linux-kernel - Re: [PATCH 6/6] mm: Postpone the disabling of kmemleak early logging

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Message-ID: <20140506170549.GM23957@arm.com>
Date:	Tue, 6 May 2014 18:05:49 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 6/6] mm: Postpone the disabling of kmemleak early logging

On Tue, May 06, 2014 at 04:20:27PM +0100, Sasha Levin wrote:
> On 05/02/2014 09:41 AM, Catalin Marinas wrote:
> > Currently, kmemleak_early_log is disabled at the beginning of the
> > kmemleak_init() function, before the full kmemleak tracing is actually
> > enabled. In this small window, kmem_cache_create() is called by kmemleak
> > which triggers additional memory allocation that are not traced. This
> > patch moves the kmemleak_early_log disabling further down and at the
> > same time with full kmemleak enabling.
> > 
> > Signed-off-by: Catalin Marinas <catalin.marinas@....com>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> 
> This patch makes the kernel die during the boot process:
> 
> [   24.471801] BUG: unable to handle kernel paging request at ffffffff922f2b93
> [   24.472496] IP: [<ffffffff922f2b93>] log_early+0x0/0xcd

Thanks for reporting this. I assume you run with
CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF enabled and kmemleak_early_log remains
set even though kmemleak is not in use.

Does the patch below fix it?

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 0cd6aabd45a0..e7f74091c024 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1811,6 +1811,7 @@ void __init kmemleak_init(void)
 
 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
 	if (!kmemleak_skip_disable) {
+		kmemleak_early_log = 0;
 		kmemleak_disable();
 		return;
 	}

Thanks.

-- 
Catalin
--
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