mm-swap-cache-swap-migration-a-d-bits-support.patch removed from -mm tree

The quilt patch titled
Subject: mm/swap: cache swap migration A/D bits support
has been removed from the -mm tree. Its filename was
mm-swap-cache-swap-migration-a-d-bits-support.patch

This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Peter Xu <[email protected]>
Subject: mm/swap: cache swap migration A/D bits support
Date: Thu, 11 Aug 2022 12:13:31 -0400

Introduce a variable swap_migration_ad_supported to cache whether the arch supports swap migration A/D bits.

Here one thing to mention is that SWP_MIG_TOTAL_BITS will internally reference the other macro MAX_PHYSMEM_BITS, which is a function call on x86 (constant on all the rest of archs).

It's safe to reference it in swapfile_init() because when reaching here we're already during initcalls level 4 so we must have initialized 5-level pgtable for x86_64 (right after early_identify_cpu() finishes).

- start_kernel
- setup_arch
- early_cpu_init
- get_cpu_cap --> fetch from CPUID (including X86_FEATURE_LA57)
- early_identify_cpu --> clear X86_FEATURE_LA57 (if early lvl5 not enabled (USE_EARLY_PGTABLE_L5))
- arch_call_rest_init
- rest_init
- kernel_init
- kernel_init_freeable
- do_basic_setup
- do_initcalls --> calls swapfile_init() (initcall level 4)

This should slightly speed up the migration swap entry handlings.

---

 include/linux/swapfile.h |    2 ++
 include/linux/swapops.h  |    7 +------
 mm/swapfile.c            |    8 ++++++++
 3 files changed, 11 insertions(+), 6 deletions(-)

@@ -12,5 +12,7 @@ unsigned long arch_max_swapfile_size(voi
 
 /* Maximum swapfile size supported for the arch (not inclusive). */
 extern unsigned long swapfile_maximum_size;
+/* Whether swap migration entry supports storing A/D bits for the arch */
+extern bool swap_migration_ad_supported;
 
 #endif /* _LINUX_SWAPFILE_H */

@@ -301,13 +301,8 @@ static inline swp_entry_t make_writable_
  */
 static inline bool migration_entry_supports_ad(void)
 {
-	/*
-	 * max_swapfile_size() returns the max supported swp-offset plus 1.
-	 * We can support the migration A/D bits iff the pfn swap entry has
-	 * the offset large enough to cover all of them (PFN, A & D bits).
-	 */
 #ifdef CONFIG_SWAP
-	return swapfile_maximum_size >= (1UL << SWP_MIG_TOTAL_BITS);
+	return swap_migration_ad_supported;
 #else  /* CONFIG_SWAP */
 	return false;
 #endif	/* CONFIG_SWAP */

@@ -64,6 +64,9 @@ EXPORT_SYMBOL_GPL(nr_swap_pages);
 long total_swap_pages;
 static int least_priority = -1;
 unsigned long swapfile_maximum_size;
+#ifdef CONFIG_MIGRATION
+bool swap_migration_ad_supported;
+#endif	/* CONFIG_MIGRATION */
 
 static const char Bad_file[] = "Bad swap file entry ";
 static const char Unused_file[] = "Unused swap file entry ";

@@ -3680,6 +3683,11 @@ static int __init swapfile_init(void)
 
 	swapfile_maximum_size = arch_max_swapfile_size();
 
+#ifdef CONFIG_MIGRATION
+	if (swapfile_maximum_size >= (1UL << SWP_MIG_TOTAL_BITS))
+		swap_migration_ad_supported = true;
+#endif	/* CONFIG_MIGRATION */
+
 	return 0;
 }
 subsys_initcall(swapfile_init);

_

Patches currently in -mm which might be from [email protected] are