[PATCH 30/30] mm: Remove PG_error

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

The PG_error bit is now unused; delete it and free up a bit in
page->flags.

Cc: linux-mm@xxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 fs/proc/page.c                         | 1 -
 include/linux/page-flags.h             | 6 +-----
 include/trace/events/mmflags.h         | 1 -
 include/uapi/linux/kernel-page-flags.h | 2 +-
 mm/migrate.c                           | 2 --
 5 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/fs/proc/page.c b/fs/proc/page.c
index 2fb64bdb64eb..05eb6617668a 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -186,7 +186,6 @@ u64 stable_page_flags(const struct page *page)
 #endif
 
 	u |= kpf_copy_bit(k, KPF_LOCKED,	PG_locked);
-	u |= kpf_copy_bit(k, KPF_ERROR,		PG_error);
 	u |= kpf_copy_bit(k, KPF_DIRTY,		PG_dirty);
 	u |= kpf_copy_bit(k, KPF_UPTODATE,	PG_uptodate);
 	u |= kpf_copy_bit(k, KPF_WRITEBACK,	PG_writeback);
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index a9a6e0f7367e..931820c8ea95 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -71,8 +71,6 @@
  * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
  * file-backed pagecache (see mm/vmscan.c).
  *
- * PG_error is set to indicate that an I/O error occurred on this page.
- *
  * PG_arch_1 is an architecture specific page state bit.  The generic code
  * guarantees that this bit is cleared for a page when it first is entered into
  * the page cache.
@@ -108,7 +106,6 @@ enum pageflags {
 	PG_waiters,		/* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
 	PG_active,
 	PG_workingset,
-	PG_error,
 	PG_owner_priv_1,	/* Owner use. If pagecache, fs may use*/
 	PG_arch_1,
 	PG_reserved,
@@ -188,7 +185,7 @@ enum pageflags {
 	 */
 
 	/* At least one page in this folio has the hwpoison flag set */
-	PG_has_hwpoisoned = PG_error,
+	PG_has_hwpoisoned = PG_active,
 	PG_large_rmappable = PG_workingset, /* anon or file-backed */
 };
 
@@ -511,7 +508,6 @@ static inline int TestClearPage##uname(struct page *page) { return 0; }
 
 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
 FOLIO_FLAG(waiters, FOLIO_HEAD_PAGE)
-PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
 PAGEFLAG(Referenced, referenced, PF_HEAD)
 	TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
 	__SETPAGEFLAG(Referenced, referenced, PF_HEAD)
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index e46d6e82765e..4f2a18a11970 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -100,7 +100,6 @@
 #define __def_pageflag_names						\
 	DEF_PAGEFLAG_NAME(locked),					\
 	DEF_PAGEFLAG_NAME(waiters),					\
-	DEF_PAGEFLAG_NAME(error),					\
 	DEF_PAGEFLAG_NAME(referenced),					\
 	DEF_PAGEFLAG_NAME(uptodate),					\
 	DEF_PAGEFLAG_NAME(dirty),					\
diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h
index 6f2f2720f3ac..ff8032227876 100644
--- a/include/uapi/linux/kernel-page-flags.h
+++ b/include/uapi/linux/kernel-page-flags.h
@@ -7,7 +7,7 @@
  */
 
 #define KPF_LOCKED		0
-#define KPF_ERROR		1
+#define KPF_ERROR		1	/* Now unused */
 #define KPF_REFERENCED		2
 #define KPF_UPTODATE		3
 #define KPF_DIRTY		4
diff --git a/mm/migrate.c b/mm/migrate.c
index 2594a00279f1..c0acb52ac4e4 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -561,8 +561,6 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
 {
 	int cpupid;
 
-	if (folio_test_error(folio))
-		folio_set_error(newfolio);
 	if (folio_test_referenced(folio))
 		folio_set_referenced(newfolio);
 	if (folio_test_uptodate(folio))
-- 
2.43.0