From patchwork Tue Aug 22 01:54:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Joel Fernandes \(Google\)" X-Patchwork-Id: 716335 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08740EE49AB for ; Tue, 22 Aug 2023 01:55:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232164AbjHVBzY (ORCPT ); Mon, 21 Aug 2023 21:55:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58918 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231974AbjHVBzX (ORCPT ); Mon, 21 Aug 2023 21:55:23 -0400 Received: from mail-il1-x132.google.com (mail-il1-x132.google.com [IPv6:2607:f8b0:4864:20::132]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B155D180 for ; Mon, 21 Aug 2023 18:55:21 -0700 (PDT) Received: by mail-il1-x132.google.com with SMTP id e9e14a558f8ab-34ca2fcdf9fso6954145ab.0 for ; Mon, 21 Aug 2023 18:55:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1692669321; x=1693274121; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=CsH3vkDr9agJVI3SouFCcK5RkzBRN3iHA9ib5+au0Rw=; b=CzldOLSR/1CFch60cKxnxJV7KC0TbczE/AS7NU3vcELLGEqTO96428h5zAJIQx9q47 qJfdzOYkvoVEnJLl8uynvnnrnlYgm5gqjmtv+3cgEgtH/Nt4FRLdULpgo/k3RjIb+SnU WTKw5yuYuGQnOEhCHelds3JU0dgsb9m7n0OS8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692669321; x=1693274121; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=CsH3vkDr9agJVI3SouFCcK5RkzBRN3iHA9ib5+au0Rw=; b=EwgqDAhHyO6uPPSJtpyMpImdCRVd+fuVBn4/w7Iaw/8w+ZbRHV1v+I1z0iP1Mdds5m 6dLb2JLyjsdK4+bCJ9jLyVdwQ1fg4zlnj/Pw957Z2SycCJG4Oth70Lm+J5k8BU67/duH z0rjZm1kr8Ddq8CCfPNZ3soocTjX6M8+DaqBUO4CReAEC9m8QHqUqhCEERAGpPrGiP6f KzVK50UMCZ0pzl1552fsPBgVUI2GfEE7+TaFwL8YJqzKhVBS56vpL+MfSEkfVVq9yJGA 6KoMdy83N3GAgfQeBHeph3puCZZZKaG6TCOJeIH1iGBdBD8h5OSWvNJin4oONgKiO0xV 3hMg== X-Gm-Message-State: AOJu0Yy0KTQVWgbAufEa9q64hn2790deYJeErk4wNfvEDPgFBjjFwnij 6LbnpJIcMW5FnPxtFDI7tnPm8A== X-Google-Smtp-Source: AGHT+IFjdGA7XRGfiXyy54FM+yhexl4gbxKokE/+1QN35KTpxnmuosD5M/koT6P5pAtsasmz/S2vng== X-Received: by 2002:a05:6e02:dce:b0:349:9938:a9b3 with SMTP id l14-20020a056e020dce00b003499938a9b3mr9158834ilj.3.1692669321018; Mon, 21 Aug 2023 18:55:21 -0700 (PDT) Received: from joelboxx5.c.googlers.com.com (156.190.123.34.bc.googleusercontent.com. [34.123.190.156]) by smtp.gmail.com with ESMTPSA id q11-20020a92d40b000000b0034886587bdcsm2907390ilm.18.2023.08.21.18.55.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Aug 2023 18:55:20 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , Linus Torvalds , linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Shuah Khan , Vlastimil Babka , Michal Hocko , Lorenzo Stoakes , Kirill A Shutemov , "Liam R. Howlett" , "Paul E. McKenney" , Suren Baghdasaryan , Kalesh Singh , Lokesh Gidra Subject: [PATCH v5 1/7] mm/mremap: Optimize the start addresses in move_page_tables() Date: Tue, 22 Aug 2023 01:54:54 +0000 Message-ID: <20230822015501.791637-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.rc1.204.g551eb34607-goog In-Reply-To: <20230822015501.791637-1-joel@joelfernandes.org> References: <20230822015501.791637-1-joel@joelfernandes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Recently, we see reports [1] of a warning that triggers due to move_page_tables() doing a downward and overlapping move on a mutually-aligned offset within a PMD. By mutual alignment, I mean the source and destination addresses of the mremap are at the same offset within a PMD. This mutual alignment along with the fact that the move is downward is sufficient to cause a warning related to having an allocated PMD that does not have PTEs in it. This warning will