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Date: Wed, 18 Mar 2009 08:51:35 GMT
From: Rusty Russell <rusty@...tcorp.com.au>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
travis@....com, rusty@...tcorp.com.au, tglx@...utronix.de,
mingo@...e.hu
Subject: [tip:cpus4096] cpumask: fix CONFIG_CPUMASK_OFFSTACK=y cpu hotunplug crash
Commit-ID: 30e1e6d1af2b67558bccf322af2b3e0676b209ae
Gitweb: http://git.kernel.org/tip/30e1e6d1af2b67558bccf322af2b3e0676b209ae
Author: Rusty Russell <rusty@...tcorp.com.au>
AuthorDate: Tue, 17 Mar 2009 14:50:34 +1030
Commit: Ingo Molnar <mingo@...e.hu>
CommitDate: Wed, 18 Mar 2009 09:40:35 +0100
cpumask: fix CONFIG_CPUMASK_OFFSTACK=y cpu hotunplug crash
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@...e.hu>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Cc: Mike Travis <travis@....com>
LKML-Reference: <200903171450.34549.rusty@...tcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
arch/x86/include/asm/processor.h | 1 +
arch/x86/kernel/cpu/common.c | 1 +
arch/x86/kernel/process.c | 14 +++++++++++---
3 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index d794d94..9874dd9 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -733,6 +733,7 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
extern void select_idle_routine(const struct cpuinfo_x86 *c);
+extern void init_c1e_mask(void);
extern unsigned long boot_option_idle_override;
extern unsigned long idle_halt;
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 82f6cc0..d7dd3c2 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -812,6 +812,7 @@ static void vgetcpu_set_mode(void)
void __init identify_boot_cpu(void)
{
identify_cpu(&boot_cpu_data);
+ init_c1e_mask();
#ifdef CONFIG_X86_32
sysenter_setup();
enable_sep_cpu();
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 6638294..78533a5 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);
}
/*
@@ -556,13 +557,20 @@ 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);
pm_idle = c1e_idle;
} else
pm_idle = default_idle;
}
+void __init init_c1e_mask(void)
+{
+ /* If we're using c1e_idle, we need to allocate c1e_mask. */
+ if (pm_idle == c1e_idle) {
+ alloc_cpumask_var(&c1e_mask, GFP_KERNEL);
+ cpumask_clear(c1e_mask);
+ }
+}
+
static int __init idle_setup(char *str)
{
if (!str)
--
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