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Sun, 06 Nov 2022 18:54:04 -0800 (PST) Date: Sun, 6 Nov 2022 18:53:58 -0800 In-Reply-To: <20221107025359.2911028-1-jiaqiyan@google.com> Mime-Version: 1.0 References: <20221107025359.2911028-1-jiaqiyan@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221107025359.2911028-2-jiaqiyan@google.com> Subject: [PATCH v6 1/2] mm/khugepaged: recover from poisoned anonymous memory From: Jiaqi Yan To: kirill.shutemov@linux.intel.com, kirill@shutemov.name, shy828301@gmail.com, tongtiangen@huawei.com Cc: tony.luck@intel.com, naoya.horiguchi@nec.com, linmiaohe@huawei.com, jiaqiyan@google.com, linux-mm@kvack.org, akpm@linux-foundation.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667789646; a=rsa-sha256; cv=none; b=JtY/06Ns1+aRA0YwUmHvLmDEhk65f2ftStjgzWhyddCzdyGG+1SfLEPpWe7Zx1zjzwi78r KNejqbSMt7wMPvqNEUrRe/bhGvHGaWfQ82fdb8gDNetUwUG8LqtiECs6YP4Znph+UkSA6T grertGUHKkzwKx17OjK46pX1hxni+hQ= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b="tKID9n/m"; 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spf=pass (imf04.hostedemail.com: domain of 3THNoYwgKCPUgfXnfvXkdlldib.Zljifkru-jjhsXZh.lod@flex--jiaqiyan.bounces.google.com designates 209.85.214.202 as permitted sender) smtp.mailfrom=3THNoYwgKCPUgfXnfvXkdlldib.Zljifkru-jjhsXZh.lod@flex--jiaqiyan.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 1A40540003 X-Stat-Signature: p4ditn8ufdp1fzb4wtnhtxc1ith5fi1z X-HE-Tag: 1667789645-622678 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 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. If copying all pages succeeds, the second loop releases and clears up these normal pages. Otherwise, the second loop rolls back the page table and page states by: - re-establishing the original PTEs-to-PMD connection. - releasing source pages back to their LRU list. Tested manually: 0. Enable khugepaged on system under test. 1. Start a two-thread application. Each thread allocates a chunk of non-huge anonymous memory buffer. 2. Pick 4 random buffer locations (2 in each thread) and inject uncorrectable memory errors at corresponding physical addresses. 3. Signal both threads to make their memory buffer collapsible, i.e. calling madvise(MADV_HUGEPAGE). 4. Wait and check kernel log: khugepaged is able to recover from poisoned pages and skips collapsing them. 5. Signal both threads to inspect their buffer contents and make sure no data corruption. Signed-off-by: Jiaqi Yan --- include/linux/highmem.h | 19 ++++ include/trace/events/huge_memory.h | 3 +- mm/khugepaged.c | 159 +++++++++++++++++++++-------- 3 files changed, 138 insertions(+), 43 deletions(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 44242268f53bd..bcd317998e4bb 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -361,6 +361,25 @@ 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/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h index 35d759d3b0104..5743ae970af31 100644 --- a/include/trace/events/huge_memory.h +++ b/include/trace/events/huge_memory.h @@ -36,7 +36,8 @@ EM( SCAN_ALLOC_HUGE_PAGE_FAIL, "alloc_huge_page_failed") \ EM( SCAN_CGROUP_CHARGE_FAIL, "ccgroup_charge_failed") \ EM( SCAN_TRUNCATED, "truncated") \ - EMe(SCAN_PAGE_HAS_PRIVATE, "page_has_private") \ + EM( SCAN_PAGE_HAS_PRIVATE, "page_has_private") \ + EMe(SCAN_COPY_MC, "copy_poisoned_page") \ #undef EM #undef EMe diff --git a/mm/khugepaged.c b/mm/khugepaged.c index ea0d186bc9d4c..c1f225327bc05 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -55,6 +55,7 @@ enum scan_result { SCAN_CGROUP_CHARGE_FAIL, SCAN_TRUNCATED, SCAN_PAGE_HAS_PRIVATE, + SCAN_COPY_MC, }; #define CREATE_TRACE_POINTS @@ -670,56 +671,125 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, return result; } -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 page table and release isolated normal pages. + * 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 pages' PMD + * @vma: the original normal pages' virtual memory area + * @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))) { - clear_user_highpage(page, address); - add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); - if (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); + else { + src_page = pte_page(pteval); + if (copy_highpage_mc(page, src_page)) { + copy_succeeded = false; + break; + } + } + } + + if (copy_succeeded) { + 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))) { + add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); + if (is_zero_pfn(pte_pfn(pteval))) { + /* + * pte_ptl mostly unnecessary. + */ + spin_lock(pte_ptl); + pte_clear(vma->vm_mm, _address, _pte); + spin_unlock(pte_ptl); + } + } else { + src_page = pte_page(pteval); + if (!PageCompound(src_page)) + release_pte_page(src_page); /* - * ptl