only trigger when there is mutual alignment in the move operation. A solution, as suggested by Linus Torvalds [2], is to initiate the copy process at the PMD level whenever such alignment is present. Implementing this approach will not only prevent the warning from being triggered, but it will also optimize the operation as this method should enhance the speed of the copy process whenever there's a possibility to start copying at the PMD level. Some more points: a. The optimization can be done only when both the source and destination of the mremap do not have anything mapped below it up to a PMD boundary. I add support to detect that. b. #1 is not a problem for the call to move_page_tables() from exec.c as nothing is expected to be mapped below the source. However, for non-overlapping mutually aligned moves as triggered by mremap(2), I added support for checking such cases. c. I currently only optimize for PMD moves, in the future I/we can build on this work and do PUD moves as well if there is a need for this. But I want to take it one step at a time. d. We need to be careful about mremap of ranges within the VMA itself. For this purpose, I added checks to determine if the address after alignment falls within its VMA itself. [1] https://lore.kernel.org/all/ZB2GTBD%2FLWTrkOiO@dhcp22.suse.cz/ [2] https://lore.kernel.org/all/CAHk-=whd7msp8reJPfeGNyt0LiySMT0egExx3TVZSX3Ok6X=9g@mail.gmail.com/ Suggested-by: Linus Torvalds Signed-off-by: Joel Fernandes (Google) --- mm/mremap.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) diff --git a/mm/mremap.c b/mm/mremap.c index 11e06e4ab33b..035fbf542a8f 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -489,6 +489,53 @@ static bool move_pgt_entry(enum pgt_entry entry, struct vm_area_struct *vma, return moved; } +/* + * A helper to check if a previous mapping exists. Required for + * move_page_tables() and realign_addr() to determine if a previous mapping + * exists before we can do realignment optimizations. + */ +static bool can_align_down(struct vm_area_struct *vma, unsigned long addr_to_align, + unsigned long mask) +{ + unsigned long addr_masked = addr_to_align & mask; + + /* + * If @addr_to_align of either source or destination is not the beginning + * of the corresponding VMA, we can't align down or we will destroy part + * of the current mapping. + */ + if (vma->vm_start != addr_to_align) + return false; + + /* + * Make sure the realignment doesn't cause the address to fall on an + * existing mapping. + */ + return find_vma_intersection(vma->vm_mm, addr_masked, addr_to_align) == NULL; +} + +/* Opportunistically realign to specified boundary for faster copy. */ +static void try_realign_addr(unsigned long *old_addr, struct vm_area_struct *old_vma, + unsigned long *new_addr, struct vm_area_struct *new_vma, + unsigned long mask) +{ + /* Skip if the addresses are already aligned. */ + if ((*old_addr & ~mask) == 0) + return; + + /* Only realign if the new and old addresses are mutually aligned. */ + if ((*old_addr & ~mask) != (*new_addr & ~mask)) + return; + + /* Ensure realignment doesn't cause overlap with existing mappings. */ + if (!can_align_down(old_vma, *old_addr, mask) || + !can_align_down(new_vma, *new_addr, mask)) + return; + + *old_addr = *old_addr & mask; + *new_addr = *new_addr & mask; +} + unsigned long move_page_tables(struct vm_area_struct *vma, unsigned long old_addr, struct vm_area_struct *new_vma, unsigned long new_addr, unsigned long len, @@ -508,6 +555,14 @@ unsigned long move_page_tables(struct