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authorLee Schermerhorn <Lee.Schermerhorn@hp.com>2007-09-18 22:46:47 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-09-19 11:24:18 -0700
commit480eccf9ae1073b87bb4fe118971fbf134a5bc61 (patch)
treeb66cd85cd6ad9dc7c141d34837a848111d036584 /include
parent28f300d23674fa01ae747c66ce861d4ee6aebe8c (diff)
downloadlinux-linaro-480eccf9ae1073b87bb4fe118971fbf134a5bc61.tar.gz
Fix NUMA Memory Policy Reference Counting
This patch proposes fixes to the reference counting of memory policy in the page allocation paths and in show_numa_map(). Extracted from my "Memory Policy Cleanups and Enhancements" series as stand-alone. Shared policy lookup [shmem] has always added a reference to the policy, but this was never unrefed after page allocation or after formatting the numa map data. Default system policy should not require additional ref counting, nor should the current task's task policy. However, show_numa_map() calls get_vma_policy() to examine what may be [likely is] another task's policy. The latter case needs protection against freeing of the policy. This patch adds a reference count to a mempolicy returned by get_vma_policy() when the policy is a vma policy or another task's mempolicy. Again, shared policy is already reference counted on lookup. A matching "unref" [__mpol_free()] is performed in alloc_page_vma() for shared and vma policies, and in show_numa_map() for shared and another task's mempolicy. We can call __mpol_free() directly, saving an admittedly inexpensive inline NULL test, because we know we have a non-NULL policy. Handling policy ref counts for hugepages is a bit trickier. huge_zonelist() returns a zone list that might come from a shared or vma 'BIND policy. In this case, we should hold the reference until after the huge page allocation in dequeue_hugepage(). The patch modifies huge_zonelist() to return a pointer to the mempolicy if it needs to be unref'd after allocation. Kernel Build [16cpu, 32GB, ia64] - average of 10 runs: w/o patch w/ refcount patch Avg Std Devn Avg Std Devn Real: 100.59 0.38 100.63 0.43 User: 1209.60 0.37 1209.91 0.31 System: 81.52 0.42 81.64 0.34 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Andi Kleen <ak@suse.de> Cc: Christoph Lameter <clameter@sgi.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mempolicy.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 5bdd656e88c..a020eb2d4e2 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -159,7 +159,7 @@ extern void mpol_fix_fork_child_flag(struct task_struct *p);
extern struct mempolicy default_policy;
extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
- unsigned long addr, gfp_t gfp_flags);
+ unsigned long addr, gfp_t gfp_flags, struct mempolicy **mpol);
extern unsigned slab_node(struct mempolicy *policy);
extern enum zone_type policy_zone;
@@ -256,7 +256,7 @@ static inline void mpol_fix_fork_child_flag(struct task_struct *p)
#define set_cpuset_being_rebound(x) do {} while (0)
static inline struct zonelist *huge_zonelist(struct vm_area_struct *vma,
- unsigned long addr, gfp_t gfp_flags)
+ unsigned long addr, gfp_t gfp_flags, struct mempolicy **mpol)
{
return NODE_DATA(0)->node_zonelists + gfp_zone(gfp_flags);
}