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Mon, 20 Mar 2023 07:42:24 -0700 (PDT) MIME-Version: 1.0 References: <20230305065112.1932255-1-jiaqiyan@google.com> <20230305065112.1932255-2-jiaqiyan@google.com> In-Reply-To: <20230305065112.1932255-2-jiaqiyan@google.com> From: Jiaqi Yan Date: Mon, 20 Mar 2023 07:42:13 -0700 Message-ID: Subject: Re: [PATCH v10 1/3] mm/khugepaged: recover from poisoned anonymous memory To: kirill.shutemov@linux.intel.com, kirill@shutemov.name, shy828301@gmail.com, tongtiangen@huawei.com, tony.luck@intel.com Cc: naoya.horiguchi@nec.com, linmiaohe@huawei.com, linux-mm@kvack.org, osalvador@suse.de, wangkefeng.wang@huawei.com, akpm@linux-foundation.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 551B116000A X-Rspam-User: X-Stat-Signature: m3r6iyfubabxkouq3bpuw3xau8thsyh9 X-HE-Tag: 1679323345-814894 X-HE-Meta: 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 oNBj00tO Ruedeto5aWNV17H2tCtpjCBFVf7KEAZ0dQuVaWZeuVVwS3oYKhlnWAzr+54tAZcXgxAtoKAdrSiMCQgGymtZp0vsAxBD7a13qUTrTITWyNaPoZNhg0aamcjukEQdUbGpUwDkTC3J3SjCqCbXM3ovPwUHdRaxnu6DbHQstJWRVuo0oNImPxz285GBRx7mZzyyMik2BZEs64f5QaIbfnXHHE9za7b7S7oNQs3RBChJTGdejiR1mKKhEZEN6X1RcD1zTrv9BKYcc/OFkb5iay7DV6wO1fJ2WQJy3YvpOX6a7tDrKiB2hN/JYIll50A== 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: ping for review :) On Sat, Mar 4, 2023 at 10:51=E2=80=AFPM Jiaqi Yan wro= te: > > 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/trace/events/huge_memory.h | 3 +- > mm/khugepaged.c | 148 ++++++++++++++++++++++++----- > 2 files changed, 128 insertions(+), 23 deletions(-) > > diff --git a/include/trace/events/huge_memory.h b/include/trace/events/hu= ge_memory.h > index 3e6fb05852f9a..46cce509957ba 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 27956d4404134..c3c217f6ebc6e 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -19,6 +19,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -55,6 +56,7 @@ enum scan_result { > SCAN_CGROUP_CHARGE_FAIL, > SCAN_TRUNCATED, > SCAN_PAGE_HAS_PRIVATE, > + SCAN_COPY_MC, > }; > > #define CREATE_TRACE_POINTS > @@ -681,47 +683,47 @@ static int __collapse_huge_page_isolate(struct vm_a= rea_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= ) > +static void __collapse_huge_page_copy_succeeded(pte_t *pte, > + pmd_t *pmd, > + struct vm_area_struct *vm= a, > + unsigned long address, > + spinlock_t *pte_ptl, > + struct list_head *compoun= d_pagelist) > { > struct page *src_page, *tmp; > pte_t *_pte; > - for (_pte =3D pte; _pte < pte + HPAGE_PMD_NR; > - _pte++, page++, address +=3D PAGE_SIZE) { > - pte_t pteval =3D *_pte; > + pte_t pteval; > + unsigned long _address; > > + for (_pte =3D pte, _address =3D address; _pte < pte + HPAGE_PMD_N= R; > + _pte++, _address +=3D PAGE_SIZE) { > + pteval =3D *_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. > + * pte_ptl mostly unnecessary. > */ > - spin_lock(ptl); > - ptep_clear(vma->vm_mm, address, _pte); > - spin_unlock(ptl); > + spin_lock(pte_ptl); > + pte_clear(vma->vm_mm, _address, _pte); > + spin_unlock(pte_ptl); > } > } else { > src_page =3D 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 > + * 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_lock(pte_ptl); > + ptep_clear(vma->vm_mm, _address, _pte); > page_remove_rmap(src_page, vma, false); > - spin_unlock(ptl); > + spin_unlock(pte_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), > @@ -733,6 +735,104 @@ static void __collapse_huge_page_copy(pte_t *pte, s= truct page *page, > } > } > > +static void __collapse_huge_page_copy_failed(pte_t *pte, > + pmd_t *pmd, > + pmd_t orig_pmd, > + struct vm_area_struct *vma, > + unsigned long address, > + struct list_head *compound_p= agelist) > +{ > + struct page *src_page, *tmp; > + pte_t *_pte; > + pte_t pteval; > + unsigned long _address; > + spinlock_t *pmd_ptl; > + > + /* > + * Re-establish the PMD to point to the original page table > + * entry. 