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 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.
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
v3 resend:
- enhance unuse_pte() if ksm_might_need_to_copy() return -EHWPOISON
- fix issue found by lkp
mm/ksm.c | 8 ++++++--
mm/memory.c | 3 +++
mm/swapfile.c | 20 ++++++++++++++------
3 files changed, 23 insertions(+), 8 deletions(-)
diff --git a/mm/ksm.c b/mm/ksm.c
index dd02780c387f..83e2f74ae7da 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2629,8 +2629,12 @@ 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);
+ new_page = ERR_PTR(-EHWPOISON);
+ memory_failure_queue(page_to_pfn(page), 0);
+ return new_page;
+ }
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..0efb1c2c2415 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 (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
