From patchwork Tue May 24 02:53:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiaqi Yan X-Patchwork-Id: 12859632 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 2A1E8C433F5 for ; Tue, 24 May 2022 02:54:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A76986B0075; Mon, 23 May 2022 22:54:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A005F8D0001; Mon, 23 May 2022 22:54:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 84FBA6B007B; Mon, 23 May 2022 22:54:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 69D6C6B0075 for ; Mon, 23 May 2022 22:54:03 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 461EA3546C for ; Tue, 24 May 2022 02:54:03 +0000 (UTC) X-FDA: 79499117166.10.0355D7F Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) by imf16.hostedemail.com (Postfix) with ESMTP id 43ACA180022 for ; Tue, 24 May 2022 02:53:49 +0000 (UTC) Received: by mail-pj1-f73.google.com with SMTP id s1-20020a17090a760100b001dfa6169b1eso599243pjk.0 for ; Mon, 23 May 2022 19:54:02 -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=ZdT2Sfqp0byoGmfTYuvjyYM21Q4H8ycsEtX02VUm7c8=; b=WdDWIDhAHw/oNTM6Y831J4uwVbC05YjPHaXgbWuhEgtY8aGq0Pk2KVuAPitrjtPPu0 +0KQ4w73qd/tjhIzEMTcdSOcnVzAXbpO5bbfofovYUOsSHb0Ke8U31rZYLyFwwvAgfVi AadcLDXBYwB6njfOx8uV96cNjcgKDXEX4/toL8U1TPRayF3SjRlohbRchpCDyNhqSH79 fUoEhrsY+oFGpWS1/E/XJ6IxlM0dlQ7uU0D/NsD9VYx0lTwrcGTSkwVvEMjKOPf8ojy5 rldTUi63pMGshIoGYTCO3417tIkDT9T409M3WiX4wAhKjjUG/WC0pXCXRucR6m+ih/VP EGMw== 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=ZdT2Sfqp0byoGmfTYuvjyYM21Q4H8ycsEtX02VUm7c8=; b=QzXIcu2uNLm5vnGr7c1/ojd6cg8/G55Cd5pclQ38JynHFTts964qYRV0RTymVL9mmu n4tBmAQc7SGZ9rJpYdK1ckCsep7YS1BsvHg2mCpMFIbMBUBYj5rHyCmz8mHVENYaloKw pxr50yfD/mk4kKqg8P6xp7m1oqGaNtwOIxVNKB0BaFY8EzmM1fIw/bhacjZDJgg7V5sZ mPqcs7esOEjmtaHqO11cpc8pgHHmiHIq42ip3YOpQRCXf7WnO6c+mhU9P+hxsGQ/TjEr OAlr5j/oT/kegZ0HbTSuuY2zbnXAEMhCqtCPLbBJZvCdBGT8tVDc8HCjyQDVoTnc4mwy uvAA== X-Gm-Message-State: AOAM532lu2rmcwxhmg69gMRu9UiFQiFiKDtv+MjT9LqiNrjkSRwJkfpy YT3lR22ncVY/Vx4/I1hOTE9bP2LQhur3dQ== X-Google-Smtp-Source: ABdhPJzISv1OyqGBiEcm9tGURrEl771YZ/SCxEoupESeHixq/4p5Zsli916l6i1kU6GLSNwvOrW6Jbla8/MSoQ== X-Received: from yjqkernel.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1837]) (user=jiaqiyan job=sendgmr) by 2002:a17:90b:3a85:b0:1e0:548:2bf7 with SMTP id om5-20020a17090b3a8500b001e005482bf7mr2229164pjb.55.1653360841877; Mon, 23 May 2022 19:54:01 -0700 (PDT) Date: Mon, 23 May 2022 19:53:51 -0700 In-Reply-To: <20220524025352.1381911-1-jiaqiyan@google.com> Message-Id: <20220524025352.1381911-2-jiaqiyan@google.com> Mime-Version: 1.0 References: <20220524025352.1381911-1-jiaqiyan@google.com> X-Mailer: git-send-email 2.36.1.124.g0e6072fb45-goog Subject: [PATCH v3 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, jiaqiyan@google.com, linux-mm@kvack.org X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 43ACA180022 X-Stat-Signature: qhqx6j6rrx7y9imd6dio4zbs5enacnra X-Rspam-User: Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=WdDWIDhA; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf16.hostedemail.com: domain of 3yUiMYggKCKYPOGWOeGTMUUMRK.IUSROTad-SSQbGIQ.UXM@flex--jiaqiyan.bounces.google.com designates 209.85.216.73 as permitted sender) smtp.mailfrom=3yUiMYggKCKYPOGWOeGTMUUMRK.IUSROTad-SSQbGIQ.UXM@flex--jiaqiyan.bounces.google.com X-HE-Tag: 1653360829-83761 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 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 ++++ include/trace/events/huge_memory.h | 27 +++++- mm/khugepaged.c | 146 ++++++++++++++++++++++------- 3 files changed, 158 insertions(+), 34 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/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h index 4fdb14a81108b..7e02c0aa2f728 100644 --- a/include/trace/events/huge_memory.h +++ b/include/trace/events/huge_memory.h @@ -34,7 +34,8 @@ 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 @@ -167,5 +168,29 @@ TRACE_EVENT(mm_collapse_huge_page_swapin, __entry->ret) ); +TRACE_EVENT(mm_collapse_huge_page_copy, + + TP_PROTO(struct page *start, struct page *poisoned, int status), + + TP_ARGS(start, poisoned, status), + + TP_STRUCT__entry( + __field(unsigned long, start_pfn) + __field(unsigned long, poisoned_pfn) + __field(int, status) + ), + + TP_fast_assign( + __entry->start_pfn = start ? page_to_pfn(start) : -1; + __entry->poisoned_pfn = poisoned ? page_to_pfn(poisoned) : -1; + __entry->status = status; + ), + + TP_printk("start_pfn=0x%lx, poisoned_pfn=0x%lx, status=%s", + __entry->start_pfn, + __entry->poisoned_pfn, + __print_symbolic(__entry->status, SCAN_STATUS)) +); + #endif /* __HUGE_MEMORY_H */ #include diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 131492fd1148b..1b08e31ba081a 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 +740,104 @@ 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 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 orginal normal pages' 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; + trace_mm_collapse_huge_page_copy(pte_page(*pte), + src_page, SCAN_COPY_MC); + break; + } + } + } + + if (copy_succeeded) + trace_mm_collapse_huge_page_copy(pte_page(*pte), + NULL, SCAN_SUCCEED); + else { + /* + * Copying failed, 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); + } + + 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 +845,8 @@ 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 +1129,7 @@ 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 +1241,13 @@ 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 +1432,14 @@ 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 +2241,13 @@ 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) still held if scan failed; + * 2) released if scan succeeded. + * It is not affected by collapsing or copying + * operations. + */ ret = khugepaged_scan_pmd(mm, vma, khugepaged_scan.address, hpage);