From patchwork Tue Apr 5 20:51:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiaqi Yan X-Patchwork-Id: 12801949 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 4BA6CC433EF for ; Tue, 5 Apr 2022 20:52:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4E2088D0001; Tue, 5 Apr 2022 16:52:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 48F626B0074; Tue, 5 Apr 2022 16:52:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 308F88D0001; Tue, 5 Apr 2022 16:52:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 23DF46B0073 for ; Tue, 5 Apr 2022 16:52:03 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id D80111E44 for ; Tue, 5 Apr 2022 20:51:52 +0000 (UTC) X-FDA: 79324022064.14.42FDD8A Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) by imf14.hostedemail.com (Postfix) with ESMTP id 6D13B10001E for ; Tue, 5 Apr 2022 20:51:52 +0000 (UTC) Received: by mail-yb1-f202.google.com with SMTP id i13-20020a056902068d00b0063da6c20dccso215743ybt.10 for ; Tue, 05 Apr 2022 13:51:52 -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=Uld97CUVDeKpI7YCgqmUQvS0IGT+6Gm86pMoV3kbgxQ=; b=XBD0luPDWXG4ycN80j7LZseHtdzfaPk9rpzXNjn6ZH9Y++ZVHN85FWVlnwAED65P4m GdOSThL9Yf80Q11Jv1Rchy2AeaZ8X2NkF7onu5ZhrQbeT/+lkCMD/e2uQj+NS7Q+fafq 9Ch5Fsil6EJP7De/mb80YLpw6IBrEzMTCiP8T4V0An/XkxZgLSkVrWQtVB1WS0/kkzPW uUKX99Hc6LIi1KdGRRXd9AFU8Uxj4MEoEawN5T6XJ8n0YTXknKAnXP2fQ2VK1bGJD/mp JZfJkKXdb2JexiXw5hHn6RDAqcoGSecrHARyRUjfNpDEb/HT+XJe4g7s4/sm64PT5Lip 1oLQ== 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=Uld97CUVDeKpI7YCgqmUQvS0IGT+6Gm86pMoV3kbgxQ=; b=dX35Yr4p0cvp/tbPv4Js1HVcn5n/QNK+pcGIS3KlUcWmnQ7mzkqwvrEXAYv/vFIKwS XOqUPoLriyYjSNPqh1mefJhKbdAshBMwX2H+UcsPF/+/nJaqoCYdO5s6CYOS6YCLx1Ha kASoU6vB+RvmepaqXU/SlzTXJbf8pvCeDi5VOjGcc/t+N+we6VjO59UenYX4otCqdZLf PH+nF/4IgMb4y98kE9klZ9UDBiyUM3/PLdUzf04HDs0GuCjweUoqYgVQ4QcBlyLKYHPi HyD3Wwruz9tIHCR5IOX8oyg261jeHh4IqrjPEASnpAlDbmjkTlaD19f5wxATUtU1g9g3 2rMA== X-Gm-Message-State: AOAM530AEKOTQ21td4rXiJeM9U56wvqbSkdjz7EndR9qfoujA0oq3nlN 3FZz1G/bvdWNxBu4us+6kY76A1FcWPDLXw== X-Google-Smtp-Source: ABdhPJx4AoJct3z8/SLRlLi73KhPCnWSY33sMmzuQTTOGUOWU7YHxUhNw5C+B131GMA8gL/ly0Z0bsjnYgKuMw== X-Received: from yjqkernel.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1837]) (user=jiaqiyan job=sendgmr) by 2002:a81:8507:0:b0:2eb:9715:78d3 with SMTP id v7-20020a818507000000b002eb971578d3mr4531200ywf.304.1649191911577; Tue, 05 Apr 2022 13:51:51 -0700 (PDT) Date: Tue, 5 Apr 2022 13:51:45 -0700 In-Reply-To: <20220405205146.411595-1-jiaqiyan@google.com> Message-Id: <20220405205146.411595-2-jiaqiyan@google.com> Mime-Version: 1.0 References: <20220405205146.411595-1-jiaqiyan@google.com> X-Mailer: git-send-email 2.35.1.1094.g7c7d902a7c-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, jiaqiyan@google.com, linux-mm@kvack.org X-Stat-Signature: r95es9wmk15g9wp3idqy6pzejpo5ufx6 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 6D13B10001E Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=XBD0luPD; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf14.hostedemail.com: domain of 356tMYggKCIoxwo4wCo1u22uzs.q20zw18B-00y9oqy.25u@flex--jiaqiyan.bounces.google.com designates 209.85.219.202 as permitted sender) smtp.mailfrom=356tMYggKCIoxwo4wCo1u22uzs.q20zw18B-00y9oqy.25u@flex--jiaqiyan.bounces.google.com X-Rspam-User: X-HE-Tag: 1649191912-177115 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 Signed-off-by: Jiaqi Yan --- include/linux/highmem.h | 18 ++++++ mm/khugepaged.c | 138 ++++++++++++++++++++++++++++++---------- 2 files changed, 123 insertions(+), 33 deletions(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 39bb9b47fa9cd..5d4b2af113496 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -296,6 +296,24 @@ static inline void copy_highpage(struct page *to, struct page *from) kunmap_local(vfrom); } +/* + * Machine check exception handled version of copy_highpage. + * Return true if copying page content failed; otherwise false. + */ +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; +} + #endif static inline void memcpy_page(struct page *dst_page, size_t dst_off, diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 131492fd1148b..eecaeaf6eaebe 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 copy succeeds; + * otherwise restore the original pmd page table. Returns true if copy + * 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);