RE: [patch] x86, bts: use atomic memory allocation

From: Metzger, Markus T
Date: Fri Mar 20 2009 - 12:24:10 EST


>-----Original Message-----
>From: Metzger, Markus T
>Sent: Friday, March 20, 2009 9:08 AM
>To: Ingo Molnar


>>> Ds_request_bts() needs to allocate memory. It uses GFP_KERNEL.
>>>
>>> Hw-branch-tracer calls ds_request_bts() within on_each_cpu().
>>>
>>> Use atomic memory allocation to allow it to be used in that context.
>>
>>the hw-branch-tracer still crashes during bootup. Have you tried the
>>config i sent to you, and have you tried to reproduce it? I've
>>attached another config that crashes.
>
>The first config boots OK.
>The second config boots OK with the additional changes to keep the GFP_KERNEL
>and move the ds_request_bts() calls out of the on_each_cpu() in the hw-branch-tracer.

I must have been asleep this morning.
The first config boots OK.
The second config does not boot, at all. Even if I completely disable DS support in the config.
However, with the new patches, it boots as far as with DS disabled.
It then hangs after CFA self-test.

With DS enabled and without the patches, it stops with a call trace somewhere in
the hw-branch-tracer selftest.


>I then bootet a defconfig kernel with some debugging enabled and I get the following
>message:
>[ 1.731080] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
>[ 1.731180] swapper/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
>[ 1.731180] (ds_lock){?.+...}, at: [<ffffffff8101560f>] ds_put_context+0x21/0xf3

I fixed this, as well, meanwhile.


regards,
markus.
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