Re: [PATCH] pidmap: Use GFP_ATOMIC to allocate page (was: Re: [00/54] 3.0.32-stable review)

From: Linus Torvalds
Date: Sun May 20 2012 - 19:36:58 EST


On Sun, May 20, 2012 at 4:22 PM, David Rientjes <rientjes@xxxxxxxxxx> wrote:
>
> I think this may be unnecessarily too late; smp_init() will rely on the
> arch-dependent cpu_up to guarantee that cpu_idle() has been called and
> sched_init_smp() seems to think we can do GFP_KERNEL.

Well, yes, we can pretty much rely on scheduling having to work at the
top of kernel_init(), since kernel_init is being run in a new thread
(and thus must have scheduled from the original thread that becomes
the first idle thread).

But I thought we might as well delay it until the system was really
up, since I wasn't entirely sure what the heck the other CPU's might
be doing. That said, I don't really care deeply, I think that anywhere
in kernel_init should be fine. I have no strong opinions, but the
current location does seem buggy.

That said, I'm not going to delay 3.4 over this (in fact, I already
tagged it locally, but haven't pushed out yet because the back-end
kernel.org machines seem to be unreachable right now). It apparently
only matters for configurations that are not really all that
realistic.

Linus
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