The quilt patch titled
Subject: mm: hwpoison: support recovery from ksm_might_need_to_copy()
has been removed from the -mm tree. Its filename was
mm-hwposion-support-recovery-from-ksm_might_need_to_copy.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Subject: mm: hwpoison: support recovery from ksm_might_need_to_copy()
Date: Fri, 9 Dec 2022 15:28:01 +0800
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@xxxxxxxxxx: enhance unuse_pte(), fix issue found by lkp]
Link: https://lkml.kernel.org/r/20221213120523.141588-1-wangkefeng.wang@xxxxxxxxxx
[wangkefeng.wang@xxxxxxxxxx: update changelog, alter ksm_might_need_to_copy(), restore unlikely() in unuse_pte()]
Link: https://lkml.kernel.org/r/20230201074433.96641-1-wangkefeng.wang@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20221209072801.193221-1-wangkefeng.wang@xxxxxxxxxx
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 7 +++++--
mm/memory.c | 3 +++
mm/swapfile.c | 20 ++++++++++++++------
3 files changed, 22 insertions(+), 8 deletions(-)
--- a/mm/ksm.c~mm-hwposion-support-recovery-from-ksm_might_need_to_copy
+++ a/mm/ksm.c
@@ -2629,8 +2629,11 @@ struct page *ksm_might_need_to_copy(stru
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);
--- a/mm/memory.c~mm-hwposion-support-recovery-from-ksm_might_need_to_copy
+++ a/mm/memory.c
@@ -3840,6 +3840,9 @@ vm_fault_t do_swap_page(struct vm_fault
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);
--- a/mm/swapfile.c~mm-hwposion-support-recovery-from-ksm_might_need_to_copy
+++ a/mm/swapfile.c
@@ -1764,12 +1764,15 @@ static int unuse_pte(struct vm_area_stru
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_stru
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_stru
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:
_
Patches currently in -mm which might be from wangkefeng.wang@xxxxxxxxxx are
