[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: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index cf8203a..fc949e4 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -603,9 +603,7 @@
* 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 @@
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 @@
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
*