From patchwork Thu May 18 02:18:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 684172 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 A9861C77B75 for ; Thu, 18 May 2023 02:18:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229834AbjERCSr (ORCPT ); Wed, 17 May 2023 22:18:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229816AbjERCSq (ORCPT ); Wed, 17 May 2023 22:18:46 -0400 Received: from mail-qv1-xf33.google.com (mail-qv1-xf33.google.com [IPv6:2607:f8b0:4864:20::f33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BDB922139 for ; Wed, 17 May 2023 19:18:45 -0700 (PDT) Received: by mail-qv1-xf33.google.com with SMTP id 6a1803df08f44-6238daae378so2863106d6.1 for ; Wed, 17 May 2023 19:18:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1684376325; x=1686968325; 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=sKe+AGy/Knc6S6d8Do5DN/gqM9Uy00SAbxH28Kp1LUQ=; b=gpiRUjEC25YrRlvGt299DCLZarxkVMlPppBRMeGjpsXJgixg9Mf1V9AuFtBCGh5WIO zYyRiKyN25sNF/Dcpz8SONWOiUN5ginUd3c7nz+IsRYtc1emCT1YYGJXOzWz7hQjxiRf eGy+COuTrQdS11tlfAZg8TDkFkoBJhCtLoMlI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684376325; x=1686968325; 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=sKe+AGy/Knc6S6d8Do5DN/gqM9Uy00SAbxH28Kp1LUQ=; b=Bztokf+hCZ2xpAqc9C7DXtwiYf2rBfu0YkdunrGiUDAOQt5xN4E25xBMEMyXSIHLI0 1skxuSEvPT/tS9U4osQ7ShApezMpdw0+DvcBcokvgwiVN2trVOKynlNesVB1Fz0y9Wxs OZTOgPylxRY9iKU1rJS835T8kkAtPSs/ypYgyZ6eIJjDxhIQ3CeByVWLpJvuIJtC/9gK IAnBV2x64pm0ZksgdMYRCp3r84Sk7Z40tkGkIHAUS5cvx0riuLWpynRtJHIDtJldK+NX 5BMVABGOI8fPtP4G78Yss/JcX2aaZ4ZiuPhI6Ioi5kcz52gVnFmDU2+R5pW6U1Y8bjMk 8USw== X-Gm-Message-State: AC+VfDzfjo0atrTJylxfg1Lmo3lLgA2GO3Juxv1hxr/fJ0875BdUllGx iOLLYxXA/R1s3uF2KP49lCYPMg== X-Google-Smtp-Source: ACHHUZ777yYcb28ukvf7wMe6arbQau3nQ7xByk5Y74MW/Ag+xPWbEEnjrqrm1N1GiSy28LtIBX+nRg== X-Received: by 2002:a05:6214:2349:b0:5e8:3496:e641 with SMTP id hu9-20020a056214234900b005e83496e641mr2657341qvb.13.1684376324809; Wed, 17 May 2023 19:18:44 -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 j13-20020a05620a000d00b007577ccf566asm85082qki.93.2023.05.17.19.18.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 May 2023 19:18:44 -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" Subject: [PATCH RFC 1/4] mm/mremap: Optimize the start addresses in move_page_tables() Date: Thu, 18 May 2023 02:18:22 +0000 Message-ID: <20230518021825.712742-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.40.1.606.ga4b1b128d6-goog In-Reply-To: <20230518021825.712742-1-joel@joelfernandes.org> References: <20230518021825.712742-1-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/destination. 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. [1] https://lore.kernel.org/all/ZB2GTBD%2FLWTrkOiO@dhcp22.suse.cz/ [2] https://lore.kernel.org/all/CAHk-=whd7msp8reJPfeGNyt0LiySMT0egExx3TVZSX3Ok6X=9g@mail.gmail.com/ Signed-off-by: Joel Fernandes (Google) --- mm/mremap.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/mm/mremap.c b/mm/mremap.c index 411a85682b58..d7ee3b20e170 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -478,6 +478,51 @@ 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 check_addr_in_prev(struct vm_area_struct *vma, unsigned long addr, + unsigned long mask) +{ + int addr_masked = addr & mask; + struct vm_area_struct *prev = NULL, *cur = NULL; + + /* If the masked address is within vma, there is no prev mapping of concern. */ + if (vma->vm_start <= addr_masked) + return false; + + /* + * Attempt to find vma before prev that contains the address. + * On any issue, assume the address is within a previous mapping. + * @mmap write lock is