mostly unnecessary. + * pte_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); - spin_unlock(ptl); + spin_lock(pte_ptl); + ptep_clear(vma->vm_mm, _address, _pte); + page_remove_rmap(src_page, vma, false); + spin_unlock(pte_ptl); + free_page_and_swap_cache(src_page); } - } 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, vma, false); - spin_unlock(ptl); - free_page_and_swap_cache(src_page); + } + list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) { + list_del(&src_page->lru); + mod_node_page_state(page_pgdat(src_page), + NR_ISOLATED_ANON + page_is_file_lru(src_page), + -compound_nr(src_page)); + unlock_page(src_page); + free_swap_cache(src_page); + putback_lru_page(src_page); + } + } else { + /* + * Re-establish the regular PMD that points to the regular + * page table. Restoring PMD needs to be done prior to + * releasing pages. Since pages are still isolated and + * locked here, acquiring anon_vma_lock_write is unnecessary. + */ + pmd_ptl = pmd_lock(vma->vm_mm, pmd); + pmd_populate(vma->vm_mm, pmd, pmd_pgtable(rollback)); + spin_unlock(pmd_ptl); + /* + * Release both raw and compound pages isolated + * in __collapse_huge_page_isolate. + */ + 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))) { + src_page = pte_page(pteval); + if (!PageCompound(src_page)) + release_pte_page(src_page); + } + } + list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) { + list_del(&src_page->lru); + release_pte_page(src_page); } } - list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) { - list_del(&src_page->lru); - mod_node_page_state(page_pgdat(src_page), - NR_ISOLATED_ANON + page_is_file_lru(src_page), - -compound_nr(src_page)); - unlock_page(src_page); - free_swap_cache(src_page); - putback_lru_page(src_page); - } + return copy_succeeded; } static void khugepaged_alloc_sleep(void) @@ -981,6 +1051,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, int result = SCAN_FAIL; struct vm_area_struct *vma; struct mmu_notifier_range range; + bool copied = false; VM_BUG_ON(address & ~HPAGE_PMD_MASK); @@ -1084,9 +1155,13 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, */ anon_vma_unlock_write(vma->anon_vma); - __collapse_huge_page_copy(pte, hpage, vma, address, pte_ptl, - &compound_pagelist); + copied = __collapse_huge_page_copy(pte, hpage, 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 From patchwork Mon Nov 7 02:53:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiaqi Yan X-Patchwork-Id: 13033758 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 16E6AC43217 for ; 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Sun, 06 Nov 2022 18:54:06 -0800 (PST) Date: Sun, 6 Nov 2022 18:53:59 -0800 In-Reply-To: <20221107025359.2911028-1-jiaqiyan@google.com> Mime-Version: 1.0 References: <20221107025359.2911028-1-jiaqiyan@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221107025359.2911028-3-jiaqiyan@google.com> Subject: [PATCH v6 2/2] mm/khugepaged: recover from poisoned file-backed memory From: Jiaqi Yan To: kirill.shutemov@linux.intel.com, kirill@shutemov.name, shy828301@gmail.com, tongtiangen@huawei.com Cc: tony.luck@intel.com, naoya.horiguchi@nec.com, linmiaohe@huawei.com, jiaqiyan@google.com, linux-mm@kvack.org, akpm@linux-foundation.org ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=MOPoVYHG; spf=pass (imf17.hostedemail.com: domain of 3TnNoYwgKCPcihZphxZmfnnfkd.bnlkhmtw-lljuZbj.nqf@flex--jiaqiyan.bounces.google.com designates 209.85.128.202 as permitted sender) smtp.mailfrom=3TnNoYwgKCPcihZphxZmfnnfkd.bnlkhmtw-lljuZbj.nqf@flex--jiaqiyan.bounces.google.com; 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dkim=pass header.d=google.com header.s=20210112 header.b=MOPoVYHG; spf=pass (imf17.hostedemail.com: domain of 3TnNoYwgKCPcihZphxZmfnnfkd.bnlkhmtw-lljuZbj.nqf@flex--jiaqiyan.bounces.google.com designates 209.85.128.202 as permitted sender) smtp.mailfrom=3TnNoYwgKCPcihZphxZmfnnfkd.bnlkhmtw-lljuZbj.nqf@flex--jiaqiyan.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam05 X-Rspam-User: X-HE-Tag: 1667789647-519036 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_file roll back when copying pages failed. More concretely: - extract copying operations into a separate loop - postpone the updates for nr_none until both scanning and copying succeeded - postpone joining small xarray entries until both scanning and copying succeeded - postpone the update operations to NR_XXX_THPS until both scanning and copying succeeded - for non-SHMEM file, roll back filemap_nr_thps_inc if scan succeeded but copying failed Tested manually: 0. Enable khugepaged on system under test. Mount tmpfs at /mnt/ramdisk. 1. Start a two-thread application. Each thread allocates a chunk of non-huge memory buffer from /mnt/ramdisk. 