lkml.org 
[lkml]   [2005]   [Sep]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch 10/11] mm: Reimplementation of dynamic per-cpu allocator -- allow_early_mapvmarea
This patch provides for early calls to map_vm_area.  Currently, map_vm_area
cannot be called early during the boot process since map_vm_area depends on
kmalloc for the vm_struct objects. This patch is a bad hack to let
map_vm_area work early, but just for a few calls so that the dynamic per-cpu
subsystem can allocate a block and satisfy some early requests. This is
primarily to enable slab code use alloc_percpu for slab head arrays. This
patch might not be elegant, but solves the chicken and egg problem in using
alloc_percpu for slab.

Signed-off-by: Ravikiran Thirumalai <kiran.th@gmail.com>

Index: alloc_percpu-2.6.13-rc6/include/linux/slab.h
===================================================================
--- alloc_percpu-2.6.13-rc6.orig/include/linux/slab.h 2005-08-14 21:47:56.000000000 -0700
+++ alloc_percpu-2.6.13-rc6/include/linux/slab.h 2005-08-15 17:29:41.000000000 -0700
@@ -76,6 +76,8 @@
extern struct cache_sizes malloc_sizes[];
extern void *__kmalloc(size_t, unsigned int __nocast);

+#define SLAB_READY ({malloc_sizes[0].cs_cachep != NULL;})
+
static inline void *kmalloc(size_t size, unsigned int __nocast flags)
{
if (__builtin_constant_p(size)) {
Index: alloc_percpu-2.6.13-rc6/include/linux/vmalloc.h
===================================================================
--- alloc_percpu-2.6.13-rc6.orig/include/linux/vmalloc.h 2005-08-15 17:28:42.000000000 -0700
+++ alloc_percpu-2.6.13-rc6/include/linux/vmalloc.h 2005-08-15 17:29:41.000000000 -0700
@@ -8,6 +8,7 @@
#define VM_IOREMAP 0x00000001 /* ioremap() and friends */
#define VM_ALLOC 0x00000002 /* vmalloc() */
#define VM_MAP 0x00000004 /* vmap()ed pages */
+#define VM_EARLY 0x00000008 /* indicates static vm_struct */
/* bits [20..32] reserved for arch specific ioremap internals */

struct vm_struct {
Index: alloc_percpu-2.6.13-rc6/mm/vmalloc.c
===================================================================
--- alloc_percpu-2.6.13-rc6.orig/mm/vmalloc.c 2005-08-15 17:28:42.000000000 -0700
+++ alloc_percpu-2.6.13-rc6/mm/vmalloc.c 2005-08-15 17:35:29.000000000 -0700
@@ -160,6 +160,15 @@

#define IOREMAP_MAX_ORDER (7 + PAGE_SHIFT) /* 128 pages */

+/*
+ * Statically define a few vm_structs so that early per-cpu allocator code
+ * can get vm_areas even before slab is up. NR_EARLY_VMAREAS should remain
+ * in single digits
+ */
+#define NR_EARLY_VMAREAS (1)
+static struct vm_struct early_vmareas[NR_EARLY_VMAREAS];
+static int early_vmareas_idx = 0;
+
struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
unsigned long start, unsigned long end,
unsigned int gfp_flags)
@@ -168,6 +177,9 @@
unsigned long align = 1;
unsigned long addr;

+ if (unlikely(!size))
+ return NULL;
+
if (flags & VM_IOREMAP) {
int bit = fls(size);

@@ -184,10 +196,16 @@
area = kmalloc(sizeof(*area), gfp_flags);
if (unlikely(!area))
return NULL;
-
- if (unlikely(!size)) {
- kfree (area);
- return NULL;
+ if (likely(SLAB_READY)) {
+ area = kmalloc(sizeof(*area), GFP_KERNEL);
+ if (unlikely(!area))
+ return NULL;
+ } else {
+ if (early_vmareas_idx < NR_EARLY_VMAREAS) {
+ area = &early_vmareas[early_vmareas_idx++];
+ flags |= VM_EARLY;
+ } else
+ return NULL;
}

/*
@@ -228,7 +246,8 @@

out:
write_unlock(&vmlist_lock);
- kfree(area);
+ if (likely(!(flags & VM_EARLY)))
+ kfree(area);
if (printk_ratelimit())
printk(KERN_WARNING "allocation failed: out of vmalloc space - use vmalloc=<size> to increase size.\n");
return NULL;
@@ -326,7 +345,8 @@
kfree(area->pages);
}

- kfree(area);
+ if (likely(!(area->flags & VM_EARLY)))
+ kfree(area);
return;
}

@@ -415,7 +435,8 @@
area->pages = pages;
if (!area->pages) {
remove_vm_area(area->addr);
- kfree(area);
+ if (likely(!(area->flags & VM_EARLY)))
+ kfree(area);
return NULL;
}
memset(area->pages, 0, array_size);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2005-09-13 18:21    [from the cache]
©2003-2011 Jasper Spaans