vm_area_struct *vma, return move_hugetlb_page_tables(vma, new_vma, old_addr, new_addr, len); + /* + * If possible, realign addresses to PMD boundary for faster copy. + * Only realign if the mremap copying hits a PMD boundary. + */ + if ((vma != new_vma) + && (len >= PMD_SIZE - (old_addr & ~PMD_MASK))) + try_realign_addr(&old_addr, vma, &new_addr, new_vma, PMD_MASK); + flush_cache_range(vma, old_addr, old_end); mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma->vm_mm, old_addr, old_end); @@ -577,6 +632,13 @@ unsigned long move_page_tables(struct vm_area_struct *vma, mmu_notifier_invalidate_range_end(&range); + /* + * Prevent negative return values when {old,new}_addr was realigned + * but we broke out of the above loop for the first PMD itself. + */ + if (len + old_addr < old_end) + return 0; + return len + old_addr - old_end; /* how much done */ } From patchwork Tue Aug 22 01:54:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Joel Fernandes \(Google\)" X-Patchwork-Id: 716334 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 651D9EE4996 for ; Tue, 22 Aug 2023 01:55:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232176AbjHVBz0 (ORCPT ); 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[34.123.190.156]) by smtp.gmail.com with ESMTPSA id q11-20020a92d40b000000b0034886587bdcsm2907390ilm.18.2023.08.21.18.55.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Aug 2023 18:55:22 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Shuah Khan , Vlastimil Babka , Michal Hocko , Linus Torvalds , Lorenzo Stoakes , Kirill A Shutemov , "Liam R. Howlett" , "Paul E. McKenney" , Suren Baghdasaryan , Kalesh Singh , Lokesh Gidra Subject: [PATCH v5 3/7] selftests: mm: Fix failure case when new remap region was not found Date: Tue, 22 Aug 2023 01:54:56 +0000 Message-ID: <20230822015501.791637-4-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.rc1.204.g551eb34607-goog In-Reply-To: <20230822015501.791637-1-joel@joelfernandes.org> References: <20230822015501.791637-1-joel@joelfernandes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org When a valid remap region could not be found, the source mapping is not cleaned up. Fix the goto statement such that the clean up happens. Signed-off-by: Joel Fernandes (Google) Reviewed-by: Lorenzo Stoakes --- tools/testing/selftests/mm/mremap_test.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/mm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c index 5c3773de9f0f..6822d657f589 100644 --- a/tools/testing/selftests/mm/mremap_test.c +++ b/tools/testing/selftests/mm/mremap_test.c @@ -316,7 +316,7 @@ static long long remap_region(struct config c, unsigned int threshold_mb, if (addr + c.dest_alignment < addr) { ksft_print_msg("Couldn't find a valid region to remap to\n"); ret = -1; - goto out; + goto clean_up_src; } addr += c.dest_alignment; } From patchwork Tue Aug 22 01:54:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Joel Fernandes \(Google\)" X-Patchwork-Id: 716333 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 56BB0EE4996 for ; Tue, 22 Aug 2023 01:55:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232207AbjHVBzs (ORCPT ); Mon, 21 Aug 2023 21:55:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53864 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232193AbjHVBzq (ORCPT ); Mon, 21 Aug 2023 21:55:46 -0400 Received: from mail-il1-x134.google.com (mail-il1-x134.google.com [IPv6:2607:f8b0:4864:20::134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5553189 for ; Mon, 21 Aug 2023 18:55:25 -0700 (PDT) Received: by mail-il1-x134.google.com with SMTP id e9e14a558f8ab-34cacab5e33so5168275ab.2 for ; Mon, 21 Aug 2023 18:55:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1692669325; x=1693274125; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Axho/C2d3GxLBo+LZnFUqjVo2BRyImetugTXkfwiHhM=; b=dcsD/55UXOmDc6JKsWv76PEhXAR+DHegc6mDX9k2Jt5pnmj+7kdpAShITM6SWA8XVM +P0Xr5RhvhwbMxDE/FrWsVMmWu1bcOxe96a9Sj6svTHwHS6oAJLaYFyQ1ynl3xKLRc8F pQ+Bm6+1vG8lQOIPDNwuUzZJIUNfw4RUA4nHM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692669325; x=1693274125; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Axho/C2d3GxLBo+LZnFUqjVo2BRyImetugTXkfwiHhM=; b=B9g3DkALZYAfXkMtFV1nWwfPSSpmWe9/Rv96g8PGPDk7ownI7igrG40CsyaUBxHRQg Ow/mOjJ9XauO7ut9qJCvTXkuuQ/jKFV4hS1xKThpCTv7U2lyKL8eLmA1ygIebyvBm4BY YNM1wVuADoHKfhi6C+a2E79v3yxML7zcRej9MWAwDWEHxkTaU+YsUB9j+BFXRMEwxRud /TTe38Omqt53xHdCaFV+dEKjYqdt2QPEztbSX42HpDuTiS0/I1lMfmRu02E7P8kO2rDc fWzzr2irJsJINiqQVBSIk+/ffhf0+6L37h6dgyDB1riBbts5LjS7xsO1H0U/Rq8jXiyR KWUQ== X-Gm-Message-State: AOJu0YxB3jjl6e99WdOeoR8sPK0+/8JQyl8rBVrjpt7pd2IqMHw55tF0 ECEdQQYE+dtkQVhuknOAMpHvFw== X-Google-Smtp-Source: AGHT+IGZXIerY8NUWYReuIPpDpvFlLHcIDml9i8pszriAMC0UzQ9sup1GqyFJEY4NY5BpU4X49RLVw== X-Received: by 2002:a05:6e02:dce:b0:349:a4f8:8815 with SMTP id l14-20020a056e020dce00b00349a4f88815mr9945123ilj.2.1692669325296; Mon, 21 Aug 2023 18:55:25 -0700 (PDT) Received: from joelboxx5.c.googlers.com.com (156.190.123.34.bc.googleusercontent.com. [34.123.190.156]) by smtp.gmail.com with ESMTPSA id q11-20020a92d40b000000b0034886587bdcsm2907390ilm.18.2023.08.21.18.55.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Aug 2023 18:55:24 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Shuah Khan , Vlastimil Babka , Michal Hocko , Linus Torvalds , Lorenzo Stoakes , Kirill A Shutemov , "Liam R. Howlett" , "Paul E. McKenney" , Suren Baghdasaryan , Kalesh Singh , Lokesh Gidra Subject: [PATCH v5 5/7] selftests: mm: Add a test for remapping to area immediately after existing mapping Date: Tue, 22 Aug 2023 01:54:58 +0000 Message-ID: <20230822015501.791637-6-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.rc1.204.g551eb34607-goog In-Reply-To: <20230822015501.791637-1-joel@joelfernandes.org> References: <20230822015501.791637-1-joel@joelfernandes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org This patch adds support for verifying that we correctly handle the situation where something is already mapped before the destination of the remap. Any realignment of destination address and PMD-copy will destroy that existing mapping. In such cases, we need to avoid doing the optimization. To test this, we map an area called the preamble before the remap region. Then we verify after the mremap operation that this region did not get corrupted. Putting some prints in the kernel, I verified that we optimize correctly in different situations: Optimize when there is alignment and no previous mapping (this is tested by previous patch). can_align_down(old_vma->vm_start=2900000, old_addr=2900000, mask=-2097152): 0 can_align_down(new_vma->vm_start=2f00000, new_addr=2f00000, mask=-2097152): 0 === Starting move_page_tables === Doing PUD move for 2800000 -> 2e00000 of extent=200000 <-- Optimization Doing PUD move for 2a00000 -> 3000000 of extent=200000 Doing PUD move for 2c00000 -> 3200000 of extent=200000 Don't optimize when there is alignment but there is previous mapping (this is tested by this patch). Notice that can_align_down() returns 1 for the destination mapping as we