mm/madvise: free hwpoison and swapin error entry in madvise_free_pte_range

Once the MADV_FREE operation has succeeded, callers can expect they might
get zero-fill pages if accessing the memory again.  Therefore it should be
safe to delete the hwpoison entry and swapin error entry.  There is no
reason to kill the process if it has called MADV_FREE on the range.

Link: https://lkml.kernel.org/r/20220519125030.21486-4-linmiaohe@huawei.comSigned-off-by: NMiaohe Lin <linmiaohe@huawei.com>
Suggested-by: NAlistair Popple <apopple@nvidia.com>
Acked-by: NDavid Hildenbrand <david@redhat.com>
Reviewed-by: NNaoya Horiguchi <naoya.horiguchi@nec.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>

mm/madvise.c

@@ -624,11 +624,14 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 			swp_entry_t entry;
 
 			entry = pte_to_swp_entry(ptent);
-			if (non_swap_entry(entry))
-				continue;
-			nr_swap--;
-			free_swap_and_cache(entry);
-			pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
+			if (!non_swap_entry(entry)) {
+				nr_swap--;
+				free_swap_and_cache(entry);
+				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
+			} else if (is_hwpoison_entry(entry) ||
+				   is_swapin_error_entry(entry)) {
+				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
+			}
 			continue;
 		}