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Diffstat (limited to 'mm')
-rw-r--r--mm/Makefile2
-rw-r--r--mm/mmap.c55
-rw-r--r--mm/nommu.c24
-rw-r--r--mm/vmacache.c112
4 files changed, 158 insertions, 35 deletions
diff --git a/mm/Makefile b/mm/Makefile
index cdd741519ee0..23a6f7e23019 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -16,7 +16,7 @@ obj-y := filemap.o mempool.o oom_kill.o fadvise.o \
readahead.o swap.o truncate.o vmscan.o shmem.o \
util.o mmzone.o vmstat.o backing-dev.o \
mm_init.o mmu_context.o percpu.o slab_common.o \
- compaction.o balloon_compaction.o \
+ compaction.o balloon_compaction.o vmacache.o \
interval_tree.o list_lru.o workingset.o $(mmu-y)
obj-y += init-mm.o
diff --git a/mm/mmap.c b/mm/mmap.c
index 46433e137abc..b1202cf81f4b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -10,6 +10,7 @@
#include <linux/slab.h>
#include <linux/backing-dev.h>
#include <linux/mm.h>
+#include <linux/vmacache.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
@@ -681,8 +682,9 @@ __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
prev->vm_next = next = vma->vm_next;
if (next)
next->vm_prev = prev;
- if (mm->mmap_cache == vma)
- mm->mmap_cache = prev;
+
+ /* Kill the cache */
+ vmacache_invalidate(mm);
}
/*
@@ -1989,34 +1991,33 @@ EXPORT_SYMBOL(get_unmapped_area);
/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
{
- struct vm_area_struct *vma = NULL;
+ struct rb_node *rb_node;
+ struct vm_area_struct *vma;
/* Check the cache first. */
- /* (Cache hit rate is typically around 35%.) */
- vma = ACCESS_ONCE(mm->mmap_cache);
- if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
- struct rb_node *rb_node;
+ vma = vmacache_find(mm, addr);
+ if (likely(vma))
+ return vma;
- rb_node = mm->mm_rb.rb_node;
- vma = NULL;
+ rb_node = mm->mm_rb.rb_node;
+ vma = NULL;
- while (rb_node) {
- struct vm_area_struct *vma_tmp;
-
- vma_tmp = rb_entry(rb_node,
- struct vm_area_struct, vm_rb);
-
- if (vma_tmp->vm_end > addr) {
- vma = vma_tmp;
- if (vma_tmp->vm_start <= addr)
- break;
- rb_node = rb_node->rb_left;
- } else
- rb_node = rb_node->rb_right;
- }
- if (vma)
- mm->mmap_cache = vma;
+ while (rb_node) {
+ struct vm_area_struct *tmp;
+
+ tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
+
+ if (tmp->vm_end > addr) {
+ vma = tmp;
+ if (tmp->vm_start <= addr)
+ break;
+ rb_node = rb_node->rb_left;
+ } else
+ rb_node = rb_node->rb_right;
}
+
+ if (vma)
+ vmacache_update(addr, vma);
return vma;
}
@@ -2388,7 +2389,9 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
} else
mm->highest_vm_end = prev ? prev->vm_end : 0;
tail_vma->vm_next = NULL;
- mm->mmap_cache = NULL; /* Kill the cache. */
+
+ /* Kill the cache */
+ vmacache_invalidate(mm);
}
/*
diff --git a/mm/nommu.c b/mm/nommu.c
index e19482533ce3..5d3f3524bbdc 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -15,6 +15,7 @@
#include <linux/export.h>
#include <linux/mm.h>
+#include <linux/vmacache.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/file.h>
@@ -768,16 +769,23 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
*/
static void delete_vma_from_mm(struct vm_area_struct *vma)
{
+ int i;
struct address_space *mapping;
struct mm_struct *mm = vma->vm_mm;
+ struct task_struct *curr = current;
kenter("%p", vma);
protect_vma(vma, 0);
mm->map_count--;
- if (mm->mmap_cache == vma)
- mm->mmap_cache = NULL;
+ for (i = 0; i < VMACACHE_SIZE; i++) {
+ /* if the vma is cached, invalidate the entire cache */
+ if (curr->vmacache[i] == vma) {
+ vmacache_invalidate(curr->mm);
+ break;
+ }
+ }
/* remove the VMA from the mapping */
if (vma->vm_file) {
@@ -825,8 +833,8 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
struct vm_area_struct *vma;
/* check the cache first */
- vma = ACCESS_ONCE(mm->mmap_cache);