2. Pick 4 random buffer address (2 in each thread) and inject uncorrectable memory errors at physical addresses. 3. Signal both threads to make their memory buffer collapsible, i.e. calling madvise(MADV_HUGEPAGE). 4. Wait and then check kernel log: khugepaged is able to recover from poisoned pages by skipping them. 5. Signal both thread to inspect their buffer contents and make sure no data corruption. Signed-off-by: Jiaqi Yan --- mm/khugepaged.c | 74 ++++++++++++++++++++++++++++++------------------- 1 file changed, 45 insertions(+), 29 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index c1f225327bc05..d54527b77e365 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1776,7 +1776,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, struct collapse_control *cc) { struct address_space *mapping = file->f_mapping; - struct page *hpage; + struct page *hpage, *page, *tmp; pgoff_t index = 0, end = start + HPAGE_PMD_NR; LIST_HEAD(pagelist); XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); @@ -1821,7 +1821,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, xas_set(&xas, start); for (index = start; index < end; index++) { - struct page *page = xas_next(&xas); + page = xas_next(&xas); VM_BUG_ON(index != xas.xa_index); if (is_shmem) { @@ -2003,10 +2003,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, } nr = thp_nr_pages(hpage); - if (is_shmem) - __mod_lruvec_page_state(hpage, NR_SHMEM_THPS, nr); - else { - __mod_lruvec_page_state(hpage, NR_FILE_THPS, nr); + if (!is_shmem) { filemap_nr_thps_inc(mapping); /* * Paired with smp_mb() in do_dentry_open() to ensure @@ -2017,21 +2014,10 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, smp_mb(); if (inode_is_open_for_write(mapping->host)) { result = SCAN_FAIL; - __mod_lruvec_page_state(hpage, NR_FILE_THPS, -nr); filemap_nr_thps_dec(mapping); goto xa_locked; } } - - if (nr_none) { - __mod_lruvec_page_state(hpage, NR_FILE_PAGES, nr_none); - /* nr_none is always 0 for non-shmem. */ - __mod_lruvec_page_state(hpage, NR_SHMEM, nr_none); - } - - /* Join all the small entries into a single multi-index entry */ - xas_set_order(&xas, start, HPAGE_PMD_ORDER); - xas_store(&xas, hpage); xa_locked: xas_unlock_irq(&xas); xa_unlocked: @@ -2044,20 +2030,34 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, try_to_unmap_flush(); if (result == SCAN_SUCCEED) { - struct page *page, *tmp; - /* * Replacing old pages with new one has succeeded, now we - * need to copy the content and free the old pages. + * attempt to copy the contents. */ index = start; - list_for_each_entry_safe(page, tmp, &pagelist, lru) { + list_for_each_entry(page, &pagelist, lru) { while (index < page->index) { clear_highpage(hpage + (index % HPAGE_PMD_NR)); index++; } - copy_highpage(hpage + (page->index % HPAGE_PMD_NR), - page); + if (copy_highpage_mc(hpage + (page->index % HPAGE_PMD_NR), page)) { + result = SCAN_COPY_MC; + break; + } + index++; + } + while (result == SCAN_SUCCEED && index < end) { + clear_highpage(hpage + (page->index % HPAGE_PMD_NR)); + index++; + } + } + + if (result == SCAN_SUCCEED) { + /* + * Copying old pages to huge one has succeeded, now we + * need to free the old pages. + */ + list_for_each_entry_safe(page, tmp, &pagelist, lru) { list_del(&page->lru); page->mapping = NULL; page_ref_unfreeze(page, 1); @@ -2065,12 +2065,23 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, ClearPageUnevictable(page); unlock_page(page); put_page(page); - index++; } - while (index < end) { - clear_highpage(hpage + (index % HPAGE_PMD_NR)); - index++; + + xas_lock_irq(&xas); + if (is_shmem) + __mod_lruvec_page_state(hpage, NR_SHMEM_THPS, nr); + else + __mod_lruvec_page_state(hpage, NR_FILE_THPS, nr); + + if (nr_none) { + __mod_lruvec_page_state(hpage, NR_FILE_PAGES, nr_none); + /* nr_none is always 0 for non-shmem. */ + __mod_lruvec_page_state(hpage, NR_SHMEM, nr_none); } + /* Join all the small entries into a single multi-index entry. */ + xas_set_order(&xas, start, HPAGE_PMD_ORDER); + xas_store(&xas, hpage); + xas_unlock_irq(&xas); SetPageUptodate(hpage); page_ref_add(hpage, HPAGE_PMD_NR - 1); @@ -2086,8 +2097,6 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, unlock_page(hpage); hpage = NULL; } else { - struct page *page; - /* Something went wrong: roll back page cache changes */ xas_lock_irq(&xas); if (nr_none) { @@ -2121,6 +2130,13 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, xas_lock_irq(&xas); } VM_BUG_ON(nr_none); + /* + * Undo the updates of filemap_nr_thps_inc for non-SHMEM file only. + * This undo is not needed unless failure is due to SCAN_COPY_MC. + */ + if (!is_shmem && result == SCAN_COPY_MC) + filemap_nr_thps_dec(mapping); + xas_unlock_irq(&xas); hpage->mapping = NULL;