From patchwork Fri Apr 10 21:33:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 11483655 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A96CD81 for ; Fri, 10 Apr 2020 21:33:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 68F1220753 for ; Fri, 10 Apr 2020 21:33:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="KLZJsFgg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 68F1220753 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3E6CD8E0072; Fri, 10 Apr 2020 17:33:04 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 3BDBA8E0067; Fri, 10 Apr 2020 17:33:04 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2FACC8E0072; Fri, 10 Apr 2020 17:33:04 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0086.hostedemail.com [216.40.44.86]) by kanga.kvack.org (Postfix) with ESMTP id 1787B8E0067 for ; Fri, 10 Apr 2020 17:33:04 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id BDDD752B7 for ; Fri, 10 Apr 2020 21:33:03 +0000 (UTC) X-FDA: 76693245846.25.snail03_37ca95acf7721 X-Spam-Summary: 20,1.5,0,f9a43ed9b69429e6,d41d8cd98f00b204,akpm@linux-foundation.org,,RULES_HIT:2:41:355:379:800:960:967:973:988:989:1260:1263:1345:1359:1381:1431:1437:1535:1605:1730:1747:1777:1792:2198:2199:2393:2525:2553:2559:2565:2682:2685:2740:2859:2890:2902:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3865:3866:3867:3870:3871:3872:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4042:4049:4118:4250:4321:4605:5007:6119:6261:6653:6737:7514:7576:7875:7903:8599:8603:9025:9545:10009:10913:11026:11473:11658:11914:12043:12048:12291:12296:12297:12438:12517:12519:12555:12679:12683:12783:12986:13161:13229:13846:21080:21324:21450:21451:21627:21795:21939:21990:30001:30003:30034:30051:30054:30070:30090,0,RBL:198.145.29.99:@linux-foundation.org:.lbl8.mailshell.net-64.100.201.201 62.2.0.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:1:0,LFtime:3,LUA_SUMMARY:none X-HE-Tag: snail03_37ca95acf7721 X-Filterd-Recvd-Size: 7802 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf41.hostedemail.com (Postfix) with ESMTP for ; Fri, 10 Apr 2020 21:33:03 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 37AF020801; Fri, 10 Apr 2020 21:33:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586554382; bh=MS//5+UYYZ6kRsxdTpD0eNl3XhVdpngVpYI6wVg4GaY=; h=Date:From:To:Subject:In-Reply-To:From; b=KLZJsFgg5iACMnsr6ftvy1FMznECDz+Y7LdpY2gjxNAx17iYRbUe2wWdwP3b0xmih HXPZ+v+pB+G0qwdcIY0pVH5q5TgIfMQNibfBXhX1Q82073MQdsxbOOguLyZrnLS2Rq z//K/Ugopx0e5FMKNi029I8RJTchybPNwgTKDChI= Date: Fri, 10 Apr 2020 14:33:01 -0700 From: Andrew Morton To: akpm@linux-foundation.org, arjunroy@google.com, davem@davemloft.net, edumazet@google.com, jgg@ziepe.ca, linux-mm@kvack.org, mm-commits@vger.kernel.org, sfr@canb.auug.org.au, soheil@google.com, torvalds@linux-foundation.org, willy@infradead.org Subject: [patch 15/35] mm/memory.c: add vm_insert_pages() Message-ID: <20200410213301.Nh4ENtuKn%akpm@linux-foundation.org> In-Reply-To: <20200410143047.bf34a933ce1affdc042c7c80@linux-foundation.org> User-Agent: s-nail v14.8.16 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: From: Arjun Roy Subject: mm/memory.c: add vm_insert_pages() Add the ability to insert multiple pages at once to a user VM with lower PTE spinlock operations. The intention of this patch-set is to reduce atomic ops for tcp zerocopy receives, which normally hits the same spinlock multiple times consecutively. [akpm@linux-foundation.org: pte_alloc() no longer takes the `addr' argument] [arjunroy@google.com: add missing page_count() check to vm_insert_pages()] Link: http://lkml.kernel.org/r/20200214005929.104481-1-arjunroy.kdev@gmail.com [arjunroy@google.com: vm_insert_pages() checks if pte_index defined] Link: http://lkml.kernel.org/r/20200228054714.204424-2-arjunroy.kdev@gmail.com Link: http://lkml.kernel.org/r/20200128025958.43490-2-arjunroy.kdev@gmail.com Signed-off-by: Arjun Roy Signed-off-by: Eric Dumazet Signed-off-by: Soheil Hassas Yeganeh Cc: David Miller Cc: Matthew Wilcox Cc: Jason Gunthorpe Cc: Stephen Rothwell Signed-off-by: Andrew Morton --- include/linux/mm.h | 2 mm/memory.c | 129 ++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 129 insertions(+), 2 deletions(-) --- a/include/linux/mm.h~mm-add-vm_insert_pages +++ a/include/linux/mm.h @@ -2689,6 +2689,8 @@ struct vm_area_struct *find_extend_vma(s int remap_pfn_range(struct vm_area_struct *, unsigned long addr, unsigned long pfn, unsigned