x86: remove PG_uncached

Convert x86 to use PG_arch_2 instead of PG_uncached and remove
PG_uncached.

Link: https://lkml.kernel.org/r/20240821193445.2294269-11-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/features/vm/PG_uncached/arch-support.txt

-#
-# Feature name:          PG_uncached
-#         Kconfig:       ARCH_USES_PG_UNCACHED
-#         description:   arch supports the PG_uncached page flag
-#
-    -----------------------
-    |         arch |status|
-    -----------------------
-    |       alpha: | TODO |
-    |         arc: | TODO |
-    |         arm: | TODO |
-    |       arm64: | TODO |
-    |        csky: | TODO |
-    |     hexagon: | TODO |
-    |   loongarch: | TODO |
-    |        m68k: | TODO |
-    |  microblaze: | TODO |
-    |        mips: | TODO |
-    |       nios2: | TODO |
-    |    openrisc: | TODO |
-    |      parisc: | TODO |
-    |     powerpc: | TODO |
-    |       riscv: | TODO |
-    |        s390: | TODO |
-    |          sh: | TODO |
-    |       sparc: | TODO |
-    |          um: | TODO |
-    |         x86: |  ok  |
-    |      xtensa: | TODO |
-    -----------------------

arch/arm64/Kconfig

@@ -2100,7 +2100,8 @@ config ARM64_MTE
 	depends on ARM64_PAN
 	select ARCH_HAS_SUBPAGE_FAULTS
 	select ARCH_USES_HIGH_VMA_FLAGS
-	select ARCH_USES_PG_ARCH_X
+	select ARCH_USES_PG_ARCH_2
+	select ARCH_USES_PG_ARCH_3
 	help
 	  Memory Tagging (part of the ARMv8.5 Extensions) provides
 	  architectural support for run-time, always-on detection of

arch/x86/Kconfig

@@ -1799,6 +1799,7 @@ config X86_PAT
 	def_bool y
 	prompt "x86 PAT support" if EXPERT
 	depends on MTRR
+	select ARCH_USES_PG_ARCH_2
 	help
 	  Use PAT attributes to setup page level cache control.
 
@@ -1810,10 +1811,6 @@ config X86_PAT
 
 	  If unsure, say Y.
 
-config ARCH_USES_PG_UNCACHED
-	def_bool y
-	depends on X86_PAT
-
 config X86_UMIP
 	def_bool y
 	prompt "User Mode Instruction Prevention" if EXPERT

arch/x86/mm/pat/memtype.c

@@ -104,7 +104,7 @@ __setup("debugpat", pat_debug_setup);
 
 #ifdef CONFIG_X86_PAT
 /*
- * X86 PAT uses page flags arch_1 and uncached together to keep track of
+ * X86 PAT uses page flags arch_1 and arch_2 together to keep track of
  * memory type of pages that have backing page struct.
  *
  * X86 PAT supports 4 different memory types:
@@ -118,9 +118,9 @@ __setup("debugpat", pat_debug_setup);
 
 #define _PGMT_WB		0
 #define _PGMT_WC		(1UL << PG_arch_1)
-#define _PGMT_UC_MINUS		(1UL << PG_uncached)
-#define _PGMT_WT		(1UL << PG_uncached | 1UL << PG_arch_1)
-#define _PGMT_MASK		(1UL << PG_uncached | 1UL << PG_arch_1)
+#define _PGMT_UC_MINUS		(1UL << PG_arch_2)
+#define _PGMT_WT		(1UL << PG_arch_2 | 1UL << PG_arch_1)
+#define _PGMT_MASK		(1UL << PG_arch_2 | 1UL << PG_arch_1)
 #define _PGMT_CLEAR_MASK	(~_PGMT_MASK)
 
 static inline enum page_cache_mode get_page_memtype(struct page *pg)

fs/proc/page.c

@@ -206,18 +206,16 @@ u64 stable_page_flags(const struct page *page)
 		u |= kpf_copy_bit(page->flags, KPF_HWPOISON,	PG_hwpoison);
 #endif
 
