lkml.org 
[lkml]   [2017]   [Oct]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH] vmalloc: add __alloc_vm_area() for optimizing vmap stack
From
Date
This same as __vmalloc_node_range() but returns vm_struct rather than
virtual address. This allows to kill one call of find_vm_area() for
each task stack allocation for CONFIG_VMAP_STACK=y.

And fix comment about that task holds cache of vm area: this cache used
for retrieving actual stack pages, freeing is done by vfree_deferred().

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
include/linux/vmalloc.h | 6 ++++++
kernel/fork.c | 26 ++++++++++----------------
mm/vmalloc.c | 33 ++++++++++++++++++++++++++++++++-
3 files changed, 48 insertions(+), 17 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 2d92dd002abd..ce94ab55d1d6 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -130,6 +130,12 @@ extern struct vm_struct *__get_vm_area_caller(unsigned long size,
unsigned long flags,
unsigned long start, unsigned long end,
const void *caller);
+extern struct vm_struct *__alloc_vm_area(unsigned long size,
+ unsigned long align,
+ unsigned long start, unsigned long end,
+ gfp_t gfp_mask, pgprot_t prot,
+ unsigned long vm_flags, int node,
+ const void *caller);
extern struct vm_struct *remove_vm_area(const void *addr);
extern struct vm_struct *find_vm_area(const void *addr);

diff --git a/kernel/fork.c b/kernel/fork.c
index e702cb9ffbd8..c4ff0303b7c5 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -204,12 +204,10 @@ static int free_vm_stack_cache(unsigned int cpu)
static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
{
#ifdef CONFIG_VMAP_STACK
- void *stack;
+ struct vm_struct *s;
int i;

for (i = 0; i < NR_CACHED_STACKS; i++) {
- struct vm_struct *s;
-
s = this_cpu_xchg(cached_stacks[i], NULL);

if (!s)
@@ -219,20 +217,16 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
return s->addr;
}

- stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
- VMALLOC_START, VMALLOC_END,
- THREADINFO_GFP,
- PAGE_KERNEL,
- 0, node, __builtin_return_address(0));
+ s = __alloc_vm_area(THREAD_SIZE, THREAD_ALIGN,
+ VMALLOC_START, VMALLOC_END,
+ THREADINFO_GFP, PAGE_KERNEL,
+ 0, node, __builtin_return_address(0));
+ if (unlikely(!s))
+ return NULL;

- /*
- * We can't call find_vm_area() in interrupt context, and
- * free_thread_stack() can be called in interrupt context,
- * so cache the vm_struct.
- */
- if (stack)
- tsk->stack_vm_area = find_vm_area(stack);
- return stack;
+ /* Cache the vm_struct for stack to page conversions. */
+ tsk->stack_vm_area = s;
+ return s->addr;
#else
struct page *page = alloc_pages_node(node, THREADINFO_GFP,
THREAD_SIZE_ORDER);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 8a43db6284eb..456652c0660f 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1750,6 +1750,37 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
const void *caller)
{
struct vm_struct *area;
+
+ area = __alloc_vm_area(size, align, start, end, gfp_mask,
+ prot, vm_flags, node, caller);
+
+ return area ? area->addr : NULL;
+}
+
+/**
+ * __alloc_vm_area - allocate virtually contiguous memory
+ * @size: allocation size
+ * @align: desired alignment
+ * @start: vm area range start
+ * @end: vm area range end
+ * @gfp_mask: flags for the page level allocator
+ * @prot: protection mask for the allocated pages
+ * @vm_flags: additional vm area flags (e.g. %VM_NO_GUARD)
+ * @node: node to use for allocation or NUMA_NO_NODE
+ * @caller: caller's return address
+ *
+ * Allocate enough pages to cover @size from the page level
+ * allocator with @gfp_mask flags. Map them into contiguous
+ * kernel virtual space, using a pagetable protection of @prot
+ *
+ * Returns the area descriptor on success or %NULL on failure.
+ */
+struct vm_struct *__alloc_vm_area(unsigned long size, unsigned long align,
+ unsigned long start, unsigned long end, gfp_t gfp_mask,
+ pgprot_t prot, unsigned long vm_flags, int node,
+ const void *caller)
+{
+ struct vm_struct *area;
void *addr;
unsigned long real_size = size;

@@ -1775,7 +1806,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,

kmemleak_vmalloc(area, size, gfp_mask);

- return addr;
+ return area;

fail:
warn_alloc(gfp_mask, NULL,
\
 
 \ /
  Last update: 2017-10-06 13:36    [W:0.264 / U:0.252 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site