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Subject[patch 11/11] mm: Reimplementation of dynamic per-cpu allocator -- hotplug_alloc_percpu_blocks
Patch to hotplug chunks of memory for alloc_percpu blocks when a cpu comes
up. This is needed when alloc_percpu is used real early and the
cpu_possible mask is not fully setup. Then, the backing chunks of memory
are allocated when cpus come up.

Signed-off-by: Alok N Kataria <alokk@calsoftinc.com>
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Shai Fultheim <shai@scalex86.org>

Index: alloc_percpu-2.6.13/include/linux/percpu.h
===================================================================
--- alloc_percpu-2.6.13.orig/include/linux/percpu.h 2005-09-12 12:23:34.000000000 -0700
+++ alloc_percpu-2.6.13/include/linux/percpu.h 2005-09-12 18:39:42.000000000 -0700
@@ -31,6 +31,7 @@

extern void *__alloc_percpu(size_t size, size_t align, unsigned int gfpflags);
extern void free_percpu(const void *);
+extern void __init alloc_percpu_init(void);

#else /* CONFIG_SMP */

@@ -49,6 +50,8 @@
kfree(ptr);
}

+#define alloc_percpu_init() do {} while (0)
+
#endif /* CONFIG_SMP */

/* Simple wrapper for the common case: zeros memory. */
Index: alloc_percpu-2.6.13/init/main.c
===================================================================
--- alloc_percpu-2.6.13.orig/init/main.c 2005-09-12 12:23:34.000000000 -0700
+++ alloc_percpu-2.6.13/init/main.c 2005-09-12 18:25:05.000000000 -0700
@@ -495,6 +495,9 @@
#endif
vfs_caches_init_early();
mem_init();
+
+ alloc_percpu_init();
+
kmem_cache_init();
setup_per_cpu_pageset();
numa_policy_init();
Index: alloc_percpu-2.6.13/mm/percpu.c
===================================================================
--- alloc_percpu-2.6.13.orig/mm/percpu.c 2005-09-12 12:23:34.000000000 -0700
+++ alloc_percpu-2.6.13/mm/percpu.c 2005-09-12 16:57:49.000000000 -0700
@@ -35,8 +35,9 @@
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/mm.h>
-
#include <linux/sort.h>
+#include <linux/notifier.h>
+#include <linux/cpu.h>
#ifdef CONFIG_HIGHMEM
#include <asm/highmem.h>
#endif
@@ -200,8 +201,10 @@
rollback_pages:
j--;
for (; j >= 0; j--)
- if (cpu_possible(j / cpu_pages))
+ if (cpu_possible(j / cpu_pages)) {
__free_pages(blkp->pages[j], 0);
+ blkp->pages[j] = NULL;
+ }

/* Unmap block management */
tmp.addr = area->addr + NR_CPUS * PCPU_BLKSIZE;
@@ -222,6 +225,90 @@
return NULL;
}

+static int __devinit __allocate_chunk(int cpu, struct pcpu_block *blkp)
+{
+ unsigned int cpu_pages = PCPU_BLKSIZE >> PAGE_SHIFT;
+ int start_idx, j;
+ struct vm_struct tmp;
+ struct page **tmppage;
+
+ /* Alloc node local pages for the onlined cpu */
+ start_idx = cpu * cpu_pages;
+
+ if (blkp->pages[start_idx])
+ return 1; /* Already allocated */
+
+ for (j = start_idx; j < start_idx + cpu_pages; j++) {
+ BUG_ON(blkp->pages[j]);
+ blkp->pages[j] = alloc_pages_node(cpu_to_node(cpu),
+ GFP_ATOMIC |
+ __GFP_HIGHMEM,
+ 0);
+ if (unlikely(!blkp->pages[j]))
+ goto rollback_pages;
+ }
+
+ /* Map pages for each cpu by splitting vm_struct for each cpu */
+ tmppage = &blkp->pages[cpu * cpu_pages];
+ tmp.addr = blkp->start_addr + cpu * PCPU_BLKSIZE;
+ /* map_vm_area assumes a guard page of size PAGE_SIZE */
+ tmp.size = PCPU_BLKSIZE + PAGE_SIZE;
+ if (map_vm_area(&tmp, PAGE_KERNEL, &tmppage))
+ goto rollback_pages;
+
+ return 1; /* Success */
+
+rollback_pages:
+ j--;
+ for (; j >= 0; j--) {
+ __free_pages(blkp->pages[j], 0);
+ blkp->pages[j] = NULL;
+ }
+ return 0;
+}
+
+/* Allocate chunks for this cpu in all blocks */
+static int __devinit allocate_chunk(int cpu)
+{
+ struct pcpu_block *blkp = NULL;
+ unsigned long flags;
+ spin_lock_irqsave(&blklist_lock, flags);
+ list_for_each_entry(blkp, &blkhead, blklist) {
+ if (!__allocate_chunk(cpu, blkp)) {
+ spin_unlock_irqrestore(&blklist_lock, flags);
+ return 0;
+ }
+ }
+
+ spin_unlock_irqrestore(&blklist_lock, flags);
+ return 1;
+}
+
+
+static int __devinit alloc_percpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ long cpu = (long)hcpu;
+ switch (action) {
+ case CPU_UP_PREPARE:
+ if (!allocate_chunk(cpu))
+ return NOTIFY_BAD;
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __devinitdata alloc_percpu_nb = {
+ .notifier_call = alloc_percpu_notify,
+};
+
+void __init alloc_percpu_init(void)
+{
+ register_cpu_notifier(&alloc_percpu_nb);
+}
+
/* Free memory block allocated by valloc_percpu */
static void vfree_percpu(void *addr)
{
-
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