held here, so the lookup is safe. + */ + cur = find_vma_prev(vma->vm_mm, vma->vm_start, &prev); + if (!cur || cur != vma || !prev) + return true; + + /* The masked address fell within a previous mapping. */ + if (prev->vm_end > addr_masked) + return true; + + return false; +} + +/* 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) +{ + if ((*old_addr & ~mask) && + (*old_addr & ~mask) == (*new_addr & ~mask) && + !check_addr_in_prev(old_vma, *old_addr, mask) && + !check_addr_in_prev(new_vma, *new_addr, mask)) { + *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, @@ -493,6 +538,10 @@ 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. */ + if (len >= PMD_SIZE) + realign_addr(&old_addr, vma, &new_addr, new_vma, PMD_MASK); + if (is_vm_hugetlb_page(vma)) return move_hugetlb_page_tables(vma, new_vma, old_addr, new_addr, len); From patchwork Thu May 18 02:18:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 683779 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 73E93C77B75 for ; Thu, 18 May 2023 02:19:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229852AbjERCTB (ORCPT ); Wed, 17 May 2023 22:19:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56050 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229835AbjERCSr (ORCPT ); Wed, 17 May 2023 22:18:47 -0400 Received: from mail-qt1-x82e.google.com (mail-qt1-x82e.google.com [IPv6:2607:f8b0:4864:20::82e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE1492137 for ; Wed, 17 May 2023 19:18:46 -0700 (PDT) Received: by mail-qt1-x82e.google.com with SMTP id d75a77b69052e-3f3882a5f8aso3757771cf.1 for ; Wed, 17 May 2023 19:18:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1684376326; x=1686968326; 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=RjDDJEmMByrSrRAzAnrYD81CTFNgsqIfOqapJ9IGu5M=; b=mQQrGh4h/KNWIK2PoMB6Pztwf3cVCXmBMz0qqgOhBsvYUoYmvpqwqduJIzlAMMC7YK ZrUS/hiBuG72PkbcadbIrnygdqpWVUoSGwOt1fIX6LFaYv2ZtLweuzoryGI5e/lbAEvj QAZwZXY/iYOPxIXmup+iJ05KpzCFPd+H+MV7k= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684376326; x=1686968326; 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=RjDDJEmMByrSrRAzAnrYD81CTFNgsqIfOqapJ9IGu5M=; b=cy4c4a51tBfGhGLUYm0N8FSIF3To+ro4pxNkrqywy+I4elIY3H9z2fDQSfjsDL5WDV 9Z+zRWzOfbJWVTUNfZOW2Rz3f/dcj4qBF3l1x0MwwyUMJk938yaFheFEZ/xBd5yxLWoY 5vjfkTnum/0FwNnuKJoDktq6MZ1LvEYh5FTsACrHhtVxDG8BjKj5ulV9ixUC5uwaadgP FJiDPGxrUUhmNo9W5YXjKhmIgjzGez0ws90h7wUvPWmbQIKgcE8TvPv/lWkmLPPLvrN8 BMT+rnxvPYJ/HH84+cqFEmeUO94GO6UsUxPAQF+b5I9QIrFQwXnuSFSaV2U75OfRvN2W Grog== X-Gm-Message-State: AC+VfDyCb0AdC688ATaB1BaRx90+dP14Oxh8fevHe5ZFLm1uMv2v+Oqf KX7SkqsEwAFV3kubvwppO96U5g== X-Google-Smtp-Source: ACHHUZ7onnyA0YRXFWFSrDrQsTcQvuLRzQPOgD7sBT31Y/nwpybDDjLCC9uzwGCwdRjZeUxjOoHbXw== X-Received: by 2002:ac8:588f:0:b0:3f5:2fa4:43bd with SMTP id t15-20020ac8588f000000b003f52fa443bdmr3399132qta.3.1684376325860; Wed, 17 May 2023 19:18:45 -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 j13-20020a05620a000d00b007577ccf566asm85082qki.93.2023.05.17.19.18.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 May 2023 19:18:45 -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" Subject: [PATCH RFC 2/4] selftests: mm: Fix failure case when new remap region was not found Date: Thu, 18 May 2023 02:18:23 +0000 Message-ID: <20230518021825.712742-3-joel@joelfernandes.org> X-Mailer: git-send-email 2.40.1.606.ga4b1b128d6-goog In-Reply-To: <20230518021825.712742-1-joel@joelfernandes.org> References: <20230518021825.712742-1-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) --- 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 Thu May 18 02:18:24 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 684171 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 797B0C7EE2C for ; Thu, 18 May 2023 02:19:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229869AbjERCTA (ORCPT ); Wed, 17 May 2023 22:19:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229852AbjERCSs (ORCPT ); Wed, 17 May 2023 22:18:48 -0400 Received: from mail-qk1-x72d.google.com (mail-qk1-x72d.google.com [IPv6:2607:f8b0:4864:20::72d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7852D2139 for ; Wed, 17 May 2023 19:18:47 -0700 (PDT) Received: by mail-qk1-x72d.google.com with SMTP id af79cd13be357-7590aa05af6so170730485a.0 for ; Wed, 17 May 2023 19:18:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1684376326; x=1686968326; 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=O+pMaJ78vDhX/WJumeumdh2Ew8rPwZqh+d939UbVmCI=; b=laThT9KmuWwvZ+2Yoy5xsTan07ApYzz/BleFpSz8wK9Si/Q7ltWEJAFVbUqtOZ4D6L TMd2/Y9xWpgxsYsAa9xV49mMbN1y6fwgjT/pKe1dU8Islleu93aNaPSMOLxKyhX/jNrJ 4p5p9XM83q3qupRwXWj+wCh1LxpyNLzARQFWk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684376326; x=1686968326; 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=O+pMaJ78vDhX/WJumeumdh2Ew8rPwZqh+d939UbVmCI=; b=DVKTFSJ7nD7k5RZCq4cE6FM/X10XxvlG9hJoLOtyer3MuL830XUxPtBl8sjoLscK2n mwjWQMlxTsPXEHF8S/rrMtqKGMYIPO8Blfl6idBQP9YWrNyGhts4SSsh0tRHUyqCD17D ANCz5LinmHM5B/mx+bQNzAhBs8o4QU9J+gKavYDEb/5aPmvhzr9uZnoBgaaWMl+gtAYz cPZNoyO9IP4fJRVKcJsFiSm2VF8lT3NUpIdayHJMdSBYk8PsYEjMvMo02FzepBRpa8jZ qf/RE8xcVriFtqePZTqJ3hTF8Gkbu2B5tDr3pGXOuK2dZYLXUbERVmjuvIlz4XuX289A lAwQ== X-Gm-Message-State: AC+VfDwwlPSFIGDYwGZZTa9buEw7o9/49v7Nmc1OUwXN3ZXgQZR1+WDh V/uX4f1X+XS0BS1f9nTk4xeOYQ== X-Google-Smtp-Source: ACHHUZ6UnCuj5Nq3VC1ze3Rr3HeldoNEZzJlJJp6jYqyiOJjllcKquWS6RDoPMf5upFCbGWuS1xJyg== X-Received: by 2002:ac8:59cf:0:b0:3f5:315f:5c19 with SMTP id f15-20020ac859cf000000b003f5315f5c19mr3147223qtf.62.1684376326582; Wed, 17 May 2023 19:18:46 -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 j13-20020a05620a000d00b007577ccf566asm85082qki.93.2023.05.17.19.18.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 May 2023 19:18:46 -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" Subject: [PATCH RFC 3/4] selftests: mm: Add a test for mutually aligned moves > PMD size Date: Thu, 18 May 2023 02:18:24 +0000 Message-ID: <20230518021825.712742-4-joel@joelfernandes.org> X-Mailer: git-send-email 2.40.1.606.ga4b1b128d6-goog In-Reply-To: <20230518021825.712742-1-joel@joelfernandes.org> References: <20230518021825.712742-1-joel@joelfernandes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org This patch adds a test case to check if a PMD-alignment optimization successfully happens. I add support to make sure there is some room before the source mapping, otherwise the optimization to trigger PMD-aligned move will be disabled as the kernel will detect that a mapping before the source exists and such optimization becomes impossible. Signed-off-by: Joel Fernandes (Google) --- tools/testing/selftests/mm/mremap_test.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/mm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c index 6822d657f589..6304eb0947a3 100644 --- a/tools/testing/selftests/mm/mremap_test.c +++ b/tools/testing/selftests/mm/mremap_test.c @@ -44,6 +44,7 @@ enum { _1MB = 1ULL << 20, _2MB = 2ULL << 20, _4MB = 4ULL << 20, + _5MB = 5ULL << 20, _1GB = 1ULL << 30, _2GB = 2ULL << 30, PMD = _2MB, @@ -235,6 +236,11 @@ static void *get_source_mapping(struct config c) 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; @@ -434,7 +440,7 @@ static int parse_args(int argc, char **argv, unsigned int *threshold_mb, return 0; } -#define MAX_TEST 13 +#define MAX_TEST 14 #define MAX_PERF_TEST 3 int main(int argc, char **argv) { @@ -500,6 +506,10 @@ int main(int argc, char **argv) test_cases[12] = MAKE_TEST(PUD, PUD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS, "2GB mremap - Source PUD-aligned, Destination PUD-aligned"); + /* Src and Dest addr 1MB aligned. 