mm/memory-failure: check the mapcount of the precise page

commit c79c5a0a00a9457718056b588f312baadf44e471 upstream.

A process may map only some of the pages in a folio, and might be missed
if it maps the poisoned page but not the head page.  Or it might be
unnecessarily hit if it maps the head page, but not the poisoned page.

Link: https://lkml.kernel.org/r/20231218135837.3310403-3-willy@infradead.org
Fixes: 7af446a841a2 ("HWPOISON, hugetlb: enable error handling path for hugepage")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index f2397a8..16e002e 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1571,7 +1571,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
         * This check implies we don't kill processes if their pages
         * are in the swap cache early. Those are always late kills.
         */
-       if (!page_mapped(hpage))
+       if (!page_mapped(p))
                return true;
 
        if (PageSwapCache(p)) {
@@ -1622,10 +1622,10 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
                try_to_unmap(folio, ttu);
        }
 
-       unmap_success = !page_mapped(hpage);
+       unmap_success = !page_mapped(p);
        if (!unmap_success)
                pr_err("%#lx: failed to unmap page (mapcount=%d)\n",
-                      pfn, page_mapcount(hpage));
+                      pfn, page_mapcount(p));
 
        /*
         * try_to_unmap() might put mlocked page in lru cache, so call