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authorDave Hansen <dave.hansen@linux.intel.com>2014-06-04 16:06:37 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-04 16:53:56 -0700
commit8eae1492675d0ffc12189f8db573624413232e15 (patch)
tree922b6d5b48a6bdbfc8d9d6a1a780147618fbb6e0 /mm/slub.c
parent9a02d699935c9acdfefe431bbc33771d1d87da7f (diff)
downloadlinux-8eae1492675d0ffc12189f8db573624413232e15.tar.bz2
mm: slub: fix ALLOC_SLOWPATH stat
There used to be only one path out of __slab_alloc(), and ALLOC_SLOWPATH got bumped in that exit path. Now there are two, and a bunch of gotos. ALLOC_SLOWPATH can now get set more than once during a single call to __slab_alloc() which is pretty bogus. Here's the sequence: 1. Enter __slab_alloc(), fall through all the way to the stat(s, ALLOC_SLOWPATH); 2. hit 'if (!freelist)', and bump DEACTIVATE_BYPASS, jump to new_slab (goto #1) 3. Hit 'if (c->partial)', bump CPU_PARTIAL_ALLOC, goto redo (goto #2) 4. Fall through in the same path we did before all the way to stat(s, ALLOC_SLOWPATH) 5. bump ALLOC_REFILL stat, then return Doing this is obviously bogus. It keeps us from being able to accurately compare ALLOC_SLOWPATH vs. ALLOC_FASTPATH. It also means that the total number of allocs always exceeds the total number of frees. This patch moves stat(s, ALLOC_SLOWPATH) to be called from the same place that __slab_alloc() is. This makes it much less likely that ALLOC_SLOWPATH will get botched again in the spaghetti-code inside __slab_alloc(). Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 65a0a5c57f31..d05a5483106d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2326,8 +2326,6 @@ redo:
if (freelist)
goto load_freelist;
- stat(s, ALLOC_SLOWPATH);
-
freelist = get_freelist(s, page);
if (!freelist) {
@@ -2432,10 +2430,10 @@ redo:
object = c->freelist;
page = c->page;
- if (unlikely(!object || !node_match(page, node)))
+ if (unlikely(!object || !node_match(page, node))) {
object = __slab_alloc(s, gfpflags, node, addr, c);
-
- else {
+ stat(s, ALLOC_SLOWPATH);
+ } else {
void *next_object = get_freepointer_safe(s, object);
/*