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 654062153E0 for ; Mon, 17 Mar 2025 05:11:07 +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=1742188267; cv=none; b=JHXt7ISWGHU4fL2IqzSfF8f1LzwDgBjQn8avCSRYCpv1BjeSfpa27QS5pCabwKTxP7y/Lu+zveEslP8nyEz81Z1uRKn/+WLLALn8d1pO206rv7+ON8hkZ0L4e/mPSisvXslTJc7rPlawJBTrp90S6dtzU7EWzL9mNVMz78tzr6c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742188267; c=relaxed/simple; bh=sSmr/q0qKQreVxes2MeVjWQ7Okv7ecDDw4VeCm/sgSk=; h=Date:To:From:Subject:Message-Id; b=Wj62PwLdCHu96uji1rAIlkxKp7QZv9e4cm8wHfIPGr8p4z56gkb9wSec+IbUZXlvY9F6EogFffEKlyydvmmZ2YUJqo611Qwq/4/aiWx5vqbRrYzw1BNW0Tq4xR5RI1jo4eKA/QUnVQkwQ2xo8w1n+TpFdMZS8y5bBCsaKvNQuCY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=JdKMJjqQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="JdKMJjqQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D09C1C4CEEC; Mon, 17 Mar 2025 05:11:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1742188266; bh=sSmr/q0qKQreVxes2MeVjWQ7Okv7ecDDw4VeCm/sgSk=; h=Date:To:From:Subject:From; b=JdKMJjqQDOpYBkY8TfZCySI1zY9bbfJm81Z/Vfv73jh47PzrLdqTP7ep6aQTCtjCB kS2SvugSOlWSKq0j6THRQMUAHSOoGKsGcLlQqs7WHB1GtqBnwmr/IC6PiWCDLGW2gt x9ZTIEm9eo5LQbTIweeRRQAebJ0VrFIpzqTfNpM4= Date: Sun, 16 Mar 2025 22:11:06 -0700 To: mm-commits@vger.kernel.org,willy@infradead.org,tzimmermann@suse.de,soci@c64.rulez.org,simona.vetter@ffwll.ch,mcanal@igalia.com,jayakumar.lkml@gmail.com,deller@gmx.de,david@redhat.com,lorenzo.stoakes@oracle.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-provide-mapping_wrprotect_range-function.patch removed from -mm tree Message-Id: <20250317051106.D09C1C4CEEC@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: provide mapping_wrprotect_range() function has been removed from the -mm tree. Its filename was mm-provide-mapping_wrprotect_range-function.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Lorenzo Stoakes Subject: mm: provide mapping_wrprotect_range() function Date: Sat, 8 Feb 2025 15:52:55 +0000 In the fb_defio video driver, page dirty state is used to determine when frame buffer pages have been changed, allowing for batched, deferred I/O to be performed for efficiency. This implementation had only one means of doing so effectively - the use of the folio_mkclean() function. However, this use of the function is inappropriate, as the fb_defio implementation allocates kernel memory to back the framebuffer, and then is forced to specified page->index, mapping fields in order to permit the folio_mkclean() rmap traversal to proceed correctly. It is not correct to specify these fields on kernel-allocated memory, and moreover since these are not folios, page->index, mapping are deprecated fields, soon to be removed. We therefore need to provide a means by which we can correctly traverse the reverse mapping and write-protect mappings for a page backing an address_space page cache object at a given offset. This patch provides this - mapping_wrprotect_range() - which allows for this operation to be performed for a specified address_space, offset, PFN and size, without requiring a folio nor, of course, an inappropriate use of page->index, mapping. With this provided, we can subsequently adjust the fb_defio implementation to make use of this function and avoid incorrect invocation of folio_mkclean() and more importantly, incorrect manipulation of page->index and mapping fields. Link: https://lkml.kernel.org/r/e5bf969d64e7f2f2ae944d42341fc8994b736a81.1739029358.