-#ifdef CONFIG_ARCH_USES_PG_UNCACHED
-	u |= kpf_copy_bit(k, KPF_UNCACHED,	PG_uncached);
-#endif
-
 	u |= kpf_copy_bit(k, KPF_RESERVED,	PG_reserved);
 	u |= kpf_copy_bit(k, KPF_OWNER_2,	PG_owner_2);
 	u |= kpf_copy_bit(k, KPF_PRIVATE,	PG_private);
 	u |= kpf_copy_bit(k, KPF_PRIVATE_2,	PG_private_2);
 	u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE,	PG_owner_priv_1);
 	u |= kpf_copy_bit(k, KPF_ARCH,		PG_arch_1);
-#ifdef CONFIG_ARCH_USES_PG_ARCH_X
+#ifdef CONFIG_ARCH_USES_PG_ARCH_2
 	u |= kpf_copy_bit(k, KPF_ARCH_2,	PG_arch_2);
+#endif
+#ifdef CONFIG_ARCH_USES_PG_ARCH_3
 	u |= kpf_copy_bit(k, KPF_ARCH_3,	PG_arch_3);
 #endif
 

include/linux/kernel-page-flags.h

@@ -15,7 +15,6 @@
 #define KPF_PRIVATE_2		36
 #define KPF_OWNER_PRIVATE	37
 #define KPF_ARCH		38
-#define KPF_UNCACHED		39
 #define KPF_SOFTDIRTY		40
 #define KPF_ARCH_2		41
 #define KPF_ARCH_3		42

include/linux/page-flags.h

@@ -113,9 +113,6 @@ enum pageflags {
 #ifdef CONFIG_MMU
 	PG_mlocked,		/* Page is vma mlocked */
 #endif
-#ifdef CONFIG_ARCH_USES_PG_UNCACHED
-	PG_uncached,		/* Page has been mapped as uncached */
-#endif
 #ifdef CONFIG_MEMORY_FAILURE
 	PG_hwpoison,		/* hardware poisoned page. Don't touch */
 #endif
@@ -123,8 +120,10 @@ enum pageflags {
 	PG_young,
 	PG_idle,
 #endif
-#ifdef CONFIG_ARCH_USES_PG_ARCH_X
+#ifdef CONFIG_ARCH_USES_PG_ARCH_2
 	PG_arch_2,
+#endif
+#ifdef CONFIG_ARCH_USES_PG_ARCH_3
 	PG_arch_3,
 #endif
 	__NR_PAGEFLAGS,
@@ -602,12 +601,6 @@ FOLIO_FLAG_FALSE(mlocked)
 	FOLIO_TEST_SET_FLAG_FALSE(mlocked)
 #endif
 
-#ifdef CONFIG_ARCH_USES_PG_UNCACHED
-PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
-#else
-PAGEFLAG_FALSE(Uncached, uncached)
-#endif
-
 #ifdef CONFIG_MEMORY_FAILURE
 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)

include/trace/events/mmflags.h

@@ -71,12 +71,6 @@
 #define IF_HAVE_PG_MLOCK(_name)
 #endif
 
-#ifdef CONFIG_ARCH_USES_PG_UNCACHED
-#define IF_HAVE_PG_UNCACHED(_name) ,{1UL << PG_##_name, __stringify(_name)}
-#else
-#define IF_HAVE_PG_UNCACHED(_name)
-#endif
-
 #ifdef CONFIG_MEMORY_FAILURE
 #define IF_HAVE_PG_HWPOISON(_name) ,{1UL << PG_##_name, __stringify(_name)}
 #else
@@ -89,10 +83,16 @@
 #define IF_HAVE_PG_IDLE(_name)
 #endif
 