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 =3D pmd_lock(vma->vm_mm, pmd); > + pmd_populate(vma->vm_mm, pmd, pmd_pgtable(orig_pmd)); > + spin_unlock(pmd_ptl); > + /* > + * Release both raw and compound pages isolated > + * in __collapse_huge_page_isolate. > + */ > + for (_pte =3D pte, _address =3D address; _pte < pte + HPAGE_PMD_N= R; > + _pte++, _address +=3D PAGE_SIZE) { > + pteval =3D *_pte; > + if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) > + continue; > + src_page =3D 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); > + } > +} > + > +/* > + * __collapse_huge_page_copy - attempts to copy memory contents from raw > + * pages to a hugepage. Cleans up the raw pages if copying succeeds; > + * otherwise restores the original page table and releases isolated raw = pages. > + * Returns SCAN_SUCCEED if copying succeeds, otherwise returns SCAN_COPY= _MC. > + * > + * @pte: starting of the PTEs to copy from > + * @page: the new hugepage to copy contents to > + * @pmd: pointer to the new hugepage's PMD > + * @orig_pmd: the original raw pages' PMD > + * @vma: the original raw pages' virtual memory area > + * @address: starting address to copy > + * @pte_ptl: lock on raw pages' PTEs > + * @compound_pagelist: list that stores compound pages > + */ > +static int __collapse_huge_page_copy(pte_t *pte, > + struct page *page, > + pmd_t *pmd, > + pmd_t orig_pmd, > + struct vm_area_struct *vma, > + unsigned long address, > + spinlock_t *pte_ptl, > + struct list_head *compound_pagelist) > +{ > + struct page *src_page; > + pte_t *_pte; > + pte_t pteval; > + unsigned long _address; > + int result =3D SCAN_SUCCEED; > + > + /* > + * Copying pages' contents is subject to memory poison at any ite= ration. > + */ > + for (_pte =3D pte, _address =3D address; _pte < pte + HPAGE_PMD_N= R; > + _pte++, page++, _address +=3D PAGE_SIZE) { > + pteval =3D *_pte; > + if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { > + clear_user_highpage(page, _address); > + continue; > + } > + src_page =3D pte_page(pteval); > + if (copy_mc_user_highpage(page, src_page, _address, vma) = > 0) { > + result =3D SCAN_COPY_MC; > + break; > + } > + } > + > + if (likely(result =3D=3D SCAN_SUCCEED)) > + __collapse_huge_page_copy_succeeded(pte, pmd, vma, addres= s, > + pte_ptl, compound_pag= elist); > + else > + __collapse_huge_page_copy_failed(pte, pmd, orig_pmd, vma, > + address, compound_pageli= st); > + > + return result; > +} > + > static void khugepaged_alloc_sleep(void) > { > DEFINE_WAIT(wait); > @@ -1106,9 +1206,13 @@ 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); > + result =3D __collapse_huge_page_copy(pte, hpage, pmd, _pmd, > + vma, address, pte_ptl, > + &compound_pagelist); > pte_unmap(pte); > + if (unlikely(result !=3D SCAN_SUCCEED)) > + goto out_up_write; > + > /* > * spin_lock() below is not the equivalent of smp_wmb(), but > * the smp_wmb() inside __SetPageUptodate() can be reused to > -- > 2.40.0.rc0.216.gc4246ad0f0-goog >