From patchwork Wed Mar 23 23:29:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiaqi Yan X-Patchwork-Id: 12790257 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2C2BC433F5 for ; Wed, 23 Mar 2022 23:29:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6A7ED6B0073; Wed, 23 Mar 2022 19:29:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 67D316B0074; Wed, 23 Mar 2022 19:29:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4F84B6B0075; Wed, 23 Mar 2022 19:29:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0080.hostedemail.com [216.40.44.80]) by kanga.kvack.org (Postfix) with ESMTP id 3EDF16B0073 for ; Wed, 23 Mar 2022 19:29:56 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id E687D8249980 for ; Wed, 23 Mar 2022 23:29:55 +0000 (UTC) X-FDA: 79277245950.22.5DBA7CA Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) by imf04.hostedemail.com (Postfix) with ESMTP id 5FB834000A for ; Wed, 23 Mar 2022 23:29:55 +0000 (UTC) Received: by mail-pl1-f202.google.com with SMTP id p5-20020a1709028a8500b0015382b21b58so1547494plo.19 for ; Wed, 23 Mar 2022 16:29:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=ZZQr0FtN49nhyDRQ0Gluc9tLxpVc6O8LFwq/EKt1Sqo=; b=i61Q2cBpgrA9Lil8FQ//1ZcL2+Uz7MBOjxtTMqn+iSh5LjAvSvQHkS08fQmC/6peT1 a0J4cJyhZQfgeTUdAmV7a90LjgivS1vDoYCkIkeT97MYZ9XAhIIZFk/nYblkxADygB0q XHGlbEqvYz0iRg8P07HW9LswZoaTtas9hh2TwbLI7LFdljkeb10pMo95nypdNCYmXJD4 F6x7p5R49Aj3jbdwjDxbB1iN03g5VVCTKMi8nE3mmVvWF/bijIskN9owDQscU+bapIfS Xw0bt++1ait2YPGEU+Y24lGleneb1Qah1RykeH4svSfLrvChJ6YtNQO4PqYb7AZ1zStQ TdRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=ZZQr0FtN49nhyDRQ0Gluc9tLxpVc6O8LFwq/EKt1Sqo=; b=v1aGkasALGW6Iq0x33W9rAHhOWotvhrgSEb+BgtgjqyoSkBqvlN2iXdoKqBXikL20V KXnjkFb0BH0acx/ursptHONgex1OoKlZaJrqvdWK3kxBqszXWyOUp88Q04sfLfLMnHDO Tz2ekjMQLj/3qbSJIudx0X6eERsYgvUhHV0yTBLDoP3MKV/I6LJ1gt7CQw0IRYVgGvQt w08tSizaX6I+w6RFgW5bdsTA9N/nKoV4NFa/0csgFlgDjtJABJJ04i3watNHbRpNo+nW jhFZbpo7wjvOi2x82MGQHwq6Z1TVHqH0GMWewzfHHTfuksWY7h2EGMGbs/mC5RI+swWl eSag== X-Gm-Message-State: AOAM5315CgauKZxqdlk3YU/H7EwhR8+aznuasuIdhCtT89QHbX/Lm52v DKQsoXngsH30GEM/BdSK1mvAurQurHujtQ== X-Google-Smtp-Source: ABdhPJzJfMccTms5tr17jYOxH6XJTYaKAkN4H6fFdh+MQuZQhEHwlJ1AJ+cgTKfJnCEzSP4ICilQCfi4BkXVzA== X-Received: from yjqkernel.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1837]) (user=jiaqiyan job=sendgmr) by 2002:a05:6a00:889:b0:4e0:dcc3:5e06 with SMTP id q9-20020a056a00088900b004e0dcc35e06mr1924183pfj.29.1648078194444; Wed, 23 Mar 2022 16:29:54 -0700 (PDT) Date: Wed, 23 Mar 2022 23:29:28 +0000 In-Reply-To: <20220323232929.3035443-1-jiaqiyan@google.com> Message-Id: <20220323232929.3035443-2-jiaqiyan@google.com> Mime-Version: 1.0 References: <20220323232929.3035443-1-jiaqiyan@google.com> X-Mailer: git-send-email 2.35.1.894.gb6a874cedc-goog Subject: [RFC v1 1/2] mm: khugepaged: recover from poisoned anonymous memory From: Jiaqi Yan To: shy828301@gmail.com Cc: tony.luck@intel.com, naoya.horiguchi@nec.com, kirill.shutemov@linux.intel.com, linmiaohe@huawei.com, juew@google.com, jiaqiyan@google.com, linux-mm@kvack.org X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5FB834000A X-Rspam-User: Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=i61Q2cBp; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf04.hostedemail.com: domain of 3cq07YggKCNM87zF7NzC5DD5A3.1DBA7CJM-BB9Kz19.DG5@flex--jiaqiyan.bounces.google.com designates 209.85.214.202 as permitted sender) smtp.mailfrom=3cq07YggKCNM87zF7NzC5DD5A3.1DBA7CJM-BB9Kz19.DG5@flex--jiaqiyan.bounces.google.com X-Stat-Signature: fdff5mzsebn57dytgwkiy8554d15o3ge X-HE-Tag: 1648078195-673526 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Make __collapse_huge_page_copy return whether collapsing/copying anonymous pages succeeded, and make collapse_huge_page handle the return status. Break existing PTE scan loop into two for-loops. The first loop copies source pages into target huge page, and can fail gracefully when running into memory errors in source pages. Roll back the page table and page states in the 2nd loop when copy failed: 1) re-establish the PTEs-to-PMD connection. 