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authorAlexander Potapenko <glider@google.com>2021-07-23 15:50:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-07-23 17:43:28 -0700
commit235a85cb32bb123854ad31de46fdbf04c1d57cda (patch)
tree20de2e4c1293425ab5f2566e1525ef70e2981e20 /mm/kfence
parent32ae8a0669392248a92d7545a7363004543f3932 (diff)
kfence: move the size check to the beginning of __kfence_alloc()
Check the allocation size before toggling kfence_allocation_gate. This way allocations that can't be served by KFENCE will not result in waiting for another CONFIG_KFENCE_SAMPLE_INTERVAL without allocating anything. Link: https://lkml.kernel.org/r/20210714092222.1890268-1-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Suggested-by: Marco Elver <elver@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Marco Elver <elver@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: <stable@vger.kernel.org> [5.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/kfence')
-rw-r--r--mm/kfence/core.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index d7666ace9d2e..2623ff401a10 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -734,6 +734,13 @@ void kfence_shutdown_cache(struct kmem_cache *s)
void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags)
{
/*
+ * Perform size check before switching kfence_allocation_gate, so that
+ * we don't disable KFENCE without making an allocation.
+ */
+ if (size > PAGE_SIZE)
+ return NULL;
+
+ /*
* allocation_gate only needs to become non-zero, so it doesn't make
* sense to continue writing to it and pay the associated contention
* cost, in case we have a large number of concurrent allocations.
@@ -757,9 +764,6 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags)
if (!READ_ONCE(kfence_enabled))
return NULL;
- if (size > PAGE_SIZE)
- return NULL;
-
return kfence_guarded_alloc(s, size, flags);
}