linux-kernel - Re: [REGRESSION] kmemleak: commit c566586818 causes failure to boot

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Message-ID: <20191014125115.GA19200@arrakis.emea.arm.com>
Date:   Mon, 14 Oct 2019 13:51:15 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [REGRESSION] kmemleak: commit c566586818 causes failure to boot

On Mon, Oct 14, 2019 at 07:50:21AM -0400, Theodore Y. Ts'o wrote:
> On Mon, Oct 14, 2019 at 08:03:14AM +0100, Catalin Marinas wrote:
> > Thanks for the report. I have a fix already:
> > 
> > http://lkml.kernel.org/r/20191004134624.46216-1-catalin.marinas@arm.com
> > 
> > I was hoping Andrew had sent it to Linus before -rc3 but it doesn't seem
> > to be in mainline yet.
> 
> Thanks for the pointer to the fix!  Does that mean that the workaround
> is to increase the kmemleak pool size?  I had been using the default
> (16000) and it seems surprising that that it wasn't enough to even get
> the kernel through a standard boot sequence.  Should we perhaps
> increase the default mempool size?

In your case, CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, so it disables itself
irrespective of the pool size and trips over the bug. Even with default
off, it still involves the clean-up since kmemleak needs to track early
allocations in case it is turned on by the kmemleak=on cmdline option.

So I think 16000 is sufficient in your case, the default-off triggered
the bug (well, unless you find in the logs "kmemleak: Memory pool empty,
consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE").

-- 
Catalin