From: Paul Jackson Remove a couple of more lines of code from the cpuset hooks in the page allocation code path. There was a check for a NULL cpuset pointer in the routine cpuset_update_task_memory_state() that was only needed during system boot, after the memory subsystem was initialized, before the cpuset subsystem was initialized, to catch a NULL task->cpuset pointer. Add a cpuset_init_early() routine, just before the mem_init() call in init/main.c, that sets up just enough of the init tasks cpuset structure to render cpuset_update_task_memory_state() calls harmless. Signed-off-by: Paul Jackson Signed-off-by: Andrew Morton --- include/linux/cpuset.h | 2 ++ init/main.c | 1 + kernel/cpuset.c | 22 ++++++++++++++++------ 3 files changed, 19 insertions(+), 6 deletions(-) diff -puN include/linux/cpuset.h~cpuset-remove-test-for-null-cpuset-from-alloc-code-path include/linux/cpuset.h --- devel/include/linux/cpuset.h~cpuset-remove-test-for-null-cpuset-from-alloc-code-path 2005-12-14 02:47:40.000000000 -0800 +++ devel-akpm/include/linux/cpuset.h 2005-12-14 02:47:40.000000000 -0800 @@ -16,6 +16,7 @@ extern int number_of_cpusets; /* How many cpusets are defined in system? */ +extern int cpuset_init_early(void); extern int cpuset_init(void); extern void cpuset_init_smp(void); extern void cpuset_fork(struct task_struct *p); @@ -49,6 +50,7 @@ extern char *cpuset_task_status_allowed( #else /* !CONFIG_CPUSETS */ +static inline int cpuset_init_early(void) { return 0; } static inline int cpuset_init(void) { return 0; } static inline void cpuset_init_smp(void) {} static inline void cpuset_fork(struct task_struct *p) {} diff -puN init/main.c~cpuset-remove-test-for-null-cpuset-from-alloc-code-path init/main.c --- devel/init/main.c~cpuset-remove-test-for-null-cpuset-from-alloc-code-path 2005-12-14 02:47:40.000000000 -0800 +++ devel-akpm/init/main.c 2005-12-14 02:47:40.000000000 -0800 @@ -512,6 +512,7 @@ asmlinkage void __init start_kernel(void } #endif vfs_caches_init_early(); + cpuset_init_early(); mem_init(); kmem_cache_init(); setup_per_cpu_pageset(); diff -puN kernel/cpuset.c~cpuset-remove-test-for-null-cpuset-from-alloc-code-path kernel/cpuset.c --- devel/kernel/cpuset.c~cpuset-remove-test-for-null-cpuset-from-alloc-code-path 2005-12-14 02:47:40.000000000 -0800 +++ devel-akpm/kernel/cpuset.c 2005-12-14 02:48:05.000000000 -0800 @@ -603,9 +603,7 @@ static void guarantee_online_mems(const * Do not call this routine if in_interrupt(). * * Call without callback_sem or task_lock() held. May be called - * with or without manage_sem held. Except in early boot or - * an exiting task, when tsk->cpuset is NULL, this routine will - * acquire task_lock(). We don't need to use task_lock to guard + * with or without manage_sem held. Doesn't need task_lock to guard * against another task changing a non-NULL cpuset pointer to NULL, * as that is only done by a task on itself, and if the current task * is here, it is not simultaneously in the exit code NULL'ing its @@ -631,9 +629,6 @@ void cpuset_update_task_memory_state() struct task_struct *tsk = current; struct cpuset *cs = tsk->cpuset; - if (unlikely(!cs)) - return; - task_lock(tsk); my_cpusets_mem_gen = cs->mems_generation; task_unlock(tsk); @@ -1836,6 +1831,21 @@ static int cpuset_rmdir(struct inode *un return 0; } +/* + * cpuset_init_early - just enough so that the calls to + * cpuset_update_task_memory_state() in early init code + * are harmless. + */ + +int __init cpuset_init_early(void) +{ + struct task_struct *tsk = current; + + tsk->cpuset = &top_cpuset; + tsk->cpuset->mems_generation = atomic_read(&cpuset_mems_generation); + return 0; +} + /** * cpuset_init - initialize cpusets at system boot * _