Messages in this thread Patch in this message | | | From | Rusty Russell <> | Subject | Re: [PULL] x86 cpumask work | Date | Sun, 15 Mar 2009 13:26:33 +1030 |
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On Saturday 14 March 2009 01:57:42 Ingo Molnar wrote: > Note, it might have crashed in a cpu hotplug test i'm conducting > during bootup: > > echo 0 > /sys/devices/system/cpu/cpu1/online
Indeed, thanks!
Subject: cpumask: fix crash when offlining cpus
Impact: Fix cpu offline when CONFIG_MAXSMP=y
Changeset bc9b83dd1f66402b870301c3c7117b9c1484abb4 "cpumask: convert c1e_mask in arch/x86/kernel/process.c to cpumask_var_t" contained a bug: c1e_mask is manipulated even if C1E isn't detected (and hence not allocated). This is simply fixed by checking for NULL (which gcc optimizes out anyway of CONFIG_CPUMASK_OFFSTACK=n, since it knows ce1_mask can never be NULL).
In addition, fix a leak where select_idle_routine re-allocates (and re-clears) c1e_mask on every cpu init.
Reported-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index cad5431..91a8c26 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -479,7 +479,8 @@ static int c1e_detected; void c1e_remove_cpu(int cpu) { - cpumask_clear_cpu(cpu, c1e_mask); + if (c1e_mask != NULL) + cpumask_clear_cpu(cpu, c1e_mask); } /* @@ -556,8 +557,11 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) pm_idle = mwait_idle; } else if (check_c1e_idle(c)) { printk(KERN_INFO "using C1E aware idle routine\n"); - alloc_cpumask_var(&c1e_mask, GFP_KERNEL); - cpumask_clear(c1e_mask); + /* c1e_mask can only be NULL during boot of first cpu. */ + if (c1e_mask == NULL) { + alloc_cpumask_var(&c1e_mask, GFP_KERNEL); + cpumask_clear(c1e_mask); + } pm_idle = c1e_idle; } else pm_idle = default_idle;
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