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: 11856089 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 59C9A14C0 for ; Mon, 26 Oct 2020 08:39:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 33CAB22400 for ; Mon, 26 Oct 2020 08:39:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603701565; bh=T40iRaLwQz12+uFzwB/HBDTs/ag1fyJ+pXo/CUd+ftI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=i2yy53aU53WxVDTLFyQOml/7ySqj0V43F3KgHvTlHxZs+FlFnotiGt4xJ+Qsj9hfr IXZ7Qx8czj1TG3eRrJtEFaLhGj5WqnCYc+9xlcXoHOqrsAFUXj8st9HKXeNkSTQC2f dtOuyu7/mB8963xDmJRj9rIGsJd1H0igUF1mLRmM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1771928AbgJZIjX (ORCPT ); Mon, 26 Oct 2020 04:39:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:49154 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1771911AbgJZIjK (ORCPT ); Mon, 26 Oct 2020 04:39:10 -0400 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 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org 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); }