mm/swapfile: fix wrong swap entry type for hwpoisoned swapcache page

Patch series "A few fixup patches for mm", v2.

This series contains a few fixup patches to fix potential unexpected
return value, fix wrong swap entry type for hwpoisoned swapcache page and
so on.  More details can be found in the respective changelogs.

This patch (of 3):

Hwpoisoned dirty swap cache page is kept in the swap cache and there's
simple interception code in do_swap_page() to catch it.  But when trying
to swapoff, unuse_pte() will wrongly install a general sense of "future
accesses are invalid" swap entry for hwpoisoned swap cache page due to
unaware of such type of page.  The user will receive SIGBUS signal without
expected BUS_MCEERR_AR payload.  BTW, typo 'hwposioned' is fixed.

Link: https://lkml.kernel.org/r/20230727115643.639741-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20230727115643.639741-2-linmiaohe@huawei.com
Fixes: 6b970599e807 ("mm: hwpoison: support recovery from ksm_might_need_to_copy()")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/ksm.c b/mm/ksm.c
index ba266359da55f1f0f8cfa82fccffad5fbd5d5de3..d20d7662419beadd6133cb1df445f9e41a03287b 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2784,6 +2784,8 @@ struct page *ksm_might_need_to_copy(struct page *page,
                        anon_vma->root == vma->anon_vma->root) {
                return page;            /* still no need to copy it */
        }
+       if (PageHWPoison(page))
+               return ERR_PTR(-EHWPOISON);
        if (!PageUptodate(page))
                return page;            /* let do_swap_page report the error */
 

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 8e6dde68b38904a97f6b30fbda4ffbe1122c7837..b15112b1f1a8bceea5872b5e333b4fcac76b2901 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1746,7 +1746,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
        struct page *swapcache;
        spinlock_t *ptl;
        pte_t *pte, new_pte, old_pte;
-       bool hwposioned = false;
+       bool hwpoisoned = PageHWPoison(page);
        int ret = 1;
 
        swapcache = page;
@@ -1754,7 +1754,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
        if (unlikely(!page))
                return -ENOMEM;
        else if (unlikely(PTR_ERR(page) == -EHWPOISON))
-               hwposioned = true;
+               hwpoisoned = true;
 
        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
        if (unlikely(!pte || !pte_same_as_swp(ptep_get(pte),
@@ -1765,11 +1765,11 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 
        old_pte = ptep_get(pte);
 
-       if (unlikely(hwposioned || !PageUptodate(page))) {
+       if (unlikely(hwpoisoned || !PageUptodate(page))) {
                swp_entry_t swp_entry;
 
                dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
-               if (hwposioned) {
+               if (hwpoisoned) {
                        swp_entry = make_hwpoison_entry(swapcache);
                        page = swapcache;
                } else {