Re: linux-2.5.40 64GB highmem BUG()

["Adam J. Richter" <adam@yggdrasil.com>]

>> 	Although 2.5.40 has been out for a while, I think I ought
>> to post this bug as I haven't seen any other mention of it.
>> 	When I boot an 2.5.40 x86 kernel built with CONFIG_HIGHMEM64G,
>> and with a 920kB initial ramdisk (2.2MB uncompressed), I get a kernel
>> BUG() at highmem.c line 480, preceded by a message saying "scheduling
>> with KM_TYPE 15 held!"  The machine on which I experienced this
>> problem has 1.25GB of RAM.  The problem occurs with and without
>> CONFIG_PREEMPT.  All kernels that tried were SMP kernels running on a
>> uniprocessor.

>This is not reproducible here with 2.5.52-mm2. Is the initrd required
>to trigger this?

	Yes, the initrd seems to be required.  It happens when
the initrd attempts to mount /proc (it runs a shell script that
starts by setting PATH, mounting /dev, and mounting /proc).

	I've verified that under 2.5.52 the problem occurs with
CONFIG_HIGHME64G and not with CONFIG_HIGHMEM4G.  Actually, now the
problem is a BUG() at slab.c:1451, which is also memory corruption,
and I suspect just an evolution of the same problem from 2.5.40.

	Anyhow, in case it helps you, I've put the vmlinux and initrd
that produce this problem in
ftp://ftp.yggdrasil.com/private/adam/for-wli/.  Note that the ramdisk
has kernel modules that don't match the kernel but that's not the
issue, as I configured that kernel to have a different version name.

       Thanks for your attention to this problem.

Adam J. Richter     __     ______________   575 Oroville Road
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