[PATCH 1/3] mm/memory-failure: Pass the folio and the page to collect_procs()

["Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>]

Both collect_procs_anon() and collect_procs_file() iterate over the VMA
interval trees looking for a single pgoff, so it is wrong to look for
the pgoff of the head page as is currently done.  However, it is also
wrong to look at page->mapping of the precise page as this is invalid
for tail pages.  Clear up the confusion by passing both the folio and
the precise page to collect_procs().

Fixes: 415c64c1453a ("mm/memory-failure: split thp earlier in memory error handling")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 mm/memory-failure.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 660c21859118..6953bda11e6e 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -595,10 +595,9 @@ struct task_struct *task_early_kill(struct task_struct *tsk, int force_early)
 /*
  * Collect processes when the error hit an anonymous page.
  */
-static void collect_procs_anon(struct page *page, struct list_head *to_kill,
-				int force_early)
+static void collect_procs_anon(struct folio *folio, struct page *page,
+		struct list_head *to_kill, int force_early)
 {
-	struct folio *folio = page_folio(page);
 	struct vm_area_struct *vma;
 	struct task_struct *tsk;
 	struct anon_vma *av;
@@ -633,12 +632,12 @@ static void collect_procs_anon(struct page *page, struct list_head *to_kill,
 /*
  * Collect processes when the error hit a file mapped page.
  */
-static void collect_procs_file(struct page *page, struct list_head *to_kill,
-				int force_early)
+static void collect_procs_file(struct folio *folio, struct page *page,
+		struct list_head *to_kill, int force_early)
 {
 	struct vm_area_struct *vma;
 	struct task_struct *tsk;
-	struct address_space *mapping = page->mapping;
+	struct address_space *mapping = folio->mapping;
 	pgoff_t pgoff;
 
 	i_mmap_lock_read(mapping);
@@ -704,17 +703,17 @@ static void collect_procs_fsdax(struct page *page,
 /*
  * Collect the processes who have the corrupted page mapped to kill.
  */
-static void collect_procs(struct page *page, struct list_head *tokill,
-				int force_early)
+static void collect_procs(struct folio *folio, struct page *page,
+		struct list_head *tokill, int force_early)
 {
-	if (!page->mapping)
+	if (!folio->mapping)
 		return;
 	if (unlikely(PageKsm(page)))
 		collect_procs_ksm(page, tokill, force_early);
 	else if (PageAnon(page))
-		collect_procs_anon(page, tokill, force_early);
+		collect_procs_anon(folio, page, tokill, force_early);
 	else
-		collect_procs_file(page, tokill, force_early);
+		collect_procs_file(folio, page, tokill, force_early);
 }
 
 struct hwpoison_walk {
@@ -1602,7 +1601,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	 * mapped in dirty form.  This has to be done before try_to_unmap,
 	 * because ttu takes the rmap data structures down.
 	 */
-	collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);
+	collect_procs(folio, p, &tokill, flags & MF_ACTION_REQUIRED);
 
 	if (PageHuge(hpage) && !PageAnon(hpage)) {
 		/*
@@ -1772,7 +1771,7 @@ 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(&folio->page, &to_kill, true);
+	collect_procs(folio, &folio->page, &to_kill, true);
 
 	unmap_and_kill(&to_kill, pfn, folio->mapping, folio->index, flags);
 unlock:
-- 
2.42.0