Commit c417f024 authored by Paul Jackson's avatar Paul Jackson Committed by Linus Torvalds
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[PATCH] cpuset: remove test for null cpuset from alloc code path 



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: default avatarPaul Jackson <pj@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 04c19fa6

include/linux/cpuset.h

+2 −0
Original line number Diff line number Diff line
@@ -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(struct task_struct *task, char *buffer); 


#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) {}

init/main.c

+1 −0
Original line number Diff line number Diff line
@@ -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();

kernel/cpuset.c

+16 −6
Original line number Diff line number Diff line
@@ -603,9 +603,7 @@ static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask) 
 * 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 *unused_dir, struct dentry *dentry) 
	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

 *

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