-#ifdef CONFIG_ARCH_USES_PG_ARCH_X
-#define IF_HAVE_PG_ARCH_X(_name) ,{1UL << PG_##_name, __stringify(_name)}
+#ifdef CONFIG_ARCH_USES_PG_ARCH_2
+#define IF_HAVE_PG_ARCH_2(_name) ,{1UL << PG_##_name, __stringify(_name)}
+#else
+#define IF_HAVE_PG_ARCH_2(_name)
+#endif
+
+#ifdef CONFIG_ARCH_USES_PG_ARCH_3
+#define IF_HAVE_PG_ARCH_3(_name) ,{1UL << PG_##_name, __stringify(_name)}
 #else
-#define IF_HAVE_PG_ARCH_X(_name)
+#define IF_HAVE_PG_ARCH_3(_name)
 #endif
 
 #define DEF_PAGEFLAG_NAME(_name) { 1UL <<  PG_##_name, __stringify(_name) }
@@ -118,12 +118,11 @@
 	DEF_PAGEFLAG_NAME(swapbacked),					\
 	DEF_PAGEFLAG_NAME(unevictable)					\
 IF_HAVE_PG_MLOCK(mlocked)						\
-IF_HAVE_PG_UNCACHED(uncached)						\
 IF_HAVE_PG_HWPOISON(hwpoison)						\
 IF_HAVE_PG_IDLE(idle)							\
 IF_HAVE_PG_IDLE(young)							\
-IF_HAVE_PG_ARCH_X(arch_2)						\
-IF_HAVE_PG_ARCH_X(arch_3)
+IF_HAVE_PG_ARCH_2(arch_2)						\
+IF_HAVE_PG_ARCH_3(arch_3)
 
 #define show_page_flags(flags)						\
 	(flags) ? __print_flags(flags, "|",				\

mm/Kconfig

@@ -1079,13 +1079,10 @@ config ARCH_USES_HIGH_VMA_FLAGS
 config ARCH_HAS_PKEYS
 	bool
 
-config ARCH_USES_PG_ARCH_X
+config ARCH_USES_PG_ARCH_2
+	bool
+config ARCH_USES_PG_ARCH_3
 	bool
-	help
-	  Enable the definition of PG_arch_x page flags with x > 1. Only
-	  suitable for 64-bit architectures with CONFIG_FLATMEM or
-	  CONFIG_SPARSEMEM_VMEMMAP enabled, otherwise there may not be
-	  enough room for additional bits in page->flags.
 
 config VM_EVENT_COUNTERS
 	default y

mm/huge_memory.c

@@ -2993,8 +2993,10 @@ static void __split_huge_page_tail(struct folio *folio, int tail,
 			 (1L << PG_workingset) |
 			 (1L << PG_locked) |
 			 (1L << PG_unevictable) |
-#ifdef CONFIG_ARCH_USES_PG_ARCH_X
+#ifdef CONFIG_ARCH_USES_PG_ARCH_2
 			 (1L << PG_arch_2) |
+#endif
+#ifdef CONFIG_ARCH_USES_PG_ARCH_3
 			 (1L << PG_arch_3) |
 #endif
 			 (1L << PG_dirty) |

tools/mm/page-types.c

@@ -76,7 +76,7 @@
 #define KPF_PRIVATE_2		36
 #define KPF_OWNER_PRIVATE	37
 #define KPF_ARCH		38
-#define KPF_UNCACHED		39
+#define KPF_UNCACHED		39	/* unused */
 #define KPF_SOFTDIRTY		40
 #define KPF_ARCH_2		41
 
@@ -134,7 +134,6 @@ static const char * const page_flag_names[] = {
 	[KPF_PRIVATE_2]		= "p:private_2",
 	[KPF_OWNER_PRIVATE]	= "O:owner_private",
 	[KPF_ARCH]		= "h:arch",
-	[KPF_UNCACHED]		= "c:uncached",
 	[KPF_SOFTDIRTY]		= "f:softdirty",
 	[KPF_ARCH_2]		= "H:arch_2",