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De Francesco" , Luis Chamberlain Subject: [PATCH v2 2/2] mm: Add folio_map_local() Date: Tue, 1 Nov 2022 20:18:28 +0000 Message-Id: <20221101201828.1170455-3-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20221101201828.1170455-1-willy@infradead.org> References: <20221101201828.1170455-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=nQV2BbG4; spf=none (imf09.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667333911; a=rsa-sha256; cv=none; b=BAJ5atOlxQFgyQINDfLJWulgrgrhiMBoJ5HOMYZCo5p6BEOyW8tfvUEdU9jj9VYCbsgKii LYU512HFeKkDnat5fReWsRSubmS5IunbMt827gopUb0++tvIBkYkapqFsxyYYqAsFFMrcB 00Ekg7dFBa5hp195JgAbt4Ecv753rR0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667333911; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=LAbynVx7FMpy2SHEr2MnqNJCSXJegM+g7qTkiXTDbYs=; b=oQ6jg2BBwudzj6Il+MFGac6WwvXxYKEQAYTdpfNUTrlGcbqYsHwyCRMhRyL4jAMAoy6oqA KrMw2J3STuF2mWPs4/rLiQpp7N47i3Ff9SkDkQDM2OMm6Faa4O2LJ77C543VI2Ld+7tmNn peBwH0gy/draW+SF8aJRNQyhgX4GkTQ= X-Stat-Signature: x34hkjk4kirht81k9snk4a6ktnu96yhu X-Rspamd-Queue-Id: C4F4E140014 Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=nQV2BbG4; spf=none (imf09.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1667333911-120467 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: Some filesystems benefit from being able to map the entire folio. On 32-bit platforms with HIGHMEM, we fall back to using vmap, which will be slow. If it proves to be a performance problem, we can look at optimising it in a number of ways. Signed-off-by: Matthew Wilcox (Oracle) --- include/linux/highmem.h | 40 ++++++++++++++++++++++++++++++++++++++++ include/linux/vmalloc.h | 6 ++++-- mm/vmalloc.c | 32 ++++++++++++++++++++++++++++++++ 3 files changed, 76 insertions(+), 2 deletions(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index e9912da5441b..d56ae62db252 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -10,6 +10,7 @@ #include #include #include +#include #include "highmem-internal.h" @@ -132,6 +133,45 @@ static inline void *kmap_local_page(struct page *page); */ static inline void *kmap_local_folio(struct folio *folio, size_t offset); +/** + * folio_map_local - Map an entire folio. + * @folio: The folio to map. + * + * Unlike kmap_local_folio(), map an entire folio. This should be undone + * with folio_unmap_local(). The address returned should be treated as + * stack-based, and local to this CPU, like kmap_local_folio(). + * + * Context: May allocate memory using GFP_KERNEL if it takes the vmap path. + * Return: A kernel virtual address which can be used to access the folio, + * or NULL if the mapping fails. + */ +static inline __must_check void *folio_map_local(struct folio *folio) +{ + might_alloc(GFP_KERNEL); + + if (!IS_ENABLED(CONFIG_HIGHMEM)) + return folio_address(folio); + if (folio_test_large(folio)) + return vm_map_folio(folio); + return kmap_local_page(&folio->page); +} + +/** + * folio_unmap_local - Unmap an entire folio. + * @addr: Address returned from folio_map_local() + * + * Undo the result of a previous call to folio_map_local(). + */ +static inline void folio_unmap_local(const void *addr, unsigned long nr_pages) +{ + if (!IS_ENABLED(CONFIG_HIGHMEM)) + return; + if (is_vmalloc_addr(addr)) + vm_unmap_ram(addr, nr_pages); + else + kunmap_local(addr); +} + /** * kmap_atomic - Atomically map a page for temporary usage - Deprecated! * @page: Pointer to the page to be mapped diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 096d48aa3437..4bb34c939c01 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -13,6 +13,7 @@ #include struct vm_area_struct; /* vma defining user mapping in mm_types.h */ +struct folio; /* also mm_types.h */ struct notifier_block; /* in notifier.h */ /* bits in flags of vmalloc's vm_struct below */ @@ -163,8 +164,9 @@ extern void *vcalloc(size_t n, size_t size) __alloc_size(1, 2); extern void vfree(const void *addr); extern void vfree_atomic(const void *addr); -extern void *vmap(struct page **pages, unsigned int count, - unsigned long flags, pgprot_t prot); +void *vmap(struct page **pages, unsigned int count, unsigned long flags, + pgprot_t prot); +void *vm_map_folio(struct folio *folio); void *vmap_pfn(unsigned long *pfns, unsigned int count, pgprot_t prot); extern void vunmap(const void *addr); diff --git a/mm/vmalloc.c b/mm/vmalloc.c index dcab1d3cf185..c101b09d15d3 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2288,6 +2288,38 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node) } EXPORT_SYMBOL(vm_map_ram); +#ifdef CONFIG_HIGHMEM +/** + * vm_map_folio() - Map an entire folio into virtually contiguous space. + * @folio: The folio to map. + * + * Maps all pages in @folio into contiguous kernel virtual space. This + * function is only available in HIGHMEM builds; for !HIGHMEM, use + * folio_address(). The pages are mapped with PAGE_KERNEL permissions. + * + * Return: The address of the area or %NULL on failure + */ +void *vm_map_folio(struct folio *folio) +{ + size_t size = folio_size(folio); + void *mem = vmap_alloc(size, NUMA_NO_NODE); + unsigned long addr = (unsigned long)mem; + + if (vmap_range_noflush(addr, addr + size, + folio_pfn(folio) << PAGE_SHIFT, + PAGE_KERNEL, folio_shift(folio))) { + vm_unmap_ram(mem, folio_nr_pages(folio)); + return NULL; + } + flush_cache_vmap(addr, addr + size); + + mem = kasan_unpoison_vmalloc(mem, size, KASAN_VMALLOC_PROT_NORMAL); + + return mem; +} +EXPORT_SYMBOL(vm_map_folio); +#endif + static struct vm_struct *vmlist __initdata; static inline unsigned int vm_area_page_order(struct vm_struct *vm) -- 2.35.1