detected there is something there. can_align_down(old_vma->vm_start=2900000, old_addr=2900000, mask=-2097152): 0 can_align_down(new_vma->vm_start=5700000, new_addr=5700000, mask=-2097152): 1 === Starting move_page_tables === Doing move_ptes for 2900000 -> 5700000 of extent=100000 <-- Unoptimized Doing PUD move for 2a00000 -> 5800000 of extent=200000 Doing PUD move for 2c00000 -> 5a00000 of extent=200000 Signed-off-by: Joel Fernandes (Google) Reviewed-by: Lorenzo Stoakes --- tools/testing/selftests/mm/mremap_test.c | 57 +++++++++++++++++++++--- 1 file changed, 52 insertions(+), 5 deletions(-) diff --git a/tools/testing/selftests/mm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c index 6304eb0947a3..d7366074e2a8 100644 --- a/tools/testing/selftests/mm/mremap_test.c +++ b/tools/testing/selftests/mm/mremap_test.c @@ -29,6 +29,7 @@ struct config { unsigned long long dest_alignment; unsigned long long region_size; int overlapping; + int dest_preamble_size; }; struct test { @@ -283,7 +284,7 @@ static void *get_source_mapping(struct config c) static long long remap_region(struct config c, unsigned int threshold_mb, char pattern_seed) { - void *addr, *src_addr, *dest_addr; + void *addr, *src_addr, *dest_addr, *dest_preamble_addr; unsigned long long i; struct timespec t_start = {0, 0}, t_end = {0, 0}; long long start_ns, end_ns, align_mask, ret, offset; @@ -300,7 +301,7 @@ static long long remap_region(struct config c, unsigned int threshold_mb, goto out; } - /* Set byte pattern */ + /* Set byte pattern for source block. */ srand(pattern_seed); for (i = 0; i < threshold; i++) memset((char *) src_addr + i, (char) rand(), 1); @@ -312,6 +313,9 @@ static long long remap_region(struct config c, unsigned int threshold_mb, addr = (void *) (((unsigned long long) src_addr + c.region_size + offset) & align_mask); + /* Remap after the destination block preamble. */ + addr += c.dest_preamble_size; + /* See comment in get_source_mapping() */ if (!((unsigned long long) addr & c.dest_alignment)) addr = (void *) ((unsigned long long) addr | c.dest_alignment); @@ -327,6 +331,24 @@ static long long remap_region(struct config c, unsigned int threshold_mb, addr += c.dest_alignment; } + if (c.dest_preamble_size) { + dest_preamble_addr = mmap((void *) addr - c.dest_preamble_size, c.dest_preamble_size, + PROT_READ | PROT_WRITE, + MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED, + -1, 0); + if (dest_preamble_addr == MAP_FAILED) { + ksft_print_msg("Failed to map dest preamble region: %s\n", + strerror(errno)); + ret = -1; + goto clean_up_src; + } + + /* Set byte pattern for the dest preamble block. */ + srand(pattern_seed); + for (i = 0; i < c.dest_preamble_size; i++) + memset((char *) dest_preamble_addr + i, (char) rand(), 1); + } + clock_gettime(CLOCK_MONOTONIC, &t_start); dest_addr = mremap(src_addr, c.region_size, c.region_size, MREMAP_MAYMOVE|MREMAP_FIXED, (char *) addr); @@ -335,7 +357,7 @@ static long long remap_region(struct config c, unsigned int threshold_mb, if (dest_addr == MAP_FAILED) { ksft_print_msg("mremap failed: %s\n", strerror(errno)); ret = -1; - goto clean_up_src; + goto clean_up_dest_preamble; } /* Verify byte pattern after remapping */ @@ -353,6 +375,23 @@ static long long remap_region(struct config c, unsigned int threshold_mb, } } + /* Verify the dest preamble byte pattern after remapping */ + if (c.dest_preamble_size) { + srand(pattern_seed); + for (i = 0; i < c.dest_preamble_size; i++) { + char c = (char) rand(); + + if (((char *) dest_preamble_addr)[i] != c) { + ksft_print_msg("Preamble