Re: [PATCH RESEND v6 3/9] mm: factor helpers for memory_failure_dev_pagemap

On Thu, Aug 5, 2021 at 6:01 PM Jane Chu [off-list ref] wrote:

On 7/30/2021 3:01 AM, Shiyang Ruan wrote:

quoted

-     /*
-      * Prevent the inode from being freed while we are interrogating
-      * the address_space, typically this would be handled by
-      * lock_page(), but dax pages do not use the page lock. This
-      * also prevents changes to the mapping of this pfn until
-      * poison signaling is complete.
-      */
-     cookie = dax_lock_page(page);
-     if (!cookie)
-             goto out;
-
      if (hwpoison_filter(page)) {
              rc = 0;
-             goto unlock;
+             goto out;
      }

why isn't dax_lock_page() needed for hwpoison_filter() check?

Good catch. hwpoison_filter() is indeed consulting page->mapping->host
which needs to be synchronized against inode lifetime.