The patch titled
Subject: mm: hwpoison: support recovery from ksm_might_need_to_copy()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-hwposion-support-recovery-from-ksm_might_need_to_copy.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hwposion-support-recovery-from-ksm_might_need_to_copy.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
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 in ksm_might_need_to_copy(), but runs into
an uncorrectable error, it will crash since the 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,
which helps us to avoid the 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 processes.
Link: https://lkml.kernel.org/r/20221209072801.193221-1-wangkefeng.wang@xxxxxxxxxx
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 8 ++++++--
mm/memory.c | 3 +++
mm/swapfile.c | 2 +-
3 files changed, 10 insertions(+), 3 deletions(-)
--- a/mm/ksm.c~mm-hwposion-support-recovery-from-ksm_might_need_to_copy
+++ a/mm/ksm.c
@@ -2602,8 +2602,12 @@ 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);
+ 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);
--- a/mm/memory.c~mm-hwposion-support-recovery-from-ksm_might_need_to_copy
+++ a/mm/memory.c
@@ -3878,6 +3878,9 @@ 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
@@ -1768,7 +1768,7 @@ static int unuse_pte(struct vm_area_stru
swapcache = page;
page = ksm_might_need_to_copy(page, vma, addr);
- if (unlikely(!page))
+ if (IS_ERR_OR_NULL(page))
return -ENOMEM;
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
_
Patches currently in -mm which might be from wangkefeng.wang@xxxxxxxxxx are
mm-hwposion-support-recovery-from-ksm_might_need_to_copy.patch
mm-add-cond_resched-in-swapin_walk_pmd_entry.patch