2) release pages back to their LRU list. Signed-off-by: Jiaqi Yan --- include/linux/highmem.h | 19 ++++++ mm/khugepaged.c | 136 ++++++++++++++++++++++++++++++---------- 2 files changed, 122 insertions(+), 33 deletions(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 39bb9b47fa9c..15d0aa4d349c 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -281,6 +281,25 @@ static inline void copy_user_highpage(struct page *to, struct page *from, kunmap_local(vfrom); } +/* + * Machine check exception handled version of copy_user_highpage. + * Return true if copying page content failed; otherwise false. + */ +static inline bool copy_user_highpage_mc(struct page *to, struct page *from, + unsigned long vaddr, struct vm_area_struct *vma) +{ + char *vfrom, *vto; + unsigned long ret; + + vfrom = kmap_local_page(from); + vto = kmap_local_page(to); + ret = copy_mc_to_kernel(vto, vfrom, PAGE_SIZE); + kunmap_local(vto); + kunmap_local(vfrom); + + return ret > 0; +} + #endif #ifndef __HAVE_ARCH_COPY_HIGHPAGE diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 131492fd1148..84ed177f56ff 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -739,44 +739,97 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, return 0; } -static void __collapse_huge_page_copy(pte_t *pte, struct page *page, - struct vm_area_struct *vma, - unsigned long address, - spinlock_t *ptl, - struct list_head *compound_pagelist) +/* + * __collapse_huge_page_copy - attempts to copy memory contents from normal + * pages to a hugepage. Cleanup the normal pages if copy succeeds; + * otherwise restore the original pmd page table. + * + * @pte: starting of the PTEs to copy from + * @page: the new hugepage to copy contents to + * @pmd: pointer to the new hugepage's PMD + * @rollback: the original normal PTEs' PMD + * @address: starting address to copy + * @pte_ptl: lock on normal pages' PTEs + * @compound_pagelist: list that stores compound pages + */ +static bool __collapse_huge_page_copy(pte_t *pte, + struct page *page, + pmd_t *pmd, + pmd_t rollback, + struct vm_area_struct *vma, + unsigned long address, + spinlock_t *pte_ptl, + struct list_head *compound_pagelist) { struct page *src_page, *tmp; pte_t *_pte; - for (_pte = pte; _pte < pte + HPAGE_PMD_NR; - _pte++, page++, address += PAGE_SIZE) { - pte_t pteval = *_pte; + pte_t pteval; + unsigned long _address; + spinlock_t *pmd_ptl; + bool copy_succeeded = true; - if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { + /* + * Copying pages' contents is subject to memory poison at any iteration. + */ + for (_pte = pte, _address = address; + _pte < pte + HPAGE_PMD_NR; + _pte++, page++, _address += PAGE_SIZE) { + pteval = *_pte; + + if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) clear_user_highpage(page, address); - add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); - if (is_zero_pfn(pte_pfn(pteval))) { - /* - * ptl mostly unnecessary. - */ - spin_lock(ptl); - ptep_clear(vma->vm_mm, address, _pte); - spin_unlock(ptl); + else { + src_page = pte_page(pteval); + if (copy_user_highpage_mc(page, src_page, address, vma)) { + copy_succeeded = false; + break; + } + } + } + + if (!copy_succeeded) { + /* + * Copying failed, re-establish the regular PMD that + * points to regular page table. Since PTEs are still + * isolated and locked, acquiring anon_vma_lock is unnecessary. + */ + pmd_ptl = pmd_lock(vma->vm_mm, pmd); + pmd_populate(vma->vm_mm, pmd, pmd_pgtable(rollback)); + spin_unlock(pmd_ptl); + } + + for (_pte = pte, _address = address; _pte < pte + HPAGE_PMD_NR; + _pte++, _address += PAGE_SIZE) { + pteval = *_pte; + if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { + if (copy_succeeded) { + add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); + if (is_zero_pfn(pte_pfn(pteval))) { + /* + * ptl mostly unnecessary. + */ + spin_lock(pte_ptl); + pte_clear(vma->vm_mm, _address, _pte); + spin_unlock(pte_ptl); + } } } else { src_page = pte_page(pteval); - copy_user_highpage(page, src_page, address, vma); if (!PageCompound(src_page)) release_pte_page(src_page); - /* - * ptl mostly unnecessary, but preempt has to - * be disabled to update the per-cpu stats - * inside page_remove_rmap(). - */ - spin_lock(ptl); - ptep_clear(vma->vm_mm, address, _pte); - page_remove_rmap(src_page, false); - spin_unlock(ptl); - free_page_and_swap_cache(src_page); + + if (copy_succeeded) { + /* + * ptl mostly unnecessary, but preempt has to + * be disabled to update the per-cpu stats + * inside page_remove_rmap(). + */ + spin_lock(pte_ptl); + pte_clear(vma->vm_mm, _address, _pte); + page_remove_rmap(src_page, false); + spin_unlock(pte_ptl); + free_page_and_swap_cache(src_page); + } } } @@ -784,6 +837,8 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page, list_del(&src_page->lru); release_pte_page(src_page); } + + return copy_succeeded; } static void khugepaged_alloc_sleep(void) @@ -1066,6 +1121,7 @@ static void collapse_huge_page(struct mm_struct *mm, struct vm_area_struct *vma; struct mmu_notifier_range range; gfp_t gfp; + bool copy_succeeded = false; VM_BUG_ON(address & ~HPAGE_PMD_MASK); @@ -1177,9 +1233,13 @@ static void collapse_huge_page(struct mm_struct *mm, */ anon_vma_unlock_write(vma->anon_vma); - __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl, - &compound_pagelist); + copy_succeeded = __collapse_huge_page_copy(pte, new_page, pmd, _pmd, + vma, address, pte_ptl, &compound_pagelist); pte_unmap(pte); + if (!copy_succeeded) { + result = SCAN_FAIL; + goto out_up_write; + } /* * spin_lock() below is not the equivalent of smp_wmb(), but * the smp_wmb() inside __SetPageUptodate() can be reused to @@ -1364,9 +1424,14 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, pte_unmap_unlock(pte, ptl); if (ret) { node = khugepaged_find_target_node(); - /* collapse_huge_page will return with the mmap_lock released */ - collapse_huge_page(mm, address, hpage, node, - referenced, unmapped); + /* + * collapse_huge_page will return with the mmap_r+w_lock released. + * It is uncertain if *hpage is NULL or not when collapse_huge_page + * returns, so keep ret=1 to jump to breakouterloop_mmap_lock + * in khugepaged_scan_mm_slot, then *hpage will be freed + * if collapse failed. + */ + collapse_huge_page(mm, address, hpage, node, referenced, unmapped); } out: trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, @@ -2168,6 +2233,11 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, khugepaged_scan_file(mm, file, pgoff, hpage); fput(file); } else { + /* + * mmap_read_lock is + * 1) released if both scan and collapse succeeded; + * 2) still held if either scan or collapse failed. + */ ret = khugepaged_scan_pmd(mm, vma, khugepaged_scan.address, hpage);