mm: convert DAX lock/unlock page to lock/unlock folio

[ Upstream commit 91e79d22be75fec88ae58d274a7c9e49d6215099 ]

The one caller of DAX lock/unlock page already calls compound_head(), so
use page_folio() instead, then use a folio throughout the DAX code to
remove uses of page->mapping and page->index.

[jane.chu@oracle.com: add comment to mf_generic_kill_procss(), simplify mf_generic_kill_procs:folio initialization]
  Link: https://lkml.kernel.org/r/20230908222336.186313-1-jane.chu@oracle.com
Link: https://lkml.kernel.org/r/20230822231314.349200-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jane Chu <jane.chu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 376907f3a0b3 ("mm/memory-failure: pass the folio and the page to collect_procs()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 16 insertions, 13 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 16e002e08cf8..75eb1d6857e4 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1713,32 +1713,35 @@ static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
 	kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags);
 }
 
+/*
+ * Only dev_pagemap pages get here, such as fsdax when the filesystem
+ * either do not claim or fails to claim a hwpoison event, or devdax.
+ * The fsdax pages are initialized per base page, and the devdax pages
+ * could be initialized either as base pages, or as compound pages with
+ * vmemmap optimization enabled. Devdax is simplistic in its dealing with
+ * hwpoison, such that, if a subpage of a compound page is poisoned,
+ * simply mark the compound head page is by far sufficient.
+ */
 static int mf_generic_kill_procs(unsigned long long pfn, int flags,
 		struct dev_pagemap *pgmap)
 {
-	struct page *page = pfn_to_page(pfn);
+	struct folio *folio = pfn_folio(pfn);
 	LIST_HEAD(to_kill);
 	dax_entry_t cookie;
 	int rc = 0;
 
 	/*
-	 * Pages instantiated by device-dax (not filesystem-dax)
-	 * may be compound pages.
-	 */
-	page = compound_head(page);
-
-	/*
 	 * 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);
+	cookie = dax_lock_folio(folio);
 	if (!cookie)
 		return -EBUSY;
 
-	if (hwpoison_filter(page)) {
+	if (hwpoison_filter(&folio->page)) {
 		rc = -EOPNOTSUPP;
 		goto unlock;
 	}
@@ -1760,7 +1763,7 @@ static int mf_generic_kill_procs(unsigned long long pfn, int flags,
 	 * Use this flag as an indication that the dax page has been
 	 * remapped UC to prevent speculative consumption of poison.
 	 */
-	SetPageHWPoison(page);
+	SetPageHWPoison(&folio->page);
 
 	/*
 	 * Unlike System-RAM there is no possibility to swap in a
@@ -1769,11 +1772,11 @@ static int mf_generic_kill_procs(unsigned long long pfn, int flags,
 	 * SIGBUS (i.e. MF_MUST_KILL)
 	 */
 	flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
-	collect_procs(page, &to_kill, true);
+	collect_procs(&folio->page, &to_kill, true);
 
-	unmap_and_kill(&to_kill, pfn, page->mapping, page->index, flags);
+	unmap_and_kill(&to_kill, pfn, folio->mapping, folio->index, flags);
 unlock:
-	dax_unlock_page(page, cookie);
+	dax_unlock_folio(folio, cookie);
 	return rc;
 }