From patchwork Mon Oct 26 08:37:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Rapoport X-Patchwork-Id: 11856081 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 4D063157C for ; Mon, 26 Oct 2020 08:39:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F06F922400 for ; Mon, 26 Oct 2020 08:39:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="i7+DYdgO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F06F922400 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1CEAD6B0071; Mon, 26 Oct 2020 04:39:12 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 17C656B0072; Mon, 26 Oct 2020 04:39:12 -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 043DE6B0073; Mon, 26 Oct 2020 04:39:11 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0238.hostedemail.com [216.40.44.238]) by kanga.kvack.org (Postfix) with ESMTP id CA46B6B0071 for ; Mon, 26 Oct 2020 04:39:11 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 6E9CA181AC9CB for ; Mon, 26 Oct 2020 08:39:11 +0000 (UTC) X-FDA: 77413426902.24.slave39_4312b1b27272 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id 38E541A4A5 for ; Mon, 26 Oct 2020 08:39:11 +0000 (UTC) X-Spam-Summary: 1,0,0,aa515c0d8cdab411,d41d8cd98f00b204,rppt@kernel.org,,RULES_HIT:2:41:355:379:541:800:960:966:973:988:989:1260:1311:1314:1345:1359:1437:1515:1535:1605:1730:1747:1777:1792:2196:2198:2199:2200:2393:2559:2562:2693:3138:3139:3140:3141:3142:3865:3866:3867:3868:3871:3872:3874:4049:4120:4385:5007:6119:6261:6653:6742:6743:7576:7875:7903:8603:8660:8957:9592:10004:11026:11473:11658:11914:12043:12291:12296:12297:12438:12517:12519:12555:12679:12683:12895:13141:13148:13161:13229:13230:13255:13894:14096:14394:21080:21324:21450:21451:21627:21939:21990:30054,0,RBL:198.145.29.99:@kernel.org:.lbl8.mailshell.net-62.2.0.100 64.100.201.201;04ygm1eo6jswbou56xubko1cwaecnocr4pa5n8rfntsrjuc878owjf51zsktzs7.x9ae8axjefptciapmy9frizfwq68qyi3ipjjsw4tm7nzz1isy3s9xruy4rgx5d3.o-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:25,LUA_SUMMARY:none X-HE-Tag: slave39_4312b1b27272 X-Filterd-Recvd-Size: 9219 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf07.hostedemail.com (Postfix) with ESMTP for ; Mon, 26 Oct 2020 08:39:10 +0000 (UTC) Received: from aquarius.haifa.ibm.com (nesher1.haifa.il.ibm.com [195.110.40.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B64FF223FD; Mon, 26 Oct 2020 08:39:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603701549; bh=T40iRaLwQz12+uFzwB/HBDTs/ag1fyJ+pXo/CUd+ftI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i7+DYdgOOAED08WdB438GSwMzbRCSH2loQlCtjivn8vq8W/9nnEK6bhy7qz1XvW3u NKqyOS+maJC6srqMf/a7rQA9IxD49vN2IB2I3M4qT/LKcoZ/uQm1FOja3q0bMtX4m9 A6rZ5frExyjgLh6+IZRHIEIcyvqBOG8xjZLL/nuY= From: Mike Rapoport To: Andrew Morton Cc: Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , David Hildenbrand , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Mark Rutland , Mike Rapoport , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org Subject: [PATCH v7 6/7] mm: secretmem: use PMD-size pages to amortize direct map fragmentation Date: Mon, 26 Oct 2020 10:37:51 +0200 Message-Id: <20201026083752.13267-7-rppt@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201026083752.13267-1-rppt@kernel.org> References: <20201026083752.13267-1-rppt@kernel.org> MIME-Version: 1.0 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: Mike Rapoport Removing a PAGE_SIZE page from the direct map every time such page is allocated for a secret memory mapping will cause severe fragmentation of the direct map. This fragmentation can be reduced by using PMD-size pages as a pool for small pages for secret memory mappings. Add a gen_pool per secretmem inode and lazily populate this pool with PMD-size pages. Signed-off-by: Mike Rapoport --- mm/secretmem.c | 124 ++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 107 insertions(+), 17 deletions(-) diff --git a/mm/secretmem.c b/mm/secretmem.c index 2a63db2ed132..4f9e07d212be 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -12,8 +12,10 @@ #include #include #include +#include #include #include +#include #include #include @@ -40,24 +42,80 @@ #define SECRETMEM_FLAGS_MASK SECRETMEM_MODE_MASK struct secretmem_ctx { + struct gen_pool *pool; unsigned int mode; }; -static struct page *secretmem_alloc_page(gfp_t gfp) +static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) { + unsigned long nr_pages = (1 << PMD_PAGE_ORDER); + struct gen_pool *pool = ctx->pool; + unsigned long addr; + struct page *page; + int err; + + page = alloc_pages(gfp | __GFP_ACCOUNT, PMD_PAGE_ORDER); + if (!page) + return -ENOMEM; + + addr = (unsigned long)page_address(page); + + err = set_direct_map_invalid_noflush(page, nr_pages); + if (err) + goto err_free_pages; + + err = gen_pool_add(pool, addr, PMD_SIZE, NUMA_NO_NODE); + if (err) + goto err_set_direct_map; + + split_page(page, PMD_PAGE_ORDER); + flush_tlb_kernel_range(addr, addr + PMD_SIZE); + + return 0; + +err_set_direct_map: /* - * FIXME: use a cache of large pages to reduce the direct map - * fragmentation + * If a split of PUD-size page was required, it already happened + * when we made the pages invalid which guarantees that this call + * won't fail */ - return alloc_page(gfp); + set_direct_map_default_noflush(page, nr_pages); + +err_free_pages: + __free_pages(page, PMD_PAGE_ORDER); + return err; +} + +static struct page *secretmem_alloc_page(struct secretmem_ctx *ctx, + gfp_t gfp) +{ + struct gen_pool *pool = ctx->pool; + unsigned long addr; + struct page *page; + int err; + + if (gen_pool_avail(pool) < PAGE_SIZE) { + err = secretmem_pool_increase(ctx, gfp); + if (err) + return NULL; + } + + addr = gen_pool_alloc(pool, PAGE_SIZE); + if (!addr) + return NULL; + + page = virt_to_page(addr); + get_page(page); + + return page; } static vm_fault_t secretmem_fault(struct vm_fault *vmf) { + struct secretmem_ctx *ctx = vmf->vma->vm_file->private_data; struct address_space *mapping = vmf->vma->vm_file->f_mapping; struct inode *inode = file_inode(vmf->vma->vm_file); pgoff_t offset = vmf->pgoff; - unsigned long addr; struct page *page; int ret = 0; @@ -66,22 +124,22 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf) page = find_get_entry(mapping, offset); if (!page) { - page = secretmem_alloc_page(vmf->gfp_mask); + page = secretmem_alloc_page(ctx, vmf->gfp_mask); if (!page) return vmf_error(-ENOMEM); + /* + * add_to_page_cache() calls mem_cgroup_charge(), so we + * need to uncharge here to avoid double accounting + */ + memcg_kmem_uncharge_page(page, 0); + ret = add_to_page_cache(page, mapping, offset, vmf->gfp_mask); if (unlikely(ret)) goto err_put_page; - ret = set_direct_map_invalid_noflush(page, 1); - if (ret) - goto err_del_page_cache; - - addr = (unsigned long)page_address(page); - flush_tlb_kernel_range(addr, addr + PAGE_SIZE); - __SetPageUptodate(page); + set_page_private(page, (unsigned long)ctx); ret = VM_FAULT_LOCKED; } @@ -89,8 +147,6 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf) vmf->page = page; return ret; -err_del_page_cache: - delete_from_page_cache(page); err_put_page: put_page(page); return vmf_error(ret); @@ -143,7 +199,11 @@ static int secretmem_migratepage(struct address_space *mapping, static void secretmem_freepage(struct page *page) { - set_direct_map_default_noflush(page, 1); + unsigned long addr = (unsigned long)page_address(page); + struct secretmem_ctx *ctx = (struct secretmem_ctx *)page_private(page); + struct gen_pool *pool = ctx->pool; + + gen_pool_free(pool, addr, PAGE_SIZE); } static const struct address_space_operations secretmem_aops = { @@ -178,13 +238,18 @@ static struct file *secretmem_file_create(unsigned long flags) if (!ctx) goto err_free_inode; + ctx->pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE); + if (!ctx->pool) + goto err_free_ctx; + file = alloc_file_pseudo(inode, secretmem_mnt, "secretmem", O_RDWR, &secretmem_fops); if (IS_ERR(file)) - goto err_free_ctx; + goto err_free_pool; mapping_set_unevictable(inode->i_mapping); + inode->i_private = ctx; inode->i_mapping->private_data = ctx; inode->i_mapping->a_ops = &secretmem_aops; @@ -198,6 +263,8 @@ static struct file *secretmem_file_create(unsigned long flags) return file; +err_free_pool: + gen_pool_destroy(ctx->pool); err_free_ctx: kfree(ctx); err_free_inode: @@ -236,11 +303,34 @@ SYSCALL_DEFINE1(memfd_secret, unsigned long, flags) return err; } +static void secretmem_cleanup_chunk(struct gen_pool *pool, + struct gen_pool_chunk *chunk, void *data) +{ + unsigned long start = chunk->start_addr; + unsigned long end = chunk->end_addr; + unsigned long nr_pages, addr; + + nr_pages = (end - start + 1) / PAGE_SIZE; + __kernel_map_pages(virt_to_page(start), nr_pages, 1); + + for (addr = start; addr < end; addr += PAGE_SIZE) + put_page(virt_to_page(addr)); +} + +static void secretmem_cleanup_pool(struct secretmem_ctx *ctx) +{ + struct gen_pool *pool = ctx->pool; + + gen_pool_for_each_chunk(pool, secretmem_cleanup_chunk, ctx); + gen_pool_destroy(pool); +} + static void secretmem_evict_inode(struct inode *inode) { struct secretmem_ctx *ctx = inode->i_private; truncate_inode_pages_final(&inode->i_data); + secretmem_cleanup_pool(ctx); clear_inode(inode); kfree(ctx); }