From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F7D6C4345F for ; Mon, 20 Jul 2020 09:25:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 24FC122B4E for ; Mon, 20 Jul 2020 09:25:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595237155; bh=9kPtPKwEUAnSuahV3W8pSHhDvS8uHdOx88OWN7WHnng=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Y9tIvjXTK762iL5bXhrLoVsqHy31har7s8FqpLfV5xzZWUIiy8J3SH8sa88QscBDP 0psxmTzKs7lJKr4ToqG0hFe+q3jbgu8Vp8L7tWjZqno66E7N0i1LvHcLYbMdy5Wk0m gcqKDSz25G8IPd6WiLDafvkvXSakWu80ekQDlYPI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728315AbgGTJZx (ORCPT ); Mon, 20 Jul 2020 05:25:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:39878 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727769AbgGTJZx (ORCPT ); Mon, 20 Jul 2020 05:25:53 -0400 Received: from aquarius.haifa.ibm.com (nesher1.haifa.il.ibm.com [195.110.40.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 890EF20684; Mon, 20 Jul 2020 09:25:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595237152; bh=9kPtPKwEUAnSuahV3W8pSHhDvS8uHdOx88OWN7WHnng=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=s1ZrP+vgWVhaXNgt090zvy4TPEalJa+qdnV/v1+MZkUKwcLPrQpdm6a/kUGs2V46p 2dDJWZzwv61H8u1Cd1OuHjNz7zAaqLs2fDKnaNBG9xohfo+hcCrz/zezMe3CVMy3lC plVjdUv3Danilnry2dO5745Ft+edWbwQaUoGzI5Y= From: Mike Rapoport To: linux-kernel@vger.kernel.org Cc: Alexander Viro , Andrew Morton , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , Elena Reshetova , "H. Peter Anvin" , Idan Yaniv , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Mike Rapoport , Mike Rapoport , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , 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-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org Subject: [PATCH 5/6] mm: secretmem: use PMD-size pages to amortize direct map fragmentation Date: Mon, 20 Jul 2020 12:24:34 +0300 Message-Id: <20200720092435.17469-6-rppt@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200720092435.17469-1-rppt@kernel.org> References: <20200720092435.17469-1-rppt@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 | 107 ++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 88 insertions(+), 19 deletions(-) diff --git a/mm/secretmem.c b/mm/secretmem.c index 2f65219baf80..dce56f84968f 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -25,24 +26,66 @@ #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) { - /* - * FIXME: use a cache of large pages to reduce the direct map - * fragmentation - */ - return alloc_page(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, PMD_PAGE_ORDER); + if (!page) + return -ENOMEM; + + addr = (unsigned long)page_address(page); + split_page(page, PMD_PAGE_ORDER); + + err = gen_pool_add(pool, addr, PMD_SIZE, NUMA_NO_NODE); + if (err) { + __free_pages(page, PMD_PAGE_ORDER); + return err; + } + + __kernel_map_pages(page, nr_pages, 0); + + return 0; +} + +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; @@ -51,7 +94,7 @@ 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); @@ -59,14 +102,8 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf) if (unlikely(ret)) goto err_put_page; - ret = set_direct_map_invalid_noflush(page); - 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; } @@ -74,8 +111,6 @@ 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); @@ -131,7 +166,11 @@ static int secretmem_migratepage(struct address_space *mapping, static void secretmem_freepage(struct page *page) { - set_direct_map_default_noflush(page); + 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 = { @@ -156,13 +195,18 @@ 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; @@ -176,6 +220,8 @@ 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: @@ -220,11 +266,34 @@ SYSCALL_DEFINE1(secretmemfd, 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); } -- 2.26.2