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mm: hwpoison: support recovery from ksm_might_need_to_copy()
When the kernel copies a page from ksm_might_need_to_copy(), but runs into an uncorrectable error, it will crash since poisoned page is consumed by kernel, this is similar to the issue recently fixed by Copy-on-write poison recovery. When an error is detected during the page copy, return VM_FAULT_HWPOISON in do_swap_page(), and install a hwpoison entry in unuse_pte() when swapoff, which help us to avoid system crash. Note, memory failure on a KSM page will be skipped, but still call memory_failure_queue() to be consistent with general memory failure process, and we could support KSM page recovery in the feature. [wangkefeng.wang@huawei.com: enhance unuse_pte(), fix issue found by lkp] Link: https://lkml.kernel.org/r/20221213120523.141588-1-wangkefeng.wang@huawei.com [wangkefeng.wang@huawei.com: update changelog, alter ksm_might_need_to_copy(), restore unlikely() in unuse_pte()] Link: https://lkml.kernel.org/r/20230201074433.96641-1-wangkefeng.wang@huawei.com Link: https://lkml.kernel.org/r/20221209072801.193221-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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parent
55d77bae73
commit
6b970599e8
7
mm/ksm.c
7
mm/ksm.c
@ -2629,8 +2629,11 @@ struct page *ksm_might_need_to_copy(struct page *page,
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new_page = NULL;
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}
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if (new_page) {
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copy_user_highpage(new_page, page, address, vma);
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if (copy_mc_user_highpage(new_page, page, address, vma)) {
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put_page(new_page);
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memory_failure_queue(page_to_pfn(page), 0);
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return ERR_PTR(-EHWPOISON);
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}
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SetPageDirty(new_page);
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__SetPageUptodate(new_page);
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__SetPageLocked(new_page);
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@ -3840,6 +3840,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
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if (unlikely(!page)) {
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ret = VM_FAULT_OOM;
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goto out_page;
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} else if (unlikely(PTR_ERR(page) == -EHWPOISON)) {
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ret = VM_FAULT_HWPOISON;
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goto out_page;
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}
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folio = page_folio(page);
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@ -1764,12 +1764,15 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
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struct page *swapcache;
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spinlock_t *ptl;
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pte_t *pte, new_pte;
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bool hwposioned = false;
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int ret = 1;
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swapcache = page;
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page = ksm_might_need_to_copy(page, vma, addr);
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if (unlikely(!page))
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return -ENOMEM;
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else if (unlikely(PTR_ERR(page) == -EHWPOISON))
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hwposioned = true;
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pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
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if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) {
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@ -1777,15 +1780,19 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
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goto out;
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}
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if (unlikely(!PageUptodate(page))) {
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pte_t pteval;
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if (unlikely(hwposioned || !PageUptodate(page))) {
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swp_entry_t swp_entry;
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dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
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pteval = swp_entry_to_pte(make_swapin_error_entry());
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set_pte_at(vma->vm_mm, addr, pte, pteval);
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swap_free(entry);
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if (hwposioned) {
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swp_entry = make_hwpoison_entry(swapcache);
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page = swapcache;
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} else {
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swp_entry = make_swapin_error_entry();
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}
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new_pte = swp_entry_to_pte(swp_entry);
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ret = 0;
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goto out;
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goto setpte;
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}
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/* See do_swap_page() */
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@ -1817,6 +1824,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
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new_pte = pte_mksoft_dirty(new_pte);
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if (pte_swp_uffd_wp(*pte))
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new_pte = pte_mkuffd_wp(new_pte);
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setpte:
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set_pte_at(vma->vm_mm, addr, pte, new_pte);
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swap_free(entry);
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out:
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