data after remap doesn't match at offset %d\n", + i); + ksft_print_msg("Expected: %#x\t Got: %#x\n", c & 0xff, + ((char *) dest_preamble_addr)[i] & 0xff); + ret = -1; + goto clean_up_dest; + } + } + } + start_ns = t_start.tv_sec * NS_PER_SEC + t_start.tv_nsec; end_ns = t_end.tv_sec * NS_PER_SEC + t_end.tv_nsec; ret = end_ns - start_ns; @@ -365,6 +404,9 @@ static long long remap_region(struct config c, unsigned int threshold_mb, */ clean_up_dest: munmap(dest_addr, c.region_size); +clean_up_dest_preamble: + if (c.dest_preamble_size && dest_preamble_addr) + munmap(dest_preamble_addr, c.dest_preamble_size); clean_up_src: munmap(src_addr, c.region_size); out: @@ -440,7 +482,7 @@ static int parse_args(int argc, char **argv, unsigned int *threshold_mb, return 0; } -#define MAX_TEST 14 +#define MAX_TEST 15 #define MAX_PERF_TEST 3 int main(int argc, char **argv) { @@ -449,7 +491,7 @@ int main(int argc, char **argv) unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD; unsigned int pattern_seed; int num_expand_tests = 2; - struct test test_cases[MAX_TEST]; + struct test test_cases[MAX_TEST] = {}; struct test perf_test_cases[MAX_PERF_TEST]; int page_size; time_t t; @@ -510,6 +552,11 @@ int main(int argc, char **argv) test_cases[13] = MAKE_TEST(_1MB, _1MB, _5MB, NON_OVERLAPPING, EXPECT_SUCCESS, "5MB mremap - Source 1MB-aligned, Destination 1MB-aligned"); + /* Src and Dest addr 1MB aligned. 5MB mremap. */ + test_cases[14] = MAKE_TEST(_1MB, _1MB, _5MB, NON_OVERLAPPING, EXPECT_SUCCESS, + "5MB mremap - Source 1MB-aligned, Dest 1MB-aligned with 40MB Preamble"); + test_cases[14].config.dest_preamble_size = 10 * _4MB; + perf_test_cases[0] = MAKE_TEST(page_size, page_size, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS, "1GB mremap - Source PTE-aligned, Destination PTE-aligned"); /* From patchwork Tue Aug 22 01:55:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Joel Fernandes \(Google\)" X-Patchwork-Id: 716332 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BAE24EE49A6 for ; Tue, 22 Aug 2023 01:56:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231459AbjHVB4n (ORCPT ); Mon, 21 Aug 2023 21:56:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232172AbjHVBzs (ORCPT ); Mon, 21 Aug 2023 21:55:48 -0400 Received: from mail-il1-x135.google.com (mail-il1-x135.google.com [IPv6:2607:f8b0:4864:20::135]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2356F1A1 for ; 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[34.123.190.156]) by smtp.gmail.com with ESMTPSA id q11-20020a92d40b000000b0034886587bdcsm2907390ilm.18.2023.08.21.18.55.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Aug 2023 18:55:26 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: Joel Fernandes , linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Shuah Khan , Vlastimil Babka , Michal Hocko , Linus Torvalds , Lorenzo Stoakes , Kirill A Shutemov , "Liam R. Howlett" , "Paul E. McKenney" , Suren Baghdasaryan , Kalesh Singh , Lokesh Gidra Subject: [PATCH v5 7/7] selftests: mm: Add a test for moving from an offset from start of mapping Date: Tue, 22 Aug 2023 01:55:00 +0000 Message-ID: <20230822015501.791637-8-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.rc1.204.g551eb34607-goog In-Reply-To: <20230822015501.791637-1-joel@joelfernandes.org> References: <20230822015501.791637-1-joel@joelfernandes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org From: Joel Fernandes It is possible that the aligned address falls on no existing mapping, however that