Move slab_should_failslab() check from SLAB allocator to generic
slab_pre_alloc_hook(). The check guards against slab alloc
fault-injects failures for the bootstrap slab that is used for
allocating "kmem_cache" objects to the allocator itself.
I'm not really happy with this code...
---
mm/failslab.c | 2 ++
mm/slab.c | 8 --------
mm/slab.h | 23 ++++++++++++++++++++++-
3 files changed, 24 insertions(+), 9 deletions(-)
diff --git a/mm/failslab.c b/mm/failslab.c
index 79171b4a5826..a2ad28ba696c 100644
--- a/mm/failslab.c
+++ b/mm/failslab.c
@@ -13,6 +13,8 @@ static struct {
bool should_failslab(size_t size, gfp_t gfpflags, unsigned long cache_flags)
{
+ // Should we place bootstrap kmem_cache check here???
+
if (gfpflags & __GFP_NOFAIL)
return false;
diff --git a/mm/slab.c b/mm/slab.c
index 4765c97ce690..4684c2496982 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2917,14 +2917,6 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
#define cache_alloc_debugcheck_after(a,b,objp,d) (objp)
#endif
-static bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags)
-{
- if (unlikely(cachep == kmem_cache))
- return false;
-
- return should_failslab(cachep->object_size, flags, cachep->flags);
-}
-
static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
{
void *objp;
diff --git a/mm/slab.h b/mm/slab.h
index 588bc5281fc8..4e7b0e62f3f4 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -360,6 +360,27 @@ static inline size_t slab_ksize(const struct kmem_cache *s)
}
#endif
+/* FIXME: This construct sucks, because this compare+branch needs to
+ * get removed by compiler then !CONFIG_FAILSLAB (maybe compiler is
+ * smart enough to realize only "false" can be generated).
+ *
+ * Comments please: Pulling out CONFIG_FAILSLAB here looks ugly...
+ * should we instead change API of should_failslab() ??
+ *
+ * Next question: is the bootstrap cache check okay to add for all
+ * allocators? (this would be the easiest, else need more ugly ifdef's)
+ */
+static inline bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags)
+{
+ /* No fault-injection for bootstrap cache */
+#ifdef CONFIG_FAILSLAB
+ if (unlikely(cachep == kmem_cache))
+ return false;
+#endif
+
+ return should_failslab(cachep->object_size, flags, cachep->flags);
+}
+
static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
gfp_t flags)
{
@@ -367,7 +388,7 @@ static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
lockdep_trace_alloc(flags);
might_sleep_if(gfpflags_allow_blocking(flags));
- if (should_failslab(s->object_size, flags, s->flags))
+ if (slab_should_failslab(s, flags))
return NULL;
return memcg_kmem_get_cache(s, flags);
--
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