If call kmalloc_node with NO __GFP_THISNODE and node[A] with no memory.
Slub will alloc a slub page which is not belong to A, and put the page
to kmem_cache_node[page_to_nid(page)]. The page can not be reused
at next calling, because NULL will be get from get_partical().
That make kmalloc_node consume more memory.
On qemu with 4 numas and each numa has 1G memory, Write a test ko
to call kmalloc_node(196, 0xd20c0, 3) for 5 * 1024 * 1024 times.
cat /proc/slabinfo shows:
kmalloc-256 4302317 15151808 256 32 2 : tunables..
the total objects is much more then active objects.
After this patch, cat /prac/slubinfo shows:
kmalloc-256 5244950 5245088 256 32 2 : tunables..
Signed-off-by: Chen Jun <chenjun102@xxxxxxxxxx>
---
mm/slub.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 39327e98fce3..c0090a5de54e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2384,7 +2384,7 @@ static void *get_partial(struct kmem_cache *s, int node, struct partial_context
searchnode = numa_mem_id();
object = get_partial_node(s, get_node(s, searchnode), pc);
- if (object || node != NUMA_NO_NODE)
+ if (object || (node != NUMA_NO_NODE && (pc->flags & __GFP_THISNODE)))
return object;
return get_any_partial(s, pc);
@@ -3069,6 +3069,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
struct slab *slab;
unsigned long flags;
struct partial_context pc;
+ int try_thisndoe = 0;
stat(s, ALLOC_SLOWPATH);
@@ -3181,8 +3182,12 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
}
new_objects:
-
pc.flags = gfpflags;
+
+ /* Try to get page from specific node even if __GFP_THISNODE is not set */
+ if (node != NUMA_NO_NODE && !(gfpflags & __GFP_THISNODE) && try_thisnode)
+ pc.flags |= __GFP_THISNODE;
+
pc.slab = &slab;
pc.orig_size = orig_size;
freelist = get_partial(s, node, &pc);
@@ -3190,10 +3195,16 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
goto check_new_slab;
slub_put_cpu_ptr(s->cpu_slab);
- slab = new_slab(s, gfpflags, node);
+ slab = new_slab(s, pc.flags, node);
c = slub_get_cpu_ptr(s->cpu_slab);
if (unlikely(!slab)) {
+ /* Try to get page from any other node */
+ if (node != NUMA_NO_NODE && !(gfpflags & __GFP_THISNODE) && try_thisnode) {
+ try_thisnode = 0;
+ goto new_objects;
+ }
+
slab_out_of_memory(s, gfpflags, node);
return NULL;
}
--
2.17.1
