mmap: avoid unnecessary anon_vma lock

[platform/adaptation/renesas_rcar/renesas_kernel.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index 772140c..15b1fae 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -84,10 +84,14 @@ pgprot_t vm_get_page_prot(unsigned long vm_flags)
 }
 EXPORT_SYMBOL(vm_get_page_prot);
 
-int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
-int sysctl_overcommit_ratio = 50;      /* default is 50% */
+int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;  /* heuristic overcommit */
+int sysctl_overcommit_ratio __read_mostly = 50;        /* default is 50% */
 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
-struct percpu_counter vm_committed_as;
+/*
+ * Make sure vm_committed_as in one cacheline and not cacheline shared with
+ * other variables. It can be updated by several CPUs frequently.
+ */
+struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
 
 /*
  * Check that a process has enough memory to allocate a new virtual
@@ -605,7 +609,7 @@ again:                      remove_next = 1 + (end > next->vm_end);
         * lock may be shared between many sibling processes.  Skipping
         * the lock for brk adjustments makes a difference sometimes.
         */
-       if (vma->anon_vma && (insert || importer || start != vma->vm_start)) {
+       if (vma->anon_vma && (importer || start != vma->vm_start)) {
                anon_vma = vma->anon_vma;
                anon_vma_lock(anon_vma);
        }