From patchwork Wed May 24 15:32:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 685534 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 CD21BC77B7A for ; Wed, 24 May 2023 15:33:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235949AbjEXPc7 (ORCPT ); Wed, 24 May 2023 11:32:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235916AbjEXPc5 (ORCPT ); Wed, 24 May 2023 11:32:57 -0400 Received: from mail-qk1-x735.google.com (mail-qk1-x735.google.com [IPv6:2607:f8b0:4864:20::735]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EB1B18E for ; Wed, 24 May 2023 08:32:54 -0700 (PDT) Received: by mail-qk1-x735.google.com with SMTP id af79cd13be357-75b0f2ce4b7so84868885a.2 for ; Wed, 24 May 2023 08:32:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1684942373; x=1687534373; 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=KHeROvIq4CSC2FMFzmeiM0i6iG6dvZWzuyFWS5s0CDs=; b=wlQ8v0bsuOA9hOIgsHnV0xzgFyBlbO7E6j9Va6zOMO1Lq54V7yVfco94su2p9uA3zT GAryTJuE/eyHkMObMXy25pmdmQHP7wJqp+4j8yOi3nIDdmPVuWoRz9/X7tM7FdDjEOMh Zp+su0joqmuWavruN1PE8gqEZA6j486QyZYcg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684942373; x=1687534373; 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=KHeROvIq4CSC2FMFzmeiM0i6iG6dvZWzuyFWS5s0CDs=; b=G8Zes0U/p/uylOtv1nmsutHz+/16C29k7KvqhuMICI3Ex9K5y781X5Ji3LpOjrTJDn dtRpIsjw5k4nLaumSc143OFp2NEDFHqKGO+mj4c9N9krJEUNgPTu81Ds6ijynj2WEgz3 SihI+CJRAcG/rr3/61m2HsEhqektGQLeZgO3wsrXkU/ZLGw5lSwBNUcfZYxT80k4YLty 3dxUOAhSAjuXwF2ji6EHg54lUhj+w1g4SU1Nn/0SPt+Kl7IbpTPAFhVSiVJmb6gmCYCe LbWfO/ImEo0ogf+mutY2A8+ehsuCBYKPhocE00l7oqXOKo5b7hOIMhDTIYLKI59uYle/ OdLA== X-Gm-Message-State: AC+VfDyPUuzdc/emZXXgBbiNtV/JFPBnn2LFNnzv7J83PqiRsAak5kgG hUL9W+VbF4jekwZ1OSJMLYcFZQ== X-Google-Smtp-Source: ACHHUZ6ycnNF8Yd16rVGJYGcJx7BXDIL8yb88KqwcCKd5ph6scnPX3adlemcGYKPU680bLYJm4BkEA== X-Received: by 2002:a37:856:0:b0:75b:23a0:d9d5 with SMTP id 83-20020a370856000000b0075b23a0d9d5mr7619005qki.43.1684942373514; Wed, 24 May 2023 08:32:53 -0700 (PDT) Received: from joelboxx.c.googlers.com.com (129.239.188.35.bc.googleusercontent.com. [35.188.239.129]) by smtp.gmail.com with ESMTPSA id v18-20020a05620a123200b007590aa4b115sm3296906qkj.87.2023.05.24.08.32.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 May 2023 08:32:52 -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 v3 2/6] mm/mremap: Allow moves within the same VMA Date: Wed, 24 May 2023 15:32:35 +0000 Message-ID: <20230524153239.3036507-3-joel@joelfernandes.org> X-Mailer: git-send-email 2.40.1.698.g37aff9b760-goog In-Reply-To: <20230524153239.3036507-1-joel@joelfernandes.org> References: <20230524153239.3036507-1-joel@joelfernandes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org For the stack move happening in shift_arg_pages(), the move is happening within the same VMA which spans the old and new ranges. In case the aligned address happens to fall within that VMA, allow such moves and don't abort the optimization. In the mremap case, we cannot allow any such moves as will end up destroying some part of the mapping (either the source of the move, or part of the existing mapping). So just avoid it for mremap. Signed-off-by: Joel Fernandes (Google) --- fs/exec.c | 2 +- include/linux/mm.h | 2 +- mm/mremap.c | 40 ++++++++++++++++++++-------------------- 3 files changed, 22 insertions(+), 22 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 7c44d0c65b1b..7a7217353115 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -707,7 +707,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) * process cleanup to remove whatever mess we made. */ if (length != move_page_tables(vma, old_start, - vma, new_start, length, false)) + vma, new_start, length, false, true)) return -ENOMEM; lru_add_drain(); diff --git a/include/linux/mm.h b/include/linux/mm.h index 1f79667824eb..dd415cd2493d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2265,7 +2265,7 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen); extern 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, - bool need_rmap_locks); + bool need_rmap_locks, bool for_stack); /* * Flags used by change_protection(). For now we make it a bitmap so diff --git a/mm/mremap.c b/mm/mremap.c index 184d52f83b19..323c3b94216f 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -479,18 +479,23 @@ static bool move_pgt_entry(enum pgt_entry entry, struct vm_area_struct *vma, } /* - * 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. + * A helper to check if aligning down is OK. The aligned address should fall + * on *no mapping*. For the stack moving down, that's a special move within + * the VMA that is created to span the source and destination of the move, + * so we make an exception for it. */ static bool can_align_down(struct vm_area_struct *vma, unsigned long addr_to_align, - unsigned long mask) + unsigned long mask, bool for_stack) { unsigned long addr_masked = addr_to_align & mask; struct vm_area_struct *prev = NULL, *cur = NULL; - /* If the masked address is within vma, we cannot align the address down. */ - if (vma->vm_start <= addr_masked) + /* + * Other than for stack moves, if the alignment causes the address to be within + * its own @vma, we can't align down or we will destroy the current mapping. + * In other words for non-stack moves, the masked addr has to fall on no mapping. + */ + if (!for_stack && vma->vm_start <= addr_masked) return false; /* @@ -513,13 +518,13 @@ static bool can_align_down(struct vm_area_struct *vma, unsigned long addr_to_ali /* Opportunistically realign to specified boundary for faster copy. */ static void 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) + unsigned long mask, bool for_stack) { bool mutually_aligned = (*old_addr & ~mask) == (*new_addr & ~mask); if ((*old_addr & ~mask) && mutually_aligned - && can_align_down(old_vma, *old_addr, mask) - && can_align_down(new_vma, *new_addr, mask)) { + && can_align_down(old_vma, *old_addr, mask, for_stack) + && can_align_down(new_vma, *new_addr, mask, for_stack)) { *old_addr = *old_addr & mask; *new_addr = *new_addr & mask; } @@ -528,7 +533,7 @@ static void realign_addr(unsigned long *old_addr, struct vm_area_struct *old_vma 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, - bool need_rmap_locks) + bool need_rmap_locks, bool for_stack) { unsigned long extent, old_end; struct mmu_notifier_range range; @@ -540,14 +545,9 @@ unsigned long move_page_tables(struct vm_area_struct *vma, old_end = old_addr + len; - /* - * If possible, realign addresses to PMD boundary for faster copy. - * Don't align for intra-VMA moves as we may destroy existing mappings. - */ - if ((vma != new_vma) - && (len >= PMD_SIZE - (old_addr & ~PMD_MASK))) { - realign_addr(&old_addr, vma, &new_addr, new_vma, PMD_MASK); - } + /* If possible, realign addresses to PMD boundary for faster copy. */ + if (len >= PMD_SIZE - (old_addr & ~PMD_MASK)) + realign_addr(&old_addr, vma, &new_addr, new_vma, PMD_MASK, for_stack); if (is_vm_hugetlb_page(vma)) return move_hugetlb_page_tables(vma, new_vma, old_addr, @@ -696,7 +696,7 @@ static unsigned long move_vma(struct vm_area_struct *vma, } moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len, - need_rmap_locks); + need_rmap_locks, false); if (moved_len < old_len) { err = -ENOMEM; } else if (vma->vm_ops && vma->vm_ops->mremap) { @@ -710,7 +710,7 @@ static unsigned long move_vma(struct vm_area_struct *vma, * and then proceed to unmap new area instead of old. */ move_page_tables(new_vma, new_addr, vma, old_addr, moved_len, - true); + true, false); vma = new_vma; old_len = new_len; old_addr = new_addr; From patchwork Wed May 24 15:32:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 685533 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 C8AAEC77B73 for ; Wed, 24 May 2023 15:33:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235945AbjEXPdB (ORCPT ); Wed, 24 May 2023 11:33:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236035AbjEXPc7 (ORCPT ); Wed, 24 May 2023 11:32:59 -0400 Received: from mail-qv1-xf34.google.com (mail-qv1-xf34.google.com [IPv6:2607:f8b0:4864:20::f34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C21899 for ; Wed, 24 May 2023 08:32:57 -0700 (PDT) Received: by mail-qv1-xf34.google.com with SMTP id 6a1803df08f44-62383441211so5880146d6.0 for ; Wed, 24 May 2023 08:32:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1684942376; x=1687534376; 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=O0tjYXHW6XM/uedvUXhXTuxPHgCneWCEnRUXzUjK1Qc=; b=WXmStX11/lcotVWec4XBydhg1nwkR8cil5DVP3/cqlxA53iGKbBlq2LBmZ8kmIS4/r a42WEPdEz0veNSLGKQQUgS5H4SFzZ1A3H++srImE6xmN96tt9QD+wjWYUpBgUjbRleFp 6NoSUE5RS+7ygUhpinyFf0tBZWIFpnBydFpVc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684942376; x=1687534376; 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=O0tjYXHW6XM/uedvUXhXTuxPHgCneWCEnRUXzUjK1Qc=; b=J+ayk8xbheRhI03gMWq2NRTfc4vjzYjFnPXKhY4ZWpCU59U90AZnLQ0JzqMk8cobYf +SU82xRWr+6SyfArHNo5uASmGJmuaOTZ//Huj5I23ajObDD3wO+0Mj8yE+aibU7hBK64 9XIcBjtHHR8em73vDLzC28Ro6zWRkDB4R/M8gk7UDrodx//hSwtha2DirNM1zfodi2pS kSJRnvgE33qdmPOqPQiw220fvjY/rlZqLrTKJEnU8b2OQG+Up2Lv5xg1E+A95Cr4uhh4 l+LcXTCoxf1Xdwow6fAggoA3933qnlnCFgPx55kamyShBcsc1jcTQI1NNPSrH7hXp129 +axw== X-Gm-Message-State: AC+VfDwB6gwSOzTvJHYMO2CihAR8xYln3x6n6nGrnCIAXDp/zSAFbs0l YuDQED7E2/wBaMvl6NduSYuKFg== X-Google-Smtp-Source: ACHHUZ4AwVIelEKkuW8s2dK/dZksnx8tZkorF6LbPrQg4YdcjW4lVxTGTr5no8OzVcwrd3wM8+TwCw== X-Received: by 2002:ad4:5942:0:b0:623:86a9:7696 with SMTP id eo2-20020ad45942000000b0062386a97696mr23247464qvb.5.1684942376578; Wed, 24 May 2023 08:32:56 -0700 (PDT) Received: from joelboxx.c.googlers.com.com (129.239.188.35.bc.googleusercontent.com. [35.188.239.129]) by smtp.gmail.com with ESMTPSA id v18-20020a05620a123200b007590aa4b115sm3296906qkj.87.2023.05.24.08.32.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 May 2023 08:32:55 -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 v3 5/6] selftests: mm: Add a test for remapping to area immediately after existing mapping Date: Wed, 24 May 2023 15:32:38 +0000 Message-ID: <20230524153239.3036507-6-joel@joelfernandes.org> X-Mailer: git-send-email 2.40.1.698.g37aff9b760-goog In-Reply-To: <20230524153239.3036507-1-joel@joelfernandes.org> References: <20230524153239.3036507-1-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) --- 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"); /*