linux-kernel - Re: [PATCH] kmemleak: Always register debugfs file

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Date:   Fri, 24 Aug 2018 16:23:46 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Vincent Whitchurch <vincent.whitchurch@...s.com>
Cc:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Vincent Whitchurch <rabinv@...s.com>
Subject: Re: [PATCH] kmemleak: Always register debugfs file

On Fri, Aug 24, 2018 at 03:12:20PM +0200, Vincent Whitchurch wrote:
> If kmemleak built in to the kernel, but is disabled by default, the
> debugfs file is never registered.  Because of this, it is not possible
> to find out if the kernel is built with kmemleak support by checking for
> the presence of this file.  To allow this, always register the file.
> 
> After this patch, if the file doesn't exist, kmemleak is not available
> in the kernel.  If writing "scan" or any other value than "clear" to
> this file results in EBUSY, then kmemleak is available but is disabled
> by default and can be activated via the kernel command line.
> 
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>

I think that's also consistent with a late disabling of kmemleak when
the debugfs entry sticks around.

Acked-by: Catalin Marinas <catalin.marinas@....com>