From: Alexander Potapenko <glider@google.com>
To: akpm@linux-foundation.org
Cc: dvyukov@google.com, elver@google.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
stable@vger.kernel.org, gregkh@linuxfoundation.org,
jrdr.linux@gmail.com, Alexander Potapenko <glider@google.com>
Subject: [PATCH v4 1/2] kfence: move the size check to the beginning of __kfence_alloc()
Date: Wed, 30 Jun 2021 17:02:33 +0200 [thread overview]
Message-ID: <20210630150234.1109496-1-glider@google.com> (raw)
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.
Suggested-by: Marco Elver <elver@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
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: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>
---
mm/kfence/core.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 4d21ac44d5d35..33bb20d91bf6a 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -733,6 +733,13 @@ 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
@@ -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);
}
--
2.32.0.93.g670b81a890-goog
next reply other threads:[~2021-06-30 15:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-30 15:02 Alexander Potapenko [this message]
2021-06-30 15:02 ` [PATCH v4 2/2] kfence: skip all GFP_ZONEMASK allocations Alexander Potapenko
2021-07-05 14:05 ` Marco Elver
2021-07-13 16:19 ` Marco Elver
2021-07-05 18:38 ` Souptick Joarder
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