From: Marco Elver <elver@google.com>
To: elver@google.com, Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Aleksandr Nogikh <nogikh@google.com>,
Taras Madan <tarasmadan@google.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kasan-dev@googlegroups.com
Subject: [PATCH 3/3] kfence: add note to documentation about skipping covered allocations
Date: Fri, 17 Sep 2021 13:07:56 +0200 [thread overview]
Message-ID: <20210917110756.1121272-3-elver@google.com> (raw)
In-Reply-To: <20210917110756.1121272-1-elver@google.com>
Add a note briefly mentioning the new policy about "skipping currently
covered allocations if pool close to full." Since this has a notable
impact on KFENCE's bug-detection ability on systems with large uptimes,
it is worth pointing out the feature.
Signed-off-by: Marco Elver <elver@google.com>
---
Documentation/dev-tools/kfence.rst | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/Documentation/dev-tools/kfence.rst b/Documentation/dev-tools/kfence.rst
index 0fbe3308bf37..e698234999d6 100644
--- a/Documentation/dev-tools/kfence.rst
+++ b/Documentation/dev-tools/kfence.rst
@@ -269,6 +269,14 @@ tail of KFENCE's freelist, so that the least recently freed objects are reused
first, and the chances of detecting use-after-frees of recently freed objects
is increased.
+If pool utilization reaches 75% or above, to reduce the probability of the pool
+containing ~100% allocated objects yet ensure diverse coverage of allocations,
+KFENCE limits currently covered allocations of the same source from further
+filling up the pool. A side-effect is that this also limits frequent long-lived
+allocations of the same source filling up the pool permanently, thereby
+reducing the risk of the pool becoming full and the sampled allocation rate
+dropping to zero.
+
Interface
---------
--
2.33.0.464.g1972c5931b-goog
next prev parent reply other threads:[~2021-09-17 11:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-17 11:07 [PATCH 1/3] kfence: count unexpectedly skipped allocations Marco Elver
2021-09-17 11:07 ` Marco Elver
2021-09-17 11:07 ` [PATCH 2/3] kfence: limit currently covered allocations when pool nearly full Marco Elver
2021-09-17 11:07 ` Marco Elver
2021-09-17 13:52 ` Dmitry Vyukov
2021-09-17 13:52 ` Dmitry Vyukov
2021-09-17 15:04 ` Marco Elver
2021-09-17 15:04 ` Marco Elver
2021-09-17 11:07 ` Marco Elver [this message]
2021-09-17 11:07 ` [PATCH 3/3] kfence: add note to documentation about skipping covered allocations Marco Elver
2021-09-17 12:58 ` [PATCH 1/3] kfence: count unexpectedly skipped allocations Dmitry Vyukov
2021-09-17 12:58 ` Dmitry Vyukov
2021-09-17 13:08 ` Marco Elver
2021-09-17 13:08 ` Marco Elver
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