+ mm-introduce-per-vma-lock-statistics.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm: introduce per-VMA lock statistics
has been added to the -mm mm-unstable branch.  Its filename is
     mm-introduce-per-vma-lock-statistics.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-per-vma-lock-statistics.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Suren Baghdasaryan <surenb@google.com>
Subject: mm: introduce per-VMA lock statistics
Date: Mon, 27 Feb 2023 09:36:27 -0800

Add a new CONFIG_PER_VMA_LOCK_STATS config option to dump extra statistics
about handling page fault under VMA lock.

Link: https://lkml.kernel.org/r/20230227173632.3292573-29-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


--- a/include/linux/vm_event_item.h~mm-introduce-per-vma-lock-statistics
+++ a/include/linux/vm_event_item.h
@@ -150,6 +150,12 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
 		DIRECT_MAP_LEVEL2_SPLIT,
 		DIRECT_MAP_LEVEL3_SPLIT,
 #endif
+#ifdef CONFIG_PER_VMA_LOCK_STATS
+		VMA_LOCK_SUCCESS,
+		VMA_LOCK_ABORT,
+		VMA_LOCK_RETRY,
+		VMA_LOCK_MISS,
+#endif
 		NR_VM_EVENT_ITEMS
 };
 
--- a/include/linux/vmstat.h~mm-introduce-per-vma-lock-statistics
+++ a/include/linux/vmstat.h
@@ -125,6 +125,12 @@ static inline void vm_events_fold_cpu(in
 #define count_vm_tlb_events(x, y) do { (void)(y); } while (0)
 #endif
 
+#ifdef CONFIG_PER_VMA_LOCK_STATS
+#define count_vm_vma_lock_event(x) count_vm_event(x)
+#else
+#define count_vm_vma_lock_event(x) do {} while (0)
+#endif
+
 #define __count_zid_vm_events(item, zid, delta) \
 	__count_vm_events(item##_NORMAL - ZONE_NORMAL + zid, delta)
 
--- a/mm/Kconfig.debug~mm-introduce-per-vma-lock-statistics
+++ a/mm/Kconfig.debug
@@ -279,3 +279,9 @@ config DEBUG_KMEMLEAK_AUTO_SCAN
 
 	  If unsure, say Y.
 
+config PER_VMA_LOCK_STATS
+	bool "Statistics for per-vma locks"
+	depends on PER_VMA_LOCK
+	default y
+	help
+	  Statistics for per-vma locks.
--- a/mm/memory.c~mm-introduce-per-vma-lock-statistics
+++ a/mm/memory.c
@@ -5273,6 +5273,7 @@ retry:
 	/* Check if the VMA got isolated after we found it */
 	if (vma->detached) {
 		vma_end_read(vma);
+		count_vm_vma_lock_event(VMA_LOCK_MISS);
 		/* The area was replaced with another one */
 		goto retry;
 	}
@@ -5281,6 +5282,7 @@ retry:
 	return vma;
 inval:
 	rcu_read_unlock();
+	count_vm_vma_lock_event(VMA_LOCK_ABORT);
 	return NULL;
 }
 #endif /* CONFIG_PER_VMA_LOCK */
--- a/mm/vmstat.c~mm-introduce-per-vma-lock-statistics
+++ a/mm/vmstat.c
@@ -1399,6 +1399,12 @@ const char * const vmstat_text[] = {
 	"direct_map_level2_splits",
 	"direct_map_level3_splits",
 #endif
+#ifdef CONFIG_PER_VMA_LOCK_STATS
+	"vma_lock_success",
+	"vma_lock_abort",
+	"vma_lock_retry",
+	"vma_lock_miss",
+#endif
 #endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
 };
 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA || CONFIG_MEMCG */
_

Patches currently in -mm which might be from surenb@google.com are

mm-introduce-config_per_vma_lock.patch
mm-move-mmap_lock-assert-function-definitions.patch
mm-add-per-vma-lock-and-helper-functions-to-control-it.patch
mm-mark-vma-as-being-written-when-changing-vm_flags.patch
mm-mmap-move-vma_prepare-before-vma_adjust_trans_huge.patch
mm-khugepaged-write-lock-vma-while-collapsing-a-huge-page.patch
mm-mmap-write-lock-vmas-in-vma_prepare-before-modifying-them.patch
mm-mremap-write-lock-vma-while-remapping-it-to-a-new-address-range.patch
mm-write-lock-vmas-before-removing-them-from-vma-tree.patch
mm-conditionally-write-lock-vma-in-free_pgtables.patch
kernel-fork-assert-no-vma-readers-during-its-destruction.patch
mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration.patch
mm-introduce-vma-detached-flag.patch
mm-introduce-lock_vma_under_rcu-to-be-used-from-arch-specific-code.patch
mm-fall-back-to-mmap_lock-if-vma-anon_vma-is-not-yet-set.patch
mm-add-fault_flag_vma_lock-flag.patch
mm-prevent-do_swap_page-from-handling-page-faults-under-vma-lock.patch
mm-prevent-userfaults-to-be-handled-under-per-vma-lock.patch
mm-introduce-per-vma-lock-statistics.patch
x86-mm-try-vma-lock-based-page-fault-handling-first.patch
arm64-mm-try-vma-lock-based-page-fault-handling-first.patch
mm-mmap-free-vm_area_struct-without-call_rcu-in-exit_mmap.patch
mm-separate-vma-lock-from-vm_area_struct.patch
per-vma-locks.patch