does not mean that we can just align it down to that. This test verifies that the "vma->vm_start != addr_to_align" check in can_align_down() prevents disastrous results if aligning down when source and dest are mutually aligned within a PMD but the source/dest addresses requested are not at the beginning of the respective mapping containing these addresses. Signed-off-by: Joel Fernandes (Google) Reviewed-by: Lorenzo Stoakes --- tools/testing/selftests/mm/mremap_test.c | 189 ++++++++++++++++------- 1 file changed, 134 insertions(+), 55 deletions(-) diff --git a/tools/testing/selftests/mm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c index f45d1abedc9c..c71ac8306c89 100644 --- a/tools/testing/selftests/mm/mremap_test.c +++ b/tools/testing/selftests/mm/mremap_test.c @@ -24,6 +24,7 @@ #define MIN(X, Y) ((X) < (Y) ? (X) : (Y)) #define SIZE_MB(m) ((size_t)m * (1024 * 1024)) +#define SIZE_KB(k) ((size_t)k * 1024) struct config { unsigned long long src_alignment; @@ -148,6 +149,60 @@ static bool is_range_mapped(FILE *maps_fp, void *start, void *end) return success; } +/* + * Returns the start address of the mapping on success, else returns + * NULL on failure. + */ +static void *get_source_mapping(struct config c) +{ + unsigned long long addr = 0ULL; + void *src_addr = NULL; + unsigned long long mmap_min_addr; + + mmap_min_addr = get_mmap_min_addr(); + /* + * For some tests, we need to not have any mappings below the + * source mapping. Add some headroom to mmap_min_addr for this. + */ + mmap_min_addr += 10 * _4MB; + +retry: + addr += c.src_alignment; + if (addr < mmap_min_addr) + goto retry; + + src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE, + MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED, + -1, 0); + if (src_addr == MAP_FAILED) { + if (errno == EPERM || errno == EEXIST) + goto retry; + goto error; + } + /* + * Check that the address is aligned to the specified alignment. + * Addresses which have alignments that are multiples of that + * specified are not considered valid. For instance, 1GB address is + * 2MB-aligned, however it will not be considered valid for a + * requested alignment of 2MB. This is done to reduce coincidental + * alignment in the tests. + */ + if (((unsigned long long) src_addr & (c.src_alignment - 1)) || + !((unsigned long long) src_addr & c.src_alignment)) { + munmap(src_addr, c.region_size); + goto retry; + } + + if (!src_addr) + goto error; + + return src_addr; +error: + ksft_print_msg("Failed to map source region: %s\n", + strerror(errno)); + return NULL; +} + /* * This test validates that merge is called when expanding a mapping. * Mapping containing three pages is created, middle page is unmapped @@ -300,60 +355,6 @@ static void mremap_move_within_range(char pattern_seed) ksft_test_result_fail("%s\n", test_name); } -/* - * Returns the start address of the mapping on success, else returns - * NULL on failure. - */ -static void *get_source_mapping(struct config c) -{ - unsigned long long addr = 0ULL; - void *src_addr = NULL; - unsigned long long mmap_min_addr; - - mmap_min_addr = get_mmap_min_addr(); - /* - * For some tests, we need to not have any mappings below the - * source mapping. Add some headroom to mmap_min_addr for this. - */ - mmap_min_addr += 10 * _4MB; - -retry: - addr += c.src_alignment; - if (addr < mmap_min_addr) - goto retry; - - src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE, - MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED, - -1, 0); - if (src_addr == MAP_FAILED) { - if (errno == EPERM || errno == EEXIST) - goto retry; - goto error; - } - /* - * Check that the address is aligned to the specified alignment. - * Addresses which have alignments that are multiples of that - * specified are not considered valid. For instance, 1GB address is - * 2MB-aligned, however it will not be considered valid for a - * requested alignment of 2MB. This is done to reduce coincidental - * alignment in the tests. - */ - if (((unsigned long long) src_addr & (c.src_alignment - 1)) || - !