Re: 2.6.8-rc3-mm1

[William Lee Irwin III <wli@holomorphy.com>]

On Thu, Aug 05, 2004 at 03:19:18AM -0700, Andrew Morton wrote:
> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.8-rc3/2.6.8-rc3-mm1/
> - Added David Woodhouse's MTD tree to the "external trees" list
> - Dropped the staircase scheduler, mainly because the schedstats patch broke
>   it.
>   We learned quite a lot from having staircase in there.  Now it's time for
>   a new scheduler anyway.

On some arches, e.g. ia64, it appears that timer ticks can be taken
very, very early. In order to avoid oopsing on a prof_buffer that
hasn't yet been bootmem allocated, check prof_buffer in profile_hit().


--- mm1-2.6.8-rc3/kernel/profile.c.orig	2004-08-06 01:24:10.000000000 -0700
+++ mm1-2.6.8-rc3/kernel/profile.c	2004-08-06 01:49:55.000000000 -0700
@@ -171,7 +171,7 @@
 {
 	unsigned long pc;
 
-	if (prof_on != type)
+	if (prof_on != type || !prof_buffer)
 		return;
 	pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
 	atomic_inc(&prof_buffer[min(pc, prof_len - 1)]);