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Cc: David Hildenbrand Cc: Helge Deller Cc: Jaya Kumar Cc: Kajtar Zsolt Cc: Maíra Canal Cc: Matthew Wilcox Cc: Simona Vetter Cc: Thomas Zimemrmann Signed-off-by: Andrew Morton --- include/linux/rmap.h | 3 + mm/rmap.c | 74 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 77 insertions(+) --- a/include/linux/rmap.h~mm-provide-mapping_wrprotect_range-function +++ a/include/linux/rmap.h @@ -738,6 +738,9 @@ unsigned long page_address_in_vma(const */ int folio_mkclean(struct folio *); +int mapping_wrprotect_range(struct address_space *mapping, pgoff_t pgoff, + unsigned long pfn, unsigned long nr_pages); + int pfn_mkclean_range(unsigned long pfn, unsigned long nr_pages, pgoff_t pgoff, struct vm_area_struct *vma); --- a/mm/rmap.c~mm-provide-mapping_wrprotect_range-function +++ a/mm/rmap.c @@ -1135,6 +1135,80 @@ int folio_mkclean(struct folio *folio) } EXPORT_SYMBOL_GPL(folio_mkclean); +struct wrprotect_file_state { + int cleaned; + pgoff_t pgoff; + unsigned long pfn; + unsigned long nr_pages; +}; + +static bool mapping_wrprotect_range_one(struct folio *folio, + struct vm_area_struct *vma, unsigned long address, void *arg) +{ + struct wrprotect_file_state *state = (struct wrprotect_file_state *)arg; + struct page_vma_mapped_walk pvmw = { + .pfn = state->pfn, + .nr_pages = state->nr_pages, + .pgoff = state->pgoff, + .vma = vma, + .address = address, + .flags = PVMW_SYNC, + }; + + state->cleaned += page_vma_mkclean_one(&pvmw); + + return true; +} + +static void __rmap_walk_file(struct folio *folio, struct address_space *mapping, + pgoff_t pgoff_start, unsigned long nr_pages, + struct rmap_walk_control *rwc, bool locked); + +/** + * mapping_wrprotect_range() - Write-protect all mappings in a specified range. + * + * @mapping: The mapping whose reverse mapping should be traversed. + * @pgoff: The page offset at which @pfn is mapped within @mapping. + * @pfn: The PFN of the page mapped in @mapping at @pgoff. + * @nr_pages: The number of physically contiguous base pages spanned. + * + * Traverses the reverse mapping, finding all VMAs which contain a shared + * mapping of the pages in the specified range in @mapping, and write-protects + * them (that is, updates the page tables to mark the mappings read-only such + * that a write protection fault arises when the mappings are written to). + * + * The @pfn value need not refer to a folio, but rather can reference a kernel + * allocation which is mapped into userland. We therefore do not require that + * the page maps to a folio with a valid mapping or index field, rather the + * caller specifies these in @mapping and @pgoff. + * + * Return: the number of write-protected PTEs, or an error. + */ +int mapping_wrprotect_range(struct address_space *mapping, pgoff_t pgoff, + unsigned long pfn, unsigned long nr_pages) +{ + struct wrprotect_file_state state = { + .cleaned = 0, + .pgoff = pgoff, + .pfn = pfn, + .nr_pages = nr_pages, + }; + struct rmap_walk_control rwc = { + .arg = (void *)&state, + .rmap_one = mapping_wrprotect_range_one, + .invalid_vma = invalid_mkclean_vma, + }; + + if (!mapping) + return 0; + + __rmap_walk_file(/* folio = */NULL, mapping, pgoff, nr_pages, &rwc, + /* locked = */false); + + return state.cleaned; +} +EXPORT_SYMBOL_GPL(mapping_wrprotect_range); + /** * pfn_mkclean_range - Cleans the PTEs (including PMDs) mapped with range of * [@pfn, @pfn + @nr_pages) at the specific offset (@pgoff) _ Patches currently in -mm which might be from lorenzo.stoakes@oracle.com are mm-mremap-correctly-handle-partial-mremap-of-vma-starting-at-0.patch mm-mremap-refactor-mremap-system-call-implementation.patch mm-mremap-introduce-and-use-vma_remap_struct-threaded-state.patch mm-mremap-initial-refactor-of-move_vma.patch mm-mremap-complete-refactor-of-move_vma.patch mm-mremap-refactor-move_page_tables-abstracting-state.patch mm-mremap-thread-state-through-move-page-table-operation.patch