5MB mremap. */ + test_cases[13] = MAKE_TEST(_1MB, _1MB, _5MB, NON_OVERLAPPING, EXPECT_SUCCESS, + "5MB mremap - Source 1MB-aligned, Destination 1MB-aligned"); + 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 Thu May 18 02:18:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 683780 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 31D90C77B7F for ; Thu, 18 May 2023 02:19:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229810AbjERCSz (ORCPT ); Wed, 17 May 2023 22:18:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229867AbjERCSt (ORCPT ); Wed, 17 May 2023 22:18:49 -0400 Received: from mail-qk1-x729.google.com (mail-qk1-x729.google.com [IPv6:2607:f8b0:4864:20::729]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6CFF3268A for ; Wed, 17 May 2023 19:18:48 -0700 (PDT) Received: by mail-qk1-x729.google.com with SMTP id af79cd13be357-7575fc62c7aso156703185a.0 for ; Wed, 17 May 2023 19:18:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1684376327; x=1686968327; 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=tGuemAvtIS/ALPtC/Ke2yJXoSr37KqjSOh21F52Z0b4=; b=XjEWVFgjHhBSgx+JzMuzHzMuMMrg6ZCjBCCAdXf//YzfKBHsPOaTSvveyrxyVc63mB OszLdP5qzb0tPw+Ax1TNz+UB1DuNFET/RCjILS/7u5bCzvBBR1KOj19dWdhgLKcgBzef NYJtJv4KZejE9EsPY58w3IzlHS7ZNhsiLoXuY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684376327; x=1686968327; 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=tGuemAvtIS/ALPtC/Ke2yJXoSr37KqjSOh21F52Z0b4=; b=Vo1ePpI/fr9BuU5nORhy1AaA7A7GMPvHVLNeX6HhSpTCgXMj5osl9opaOUNtuta69r UpmuYnGLesBxB769OO7L3ORrHhMPE0vGIZ5V/ifDEsfSHivozRHijA/YZI/3ndWQ8Gl+ 2knwkixkNvsbeGV3x3dfBuhKhFfoD3iqna9ud2WZ2JS8kqwo8nege4RE9xJlWEcT8Ft5 Uyk730r0wNWLyjI7lPmxidlDQcxznCzT+2U+8//w25GiJCtcSZK3KQFxGQNuZwqmPkP6 WyQT/L6UzDUcBHB/7KZinTtaynFVA8fVhpQ/jDknjoGQlTrau9atZu1c+ZUE52hp6Jpr Hogw== X-Gm-Message-State: AC+VfDwdVMeA+8lw0y35dflNWS70rdLbwVpaYOKLxpZ0wabl8fjUwh67 tZ015dfG3s9bjNfye9ULOVv43g== X-Google-Smtp-Source: ACHHUZ4YcOJzn6aoVPNard/VpdQHjhpKxZ/STCMnHfkC5tH5L1a/155XBb4RZDt8EkvRYuJwqaMCWA== X-Received: by 2002:a05:622a:1d0:b0:3ef:366b:5afa with SMTP id t16-20020a05622a01d000b003ef366b5afamr3403956qtw.54.1684376327485; Wed, 17 May 2023 19:18:47 -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 j13-20020a05620a000d00b007577ccf566asm85082qki.93.2023.05.17.19.18.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 May 2023 19:18:46 -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" Subject: [PATCH RFC 4/4] selftests: mm: Add a test for remapping to area immediately after existing mapping Date: Thu, 18 May 2023 02:18:25 +0000 Message-ID: <20230518021825.712742-5-joel@joelfernandes.org> X-Mailer: git-send-email 2.40.1.606.ga4b1b128d6-goog In-Reply-To: <20230518021825.712742-1-joel@joelfernandes.org> References: <20230518021825.712742-1-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). check_addr_in_prev(old_vma->vm_start=2900000, old_addr=2900000, mask=-2097152): 0 check_addr_in_prev(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 check_addr_in_prev() returns 1 for the destination mapping as we detected there is something there. check_addr_in_prev(old_vma->vm_start=2900000, old_addr=2900000, mask=-2097152): 0 check_addr_in_prev(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"); /*