Re: [PATCH 0/2] Ajust lockdep static allocations

From: Babu Moger
Date: Fri Sep 23 2016 - 15:58:23 EST

On 9/23/2016 10:40 AM, Peter Zijlstra wrote:
On Fri, Sep 23, 2016 at 10:15:46AM -0500, Babu Moger wrote:

Correct, We can't boot with lockdep. Sorry I did not make that clear.
We have a limit on static size of the kernel.
This stuff should be in .bss not .data. It should not affect the static
size at all. Or am I misunderstanding things?
Here it is.
$ ./scripts/bloat-o-meter vmlinux.lockdep.small vmlinux.lockdep.big
What does bloat-o-meter have to do with things? The static image size is
not dependent on .bss, right?

We checked again. Yes, It goes in .bss section. But in sparc we have to fit .text, .data,
.bss in 7 permanent TLBs(that is totally 28MB). It was fine so far. But the commit
1413c0389333 ("lockdep: Increase static allocations") added extra 4MB which makes
it go beyond 28MB. That is causing system boot up problems in sparc. Yes. We know it.
This is a limitation. Changing this limit in our hardware is a much bigger change which
we cannot address right away. So, we are trying to come up with a solution which can
work for all. I will re-post the patches with CONFIG_BASE_SMALL option if there is no

CCing David Miller and Rob Gardner. They might be able to explain more if you
have any more questions. Here is the discussion thread if you guys want to look at history.