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De Francesco" , Luis Chamberlain , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Uladzislau Rezki Subject: [RFC] vmap_folio() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660860413; a=rsa-sha256; cv=none; b=gRntKNTgUuKT8n3IMGaEKeDhpCDHfT5ZAsQEcSFDBq/Unu38JR3lF+Bl9XjM6OAKQZ/Pdv 4kfDJqHebSt4AKPbMrL2cHzfAu6X3fIO3XaaQ17Jt248CQNVp3KYLCsyLT4OfEgWWaDfws Uf3ULubuOpX666oaFt9qwyLKCQYxcy4= ARC-Authentication-Results: i=1; imf31.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=vWKNgjak; dmarc=none; spf=none (imf31.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660860413; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=E4wpWtZzYIevzpBbBnTerCEmxL2Wh7527eJL2rvGkAg=; b=2z2QhBZ9sUSFAXFmPgFvbb7idqWosZJJMTOkyD0X1t3m6Ptc7JtizZc6ALpBsN6w+Vbx9T A1SyJTJzk4cqmj8F5nozoQ/5EZ+OG+wQpaLQiz8LKPaFVBZDUlCcw/8QPAYLgQs/wrdJjy GkMmNmZhDM+0t/+K63R5gGo7jSY2W3I= X-Rspamd-Server: rspam06 X-Rspam-User: X-Stat-Signature: 44fzzyqyc1u4bmnqtmpw5bt6guan5py9 Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=vWKNgjak; dmarc=none; spf=none (imf31.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspamd-Queue-Id: 2CC5C28107 X-HE-Tag: 1660860410-73694 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: On Tue, Aug 16, 2022 at 07:08:22PM +0100, Matthew Wilcox wrote: > For these reasons, I proposing the logical equivalent to this: > > +void *folio_map_local(struct folio *folio) > +{ > + if (!IS_ENABLED(CONFIG_HIGHMEM)) > + return folio_address(folio); > + if (!folio_test_large(folio)) > + return kmap_local_page(&folio->page); > + return vmap_folio(folio); > +} > > (where vmap_folio() is a new function that works a lot like vmap(), > chunks of this get moved out-of-line, etc, etc., but this concept) This vmap_folio() compiles but is otherwise untested. Anything I obviously got wrong here? diff --git a/mm/vmalloc.c b/mm/vmalloc.c index dd6cdb201195..1867759c33ff 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2848,6 +2848,42 @@ void *vmap(struct page **pages, unsigned int count, } EXPORT_SYMBOL(vmap); +#ifdef CONFIG_HIGHMEM +/** + * vmap_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 *vmap_folio(struct folio *folio) +{ + size_t size = folio_size(folio); + struct vm_struct *area; + unsigned long addr; + + might_sleep(); + + area = get_vm_area_caller(size, VM_MAP, __builtin_return_address(0)); + if (!area) + return NULL; + + addr = (unsigned long)area->addr; + if (vmap_range_noflush(addr, addr + size, + folio_pfn(folio) << PAGE_SHIFT, + PAGE_KERNEL, folio_shift(folio))) { + vunmap(area->addr); + return NULL; + } + flush_cache_vmap(addr, addr + size); + + return area->addr; +} +#endif + #ifdef CONFIG_VMAP_PFN struct vmap_pfn_data { unsigned long *pfns;