From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 584681F3BA2 for ; Wed, 17 Sep 2025 12:57:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758113857; cv=none; b=o7XmfNz+8Ba1UhtbRWUyPGPh1nDx47RnBvNjNo8lTkRK4O//En1PEvwuyLWQAsVnVT2LwB48VrmP8L3UiWCpk5KrvdI6i+ee7GCwD4/0+kELtIf3VJ21CDH79Qxe6L3AsDV0Rd4bmM5MoICIGj0ZLLQExqESY18SGjL4KOr8urY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758113857; c=relaxed/simple; bh=bVQjh4jiUS12TD+kXPcBc3hIfzoE7mbPAz8+HVg3K0U=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=MxmNSi2IdFiuYU0/P/o5OjioAszhkg9RrQ3NNZhjfi4u8LpdJwFykw06Oa/YDrvpR0raKdfWGCXeNF4jqV0B3BgUWlRioHj0oCr3/xh7wZ25Mckx37jOCGbFGEyvQtL2GcQ6FaWtSyl8mt8h1JrYX3ei34UdDX2QqE+U9VKD7lw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jKDCpqxr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jKDCpqxr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CA04C4CEF0; Wed, 17 Sep 2025 12:57:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758113857; bh=bVQjh4jiUS12TD+kXPcBc3hIfzoE7mbPAz8+HVg3K0U=; h=From:To:Cc:Subject:Date:From; 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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