- if (vma && vma->vm_start <= addr && vma->vm_end > addr)
+ vma = vmacache_find(mm, addr);
+ if (likely(vma))
return vma;
/* trawl the list (there may be multiple mappings in which addr
@@ -835,7 +843,7 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
if (vma->vm_start > addr)
return NULL;
if (vma->vm_end > addr) {
- mm->mmap_cache = vma;
+ vmacache_update(addr, vma);
return vma;
}
}
@@ -874,8 +882,8 @@ static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
unsigned long end = addr + len;
/* check the cache first */
- vma = mm->mmap_cache;
- if (vma && vma->vm_start == addr && vma->vm_end == end)
+ vma = vmacache_find_exact(mm, addr, end);
+ if (vma)
return vma;
/* trawl the list (there may be multiple mappings in which addr
@@ -886,7 +894,7 @@ static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
if (vma->vm_start > addr)
return NULL;
if (vma->vm_end == end) {
- mm->mmap_cache = vma;
+ vmacache_update(addr, vma);
return vma;
}
}
diff --git a/mm/vmacache.c b/mm/vmacache.c
new file mode 100644
index 000000000000..d4224b397c0e
--- /dev/null
+++ b/mm/vmacache.c
@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2014 Davidlohr Bueso.
+ */
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/vmacache.h>
+
+/*
+ * Flush vma caches for threads that share a given mm.
+ *
+ * The operation is safe because the caller holds the mmap_sem
+ * exclusively and other threads accessing the vma cache will
+ * have mmap_sem held at least for read, so no extra locking
+ * is required to maintain the vma cache.
+ */
+void vmacache_flush_all(struct mm_struct *mm)
+{
+ struct task_struct *g, *p;
+
+ rcu_read_lock();
+ for_each_process_thread(g, p) {
+ /*
+ * Only flush the vmacache pointers as the
+ * mm seqnum is already set and curr's will
+ * be set upon invalidation when the next
+ * lookup is done.
+ */
+ if (mm == p->mm)
+ vmacache_flush(p);
+ }
+ rcu_read_unlock();
+}
+
+/*
+ * This task may be accessing a foreign mm via (for example)
+ * get_user_pages()->find_vma(). The vmacache is task-local and this
+ * task's vmacache pertains to a different mm (ie, its own). There is
+ * nothing we can do here.
+ *
+ * Also handle the case where a kernel thread has adopted this mm via use_mm().
+ * That kernel thread's vmacache is not applicable to this mm.
+ */
+static bool vmacache_valid_mm(struct mm_struct *mm)
+{
+ return current->mm == mm && !(current->flags & PF_KTHREAD);
+}
+
+void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)
+{
+ if (vmacache_valid_mm(newvma->vm_mm))
+ current->vmacache[VMACACHE_HASH(addr)] = newvma;
+}
+
+static bool vmacache_valid(struct mm_struct *mm)
+{
+ struct task_struct *curr;
+
+ if (!vmacache_valid_mm(mm))
+ return false;
+
+ curr = current;
+ if (mm->vmacache_seqnum != curr->vmacache_seqnum) {
+ /*
+ * First attempt will always be invalid, initialize
+ * the new cache for this task here.
+ */
+ curr->vmacache_seqnum = mm->vmacache_seqnum;
+ vmacache_flush(curr);
+ return false;
+ }
+ return true;
+}
+
+struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr)
+{
+ int i;
+
+ if (!vmacache_valid(mm))
+ return NULL;
+
+ for (i = 0; i < VMACACHE_SIZE; i++) {
+ struct vm_area_struct *vma = current->vmacache[i];
+
+ if (vma && vma->vm_start <= addr && vma->vm_end > addr) {
+ BUG_ON(vma->vm_mm != mm);
+ return vma;
+ }
+ }
+
+ return NULL;
+}
+
+#ifndef CONFIG_MMU
+struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ int i;
+
+ if (!vmacache_valid(mm))
+ return NULL;
+
+ for (i = 0; i < VMACACHE_SIZE; i++) {
+ struct vm_area_struct *vma = current->vmacache[i];
+
+ if (vma && vma->vm_start == start && vma->vm_end == end)
+ return vma;
+ }
+
+ return NULL;
+}
+#endif
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-15 14:00:14 +0000