From: David Rientjes <rientjes@google.com>
To: Marco Elver <elver@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Dmitry Vyukov <dvyukov@google.com>,
Alexander Potapenko <glider@google.com>,
kasan-dev@googlegroups.com, Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH] mm/slab_common: use WARN() if cache still has objects on destroy
Date: Tue, 9 Nov 2021 17:49:14 -0800 (PST) [thread overview]
Message-ID: <146e59b4-76c-69e4-969-ce8a75ccfe5d@google.com> (raw)
In-Reply-To: <20211102170733.648216-1-elver@google.com>
On Tue, 2 Nov 2021, Marco Elver wrote:
> Calling kmem_cache_destroy() while the cache still has objects allocated
> is a kernel bug, and will usually result in the entire cache being
> leaked. While the message in kmem_cache_destroy() resembles a warning,
> it is currently not implemented using a real WARN().
>
> This is problematic for infrastructure testing the kernel, all of which
> rely on the specific format of WARN()s to pick up on bugs.
>
> Some 13 years ago this used to be a simple WARN_ON() in slub, but
> d629d8195793 ("slub: improve kmem_cache_destroy() error message")
> changed it into an open-coded warning to avoid confusion with a bug in
> slub itself.
>
> Instead, turn the open-coded warning into a real WARN() with the message
> preserved, so that test systems can actually identify these issues, and
> we get all the other benefits of using a normal WARN(). The warning
> message is extended with "when called from <caller-ip>" to make it even
> clearer where the fault lies.
>
> For most configurations this is only a cosmetic change, however, note
> that WARN() here will now also respect panic_on_warn.
>
> Signed-off-by: Marco Elver <elver@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Thanks Marco!
prev parent reply other threads:[~2021-11-10 1:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-02 17:07 [PATCH] mm/slab_common: use WARN() if cache still has objects on destroy Marco Elver
2021-11-03 7:23 ` Vlastimil Babka
2021-11-10 1:49 ` David Rientjes [this message]
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