((unsigned long long) src_addr & c.src_alignment)) { - munmap(src_addr, c.region_size); - goto retry; - } - - if (!src_addr) - goto error; - - return src_addr; -error: - ksft_print_msg("Failed to map source region: %s\n", - strerror(errno)); - return NULL; -} - /* Returns the time taken for the remap on success else returns -1. */ static long long remap_region(struct config c, unsigned int threshold_mb, char pattern_seed) @@ -487,6 +488,83 @@ static long long remap_region(struct config c, unsigned int threshold_mb, return ret; } +/* + * Verify that an mremap aligning down does not destroy + * the beginning of the mapping just because the aligned + * down address landed on a mapping that maybe does not exist. + */ +static void mremap_move_1mb_from_start(char pattern_seed) +{ + char *test_name = "mremap move 1mb from start at 2MB+256KB aligned src"; + void *src = NULL, *dest = NULL; + int i, success = 1; + + /* Config to reuse get_source_mapping() to do an aligned mmap. */ + struct config c = { + .src_alignment = SIZE_MB(1) + SIZE_KB(256), + .region_size = SIZE_MB(6) + }; + + src = get_source_mapping(c); + if (!src) { + success = 0; + goto out; + } + + c.src_alignment = SIZE_MB(1) + SIZE_KB(256); + dest = get_source_mapping(c); + if (!dest) { + success = 0; + goto out; + } + + /* Set byte pattern for source block. */ + srand(pattern_seed); + for (i = 0; i < SIZE_MB(2); i++) { + ((char *)src)[i] = (char) rand(); + } + + /* + * Unmap the beginning of dest so that the aligned address + * falls on no mapping. + */ + munmap(dest, SIZE_MB(1)); + + void *new_ptr = mremap(src + SIZE_MB(1), SIZE_MB(1), SIZE_MB(1), + MREMAP_MAYMOVE | MREMAP_FIXED, dest + SIZE_MB(1)); + if (new_ptr == MAP_FAILED) { + perror("mremap"); + success = 0; + goto out; + } + + /* Verify byte pattern after remapping */ + srand(pattern_seed); + for (i = 0; i < SIZE_MB(1); i++) { + char c = (char) rand(); + + if (((char *)src)[i] != c) { + ksft_print_msg("Data at src at %d got corrupted due to unrelated mremap\n", + i); + ksft_print_msg("Expected: %#x\t Got: %#x\n", c & 0xff, + ((char *) src)[i] & 0xff); + success = 0; + } + } + +out: + if (src && munmap(src, c.region_size) == -1) + perror("munmap src"); + + if (dest && munmap(dest, c.region_size) == -1) + perror("munmap dest"); + + if (success) + ksft_test_result_pass("%s\n", test_name); + else + ksft_test_result_fail("%s\n", test_name); +} + static void run_mremap_test_case(struct test test_case, int *failures, unsigned int threshold_mb, unsigned int pattern_seed) @@ -565,7 +643,7 @@ int main(int argc, char **argv) unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD; unsigned int pattern_seed; int num_expand_tests = 2; - int num_misc_tests = 1; + int num_misc_tests = 2; struct test test_cases[MAX_TEST] = {}; struct test perf_test_cases[MAX_PERF_TEST]; int page_size; @@ -666,6 +744,7 @@ int main(int argc, char **argv) fclose(maps_fp); mremap_move_within_range(pattern_seed); + mremap_move_1mb_from_start(pattern_seed); if (run_perf_tests) { ksft_print_msg("\n%s\n",