From patchwork Wed Apr 6 22:23:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiaqi Yan X-Patchwork-Id: 12804146 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 C4EC4C433F5 for ; Wed, 6 Apr 2022 22:24:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B1FB06B0073; Wed, 6 Apr 2022 18:24:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AD0436B0074; Wed, 6 Apr 2022 18:24:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 970526B0075; Wed, 6 Apr 2022 18:24:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0212.hostedemail.com [216.40.44.212]) by kanga.kvack.org (Postfix) with ESMTP id 898626B0073 for ; Wed, 6 Apr 2022 18:24:12 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 3C993ACB79 for ; Wed, 6 Apr 2022 22:24:02 +0000 (UTC) X-FDA: 79327883124.22.E93E633 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) by imf29.hostedemail.com (Postfix) with ESMTP id BEF3A120003 for ; Wed, 6 Apr 2022 22:24:01 +0000 (UTC) Received: by mail-pl1-f202.google.com with SMTP id w14-20020a1709027b8e00b0015386056d2bso1786695pll.5 for ; Wed, 06 Apr 2022 15:24:01 -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=ocQ4QiG6Z1H71mtTf4/Vzq9scVVfYbY83xjr/pOOFc4=; b=T+2tCxAeKmEiyZhdqMtu3r7WhPXDkViJJMNjkYn9+b++/9g3XrCUBjB1UF/m67dOOw YtMeufUsLkxIRyh/0YEa+XHbMTxrj09fik5ljSLKltIDOqMoM7oJTsmqlV1VzgOVJamU Cd7aLQiKOmxHJaAo1gTII9+3uiVV3rzkOwMLNf+uhMa66y/BA8b6HfmQZNUb4I0WU76b g6ASLi9uQeyahzcreJSC+rgsYEtqqKnGQXPbTOaMtp1Eo0zpXMWs1uHfYtPJSQsRDUOB /yL/odFRN2rZhgCwwkt35SZjGFlhJ18p6vbGLPWL0RYNlVEE8IUs40AIZJFQSRTdAexM P+jw== 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=ocQ4QiG6Z1H71mtTf4/Vzq9scVVfYbY83xjr/pOOFc4=; b=t/cEr8xwfAZ8w8NIRbUCuAYe8nwuut+UTuNTqUhppZEX2IHbSThk2qOx6p1QQmjUCH XsxcC1zeCriMHbJPR4o8WBNebR9cIgeobgSLCtwqMcXD6xq9WgdD4X5nhplNeyE/j96h vPzB3b4SF7qSv84sFxsA6xBixUKPW6k6XiDpJaFuOi72btVhC17diONjBp33G30PhO9v jECTzoxo4hhkuzMOTidNZdatSFvvAeRCxjHhWXiiNmGujEkJrchriQsWERV8bZ8TEKmO IYTg9YdbbuV/+WnaQ0XS+H9qD9Y+/aXICezVyO7qVM8h/GK2WzvQ1+pXQ674AG2hQsHj fESw== X-Gm-Message-State: AOAM531uijN35WV5ZKRDYgEYDpyjZ1Y8/TTlt6N6/RBVsG6AEueSF1JL cyiubZd2z1cWBGUk7oM4hvouL21OzBi4BQ== X-Google-Smtp-Source: ABdhPJzD2S+TsZ8bcpXuNQGAN5QqJb83dJQWLvPavNZHa7L6ALH4Nts6cVfrrx5vK6yI0KnFyfR4Pg4MkXm5yw== X-Received: from yjqkernel.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1837]) (user=jiaqiyan job=sendgmr) by 2002:a05:6a00:2311:b0:4e1:52bf:e466 with SMTP id h17-20020a056a00231100b004e152bfe466mr11124650pfh.77.1649283840746; Wed, 06 Apr 2022 15:24:00 -0700 (PDT) Date: Wed, 6 Apr 2022 15:23:50 -0700 In-Reply-To: <20220406222351.949927-1-jiaqiyan@google.com> Message-Id: <20220406222351.949927-2-jiaqiyan@google.com> Mime-Version: 1.0 References: <20220406222351.949927-1-jiaqiyan@google.com> X-Mailer: git-send-email 2.35.1.1178.g4f1659d476-goog Subject: [RFC v2 1/2] mm: khugepaged: recover from poisoned anonymous memory From: Jiaqi Yan To: shy828301@gmail.com, tongtiangen@huawei.com Cc: tony.luck@intel.com, naoya.horiguchi@nec.com, kirill.shutemov@linux.intel.com, linmiaohe@huawei.com, juew@google.com, linux-mm@kvack.org, Jiaqi Yan X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: BEF3A120003 X-Rspam-User: Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=T+2tCxAe; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf29.hostedemail.com: domain of 3ABNOYggKCHcedVldtVibjjbgZ.Xjhgdips-hhfqVXf.jmb@flex--jiaqiyan.bounces.google.com designates 209.85.214.202 as permitted sender) smtp.mailfrom=3ABNOYggKCHcedVldtVibjjbgZ.Xjhgdips-hhfqVXf.jmb@flex--jiaqiyan.bounces.google.com X-Stat-Signature: zrnsrz8x9fgbzcsriwh81mx1akhi8oa3 X-HE-Tag: 1649283841-905239 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 copying 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 | 138 ++++++++++++++++++++++++++++++---------- 2 files changed, 124 insertions(+), 33 deletions(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 39bb9b47fa9cd..0ccb1e92c4b06 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -298,6 +298,25 @@ static inline void copy_highpage(struct page *to, struct page *from) #endif +/* + * Machine check exception handled version of copy_highpage. + * Return true if copying page content failed; otherwise false. + * Note handling #MC requires arch opt-in. + */ +static inline bool copy_highpage_mc(struct page *to, struct page *from) +{ + 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; +} + static inline void memcpy_page(struct page *dst_page, size_t dst_off, struct page *src_page, size_t src_off, size_t len) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 131492fd1148b..8e69a0640e551 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -52,6 +52,7 @@ enum scan_result { SCAN_CGROUP_CHARGE_FAIL, SCAN_TRUNCATED, SCAN_PAGE_HAS_PRIVATE, + SCAN_COPY_MC, }; #define CREATE_TRACE_POINTS @@ -739,44 +740,98 @@ 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 copying succeeds; + * otherwise restore the original pmd page table. Returns true if copying + * succeeds, otherwise returns false. + * + * @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_highpage_mc(page, src_page)) { + 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 +839,8 @@ 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 +1123,7 @@ static void collapse_huge_page(struct mm_struct *mm, struct vm_area_struct *vma; struct mmu_notifier_range range; gfp_t gfp; + bool copied = false; VM_BUG_ON(address & ~HPAGE_PMD_MASK); @@ -1177,9 +1235,13 @@ 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); + copied = __collapse_huge_page_copy(pte, new_page, pmd, _pmd, + vma, address, pte_ptl, &compound_pagelist); pte_unmap(pte); + if (!copied) { + result = SCAN_COPY_MC; + 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 +1426,14 @@ 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 +2235,11 @@ 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);