linux-kernel - [PATCH] kasan, doc: note kasan.fault=panic_on

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Message-ID: <ZJHfL6vavKUZ3Yd8@elver.google.com>
Date:   Tue, 20 Jun 2023 19:17:35 +0200
From:   Marco Elver <elver@...gle.com>
To:     Andrey Konovalov <andreyknvl@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Taras Madan <tarasmadan@...gle.com>,
        Aleksandr Nogikh <nogikh@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Jonathan Corbet <corbet@....net>, kasan-dev@...glegroups.com,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Catalin Marinas <catalin.marinas@....com>
Subject: [PATCH] kasan, doc: note kasan.fault=panic_on_write behaviour for
 async modes

Note the behaviour of kasan.fault=panic_on_write for async modes, since
all asynchronous faults will result in panic (even if they are reads).

Fixes: 452c03fdbed0 ("kasan: add support for kasan.fault=panic_on_write")
Signed-off-by: Marco Elver <elver@...gle.com>
---
 Documentation/dev-tools/kasan.rst | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index 7f37a46af574..f4acf9c2e90f 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -110,7 +110,9 @@ parameter can be used to control panic and reporting behaviour:
 - ``kasan.fault=report``, ``=panic``, or ``=panic_on_write`` controls whether
   to only print a KASAN report, panic the kernel, or panic the kernel on
   invalid writes only (default: ``report``). The panic happens even if
-  ``kasan_multi_shot`` is enabled.
+  ``kasan_multi_shot`` is enabled. Note that when using asynchronous mode of
+  Hardware Tag-Based KASAN, ``kasan.fault=panic_on_write`` always panics on
+  asynchronously checked accesses (including reads).
 
 Software and Hardware Tag-Based KASAN modes (see the section about various
 modes below) support altering stack trace collection behavior:
-- 
2.41.0.185.g7c58973941-goog