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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>
This commit is contained in:
Kefeng Wang 2022-12-09 15:28:01 +08:00 committed by Andrew Morton
parent 55d77bae73
commit 6b970599e8
3 changed files with 22 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
mm/ksm.c
View File

@ -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);

3
mm/memory.c
View File

@ -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);

20
mm/swapfile.c
View File

@ -1764,12 +1764,15 @@ 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)))) {
@ -1777,15 +1780,19 @@ 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() */
@ -1817,6 +1824,7 @@ 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: