Commit 31950eb6 authored by Linus Torvalds's avatar Linus Torvalds

mm/init: cpu_hotplug_init() must be initialized before SLAB

SLAB uses get/put_online_cpus() which use a mutex which is itself only
initialized when cpu_hotplug_init() is called.  Currently we hang suring
boot in SLAB due to doing that too late.

Reported by James Bottomley and Sachin Sant (and possibly others).
Debugged by Benjamin Herrenschmidt.

This just removes the dynamic initialization of the data structures, and
replaces it with a static one, avoiding this dependency entirely, and
removing one unnecessary special initcall.
Tested-by: default avatarSachin Sant <sachinp@in.ibm.com>
Tested-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
Tested-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ac1b7c37
...@@ -69,7 +69,6 @@ static inline void unregister_cpu_notifier(struct notifier_block *nb) ...@@ -69,7 +69,6 @@ static inline void unregister_cpu_notifier(struct notifier_block *nb)
int cpu_up(unsigned int cpu); int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu); void notify_cpu_starting(unsigned int cpu);
extern void cpu_hotplug_init(void);
extern void cpu_maps_update_begin(void); extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void); extern void cpu_maps_update_done(void);
...@@ -84,10 +83,6 @@ static inline void unregister_cpu_notifier(struct notifier_block *nb) ...@@ -84,10 +83,6 @@ static inline void unregister_cpu_notifier(struct notifier_block *nb)
{ {
} }
static inline void cpu_hotplug_init(void)
{
}
static inline void cpu_maps_update_begin(void) static inline void cpu_maps_update_begin(void)
{ {
} }
......
...@@ -678,7 +678,6 @@ asmlinkage void __init start_kernel(void) ...@@ -678,7 +678,6 @@ asmlinkage void __init start_kernel(void)
#endif #endif
page_cgroup_init(); page_cgroup_init();
enable_debug_pagealloc(); enable_debug_pagealloc();
cpu_hotplug_init();
kmemtrace_init(); kmemtrace_init();
kmemleak_init(); kmemleak_init();
debug_objects_mem_init(); debug_objects_mem_init();
......
...@@ -34,14 +34,11 @@ static struct { ...@@ -34,14 +34,11 @@ static struct {
* an ongoing cpu hotplug operation. * an ongoing cpu hotplug operation.
*/ */
int refcount; int refcount;
} cpu_hotplug; } cpu_hotplug = {
.active_writer = NULL,
void __init cpu_hotplug_init(void) .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
{ .refcount = 0,
cpu_hotplug.active_writer = NULL; };
mutex_init(&cpu_hotplug.lock);
cpu_hotplug.refcount = 0;
}
#ifdef CONFIG_HOTPLUG_CPU #ifdef CONFIG_HOTPLUG_CPU
......
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