| Message ID | 20230201074433.96641-1-wangkefeng.wang@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v4] mm: hwposion: support recovery from ksm_might_need_to_copy() | expand |
On Wed, 1 Feb 2023 15:44:33 +0800 Kefeng Wang <wangkefeng.wang@huawei.com> wrote: > When the kernel copy 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. > Some review input would be helpful. Are we able to identify a Fixes: target for this? I assume that a -stable backport is desirable? Thanks. > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -2629,8 +2629,11 @@ struct page *ksm_might_need_to_copy(struct page *page, > new_page = NULL; > } > if (new_page) { > - copy_user_highpage(new_page, page, address, vma); > - > + if (copy_mc_user_highpage(new_page, page, address, vma)) { > + put_page(new_page); > + memory_failure_queue(page_to_pfn(page), 0); > + return ERR_PTR(-EHWPOISON); > + } > SetPageDirty(new_page); > __SetPageUptodate(new_page); > __SetPageLocked(new_page); > diff --git a/mm/memory.c b/mm/memory.c > index aad226daf41b..5b2c137dfb2a 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3840,6 +3840,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > if (unlikely(!page)) { > ret = VM_FAULT_OOM; > goto out_page; > + } else if (unlikely(PTR_ERR(page) == -EHWPOISON)) { > + ret = VM_FAULT_HWPOISON; > + goto out_page; > } > folio = page_folio(page); > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 908a529bca12..3ef2468d7130 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1763,12 +1763,15 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, > struct page *swapcache; > spinlock_t *ptl; > pte_t *pte, new_pte; > + bool hwposioned = false; > int ret = 1; > > swapcache = page; > page = ksm_might_need_to_copy(page, vma, addr); > if (unlikely(!page)) > return -ENOMEM; > + else if (unlikely(PTR_ERR(page) == -EHWPOISON)) > + hwposioned = true; > > pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); > if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) { > @@ -1776,15 +1779,19 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, > goto out; > } > > - if (unlikely(!PageUptodate(page))) { > - pte_t pteval; > + if (unlikely(hwposioned || !PageUptodate(page))) { > + swp_entry_t swp_entry; > > dec_mm_counter(vma->vm_mm, MM_SWAPENTS); > - pteval = swp_entry_to_pte(make_swapin_error_entry()); > - set_pte_at(vma->vm_mm, addr, pte, pteval); > - swap_free(entry); > + if (hwposioned) { > + swp_entry = make_hwpoison_entry(swapcache); > + page = swapcache; > + } else { > + swp_entry = make_swapin_error_entry(); > + } > + new_pte = swp_entry_to_pte(swp_entry); > ret = 0; > - goto out; > + goto setpte; > } > > /* See do_swap_page() */ > @@ -1816,6 +1823,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, > new_pte = pte_mksoft_dirty(new_pte); > if (pte_swp_uffd_wp(*pte)) > new_pte = pte_mkuffd_wp(new_pte); > +setpte: > set_pte_at(vma->vm_mm, addr, pte, new_pte); > swap_free(entry); > out: > -- > 2.35.3 >
On Wed, Feb 01, 2023 at 03:44:33PM +0800, Kefeng Wang wrote: > When the kernel copy 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. > > Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Looks good to me, thank you. Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
diff --git a/mm/ksm.c b/mm/ksm.c index dd02780c387f..addf490da146 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2629,8 +2629,11 @@ struct page *ksm_might_need_to_copy(struct page *page, new_page = NULL; } if (new_page) { - copy_user_highpage(new_page, page, address, vma); - + if (copy_mc_user_highpage(new_page, page, address, vma)) { + put_page(new_page); + memory_failure_queue(page_to_pfn(page), 0); + return ERR_PTR(-EHWPOISON); + } SetPageDirty(new_page); __SetPageUptodate(new_page); __SetPageLocked(new_page); diff --git a/mm/memory.c b/mm/memory.c index aad226daf41b..5b2c137dfb2a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3840,6 +3840,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) if (unlikely(!page)) { ret = VM_FAULT_OOM; goto out_page; + } else if (unlikely(PTR_ERR(page) == -EHWPOISON)) { + ret = VM_FAULT_HWPOISON; + goto out_page; } folio = page_folio(page); diff --git a/mm/swapfile.c b/mm/swapfile.c index 908a529bca12..3ef2468d7130 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1763,12 +1763,15 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, struct page *swapcache; spinlock_t *ptl; pte_t *pte, new_pte; + bool hwposioned = false; int ret = 1; swapcache = page; page = ksm_might_need_to_copy(page, vma, addr); if (unlikely(!page)) return -ENOMEM; + else if (unlikely(PTR_ERR(page) == -EHWPOISON)) + hwposioned = true; pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) { @@ -1776,15 +1779,19 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, goto out; } - if (unlikely(!PageUptodate(page))) { - pte_t pteval; + if (unlikely(hwposioned || !PageUptodate(page))) { + swp_entry_t swp_entry; dec_mm_counter(vma->vm_mm, MM_SWAPENTS); - pteval = swp_entry_to_pte(make_swapin_error_entry()); - set_pte_at(vma->vm_mm, addr, pte, pteval); - swap_free(entry); + if (hwposioned) { + swp_entry = make_hwpoison_entry(swapcache); + page = swapcache; + } else { + swp_entry = make_swapin_error_entry(); + } + new_pte = swp_entry_to_pte(swp_entry); ret = 0; - goto out; + goto setpte; } /* See do_swap_page() */ @@ -1816,6 +1823,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, new_pte = pte_mksoft_dirty(new_pte); if (pte_swp_uffd_wp(*pte)) new_pte = pte_mkuffd_wp(new_pte); +setpte: set_pte_at(vma->vm_mm, addr, pte, new_pte); swap_free(entry); out:
When the kernel copy 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. Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> --- v4: - update changelog and directly return ERR_PTR(-EHWPOISON) in ksm_might_need_to_copy() suggested HORIGUCHI NAOYA - add back unlikely in unuse_pte() mm/ksm.c | 7 +++++-- mm/memory.c | 3 +++ mm/swapfile.c | 20 ++++++++++++++------ 3 files changed, 22 insertions(+), 8 deletions(-)