page) - return NULL; - - order = page->private; - if (order > MAX_PAGE_ORDER) - return NULL; + struct page *page = kho_restore_page(phys); - kho_restore_page(page, order); - return page_folio(page); + return page ? page_folio(page) : NULL; } EXPORT_SYMBOL_GPL(kho_restore_folio); -- 2.47.3