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 <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 04c19fa6
......@@ -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) {}
......@@ -512,6 +512,7 @@ asmlinkage void __init start_kernel(void)
......@@ -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))
my_cpusets_mem_gen = cs->mems_generation;
......@@ -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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