long size, pgprot_t); int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *); +int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, + struct page **pages, unsigned long *num); int vm_map_pages(struct vm_area_struct *vma, struct page **pages, unsigned long num); int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, --- a/mm/memory.c~mm-add-vm_insert_pages +++ a/mm/memory.c @@ -1419,8 +1419,7 @@ void zap_vma_ptes(struct vm_area_struct } EXPORT_SYMBOL_GPL(zap_vma_ptes); -pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, - spinlock_t **ptl) +static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr) { pgd_t *pgd; p4d_t *p4d; @@ -1439,6 +1438,16 @@ pte_t *__get_locked_pte(struct mm_struct return NULL; VM_BUG_ON(pmd_trans_huge(*pmd)); + return pmd; +} + +pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, + spinlock_t **ptl) +{ + pmd_t *pmd = walk_to_pmd(mm, addr); + + if (!pmd) + return NULL; return pte_alloc_map_lock(mm, pmd, addr, ptl); } @@ -1491,6 +1500,122 @@ out: return retval; } +#ifdef pte_index +static int insert_page_in_batch_locked(struct mm_struct *mm, pmd_t *pmd, + unsigned long addr, struct page *page, pgprot_t prot) +{ + int err; + + if (!page_count(page)) + return -EINVAL; + err = validate_page_before_insert(page); + return err ? err : insert_page_into_pte_locked( + mm, pte_offset_map(pmd, addr), addr, page, prot); +} + +/* insert_pages() amortizes the cost of spinlock operations + * when inserting pages in a loop. Arch *must* define pte_index. + */ +static int insert_pages(struct vm_area_struct *vma, unsigned long addr, + struct page **pages, unsigned long *num, pgprot_t prot) +{ + pmd_t *pmd = NULL; + spinlock_t *pte_lock = NULL; + struct mm_struct *const mm = vma->vm_mm; + unsigned long curr_page_idx = 0; + unsigned long remaining_pages_total = *num; + unsigned long pages_to_write_in_pmd; + int ret; +more: + ret = -EFAULT; + pmd = walk_to_pmd(mm, addr); + if (!pmd) + goto out; + + pages_to_write_in_pmd = min_t(unsigned long, + remaining_pages_total, PTRS_PER_PTE - pte_index(addr)); + + /* Allocate the PTE if necessary; takes PMD lock once only. */ + ret = -ENOMEM; + if (pte_alloc(mm, pmd)) + goto out; + pte_lock = pte_lockptr(mm, pmd); + + while (pages_to_write_in_pmd) { + int pte_idx = 0; + const int batch_size = min_t(int, pages_to_write_in_pmd, 8); + + spin_lock(pte_lock); + for (; pte_idx < batch_size; ++pte_idx) { + int err = insert_page_in_batch_locked(mm, pmd, + addr, pages[curr_page_idx], prot); + if (unlikely(err)) { + spin_unlock(pte_lock); + ret = err; + remaining_pages_total -= pte_idx; + goto out; + } + addr += PAGE_SIZE; + ++curr_page_idx; + } + spin_unlock(pte_lock); + pages_to_write_in_pmd -= batch_size; + remaining_pages_total -= batch_size; + } + if (remaining_pages_total) + goto more; + ret = 0; +out: + *num = remaining_pages_total; + return ret; +} +#endif /* ifdef pte_index */ + +/** + * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock. + * @vma: user vma to map to + * @addr: target start user address of these pages + * @pages: source kernel pages + * @num: in: number of pages to map. out: number of pages that were *not* + * mapped. (0 means all pages were successfully mapped). + * + * Preferred over vm_insert_page() when inserting multiple pages. + * + * In case of error, we may have mapped a subset of the provided + * pages. It is the caller's responsibility to account for this case. + * + * The same restrictions apply as in vm_insert_page(). + */ +int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, + struct page **pages, unsigned long *num) +{ +#ifdef pte_index + const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1; + + if (addr < vma->vm_start || end_addr >= vma->vm_end) + return -EFAULT; + if (!(vma->vm_flags & VM_MIXEDMAP)) { + BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem)); + BUG_ON(vma->vm_flags & VM_PFNMAP); + vma->vm_flags |= VM_MIXEDMAP; + } + /* Defer page refcount checking till we're about to map that page. */ + return insert_pages(vma, addr, pages, num, vma->vm_page_prot); +#else + unsigned long idx = 0, pgcount = *num; + int err; + + for (; idx < pgcount; ++idx) { + err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]); + if (err) + break; + } + *num = pgcount - idx; + return err; +#endif /* ifdef pte_index */ +} +EXPORT_SYMBOL(vm_insert_pages); + /** * vm_insert_page - insert single page into user vma * @vma: user vma to map to