diff options
| author | Anton Vorontsov <anton.vorontsov@linaro.org> | 2012-05-31 16:26:23 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-05-31 17:49:29 -0700 |
| commit | 73863ab028579ed98c4f1f36d016536b1b415344 (patch) | |
| tree | 8ad66593e4b2ebd7f32acdb2e53dc0bb8dd201f5 /arch/powerpc | |
| parent | 3eaa73bde2fb475b731a0fde7dd11c3ecfb8679c (diff) | |
powerpc: use clear_tasks_mm_cpumask()
Current CPU hotplug code has some task->mm handling issues:
1. Working with task->mm w/o getting mm or grabing the task lock is
dangerous as ->mm might disappear (exit_mm() assigns NULL under
task_lock(), so tasklist lock is not enough).
We can't use get_task_mm()/mmput() pair as mmput() might sleep,
so we must take the task lock while handle its mm.
2. Checking for process->mm is not enough because process' main
thread may exit or detach its mm via use_mm(), but other threads
may still have a valid mm.
To fix this we would need to use find_lock_task_mm(), which would
walk up all threads and returns an appropriate task (with task
lock held).
clear_tasks_mm_cpumask() has all the issues fixed, so let's use it.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/mm/mmu_context_nohash.c | 11 |
1 files changed, 2 insertions, 9 deletions
diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c index 5b63bd3da4a..e779642c25e 100644 --- a/arch/powerpc/mm/mmu_context_nohash.c +++ b/arch/powerpc/mm/mmu_context_nohash.c @@ -333,9 +333,7 @@ static int __cpuinit mmu_context_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { unsigned int cpu = (unsigned int)(long)hcpu; -#ifdef CONFIG_HOTPLUG_CPU - struct task_struct *p; -#endif + /* We don't touch CPU 0 map, it's allocated at aboot and kept * around forever */ @@ -358,12 +356,7 @@ static int __cpuinit mmu_context_cpu_notify(struct notifier_block *self, stale_map[cpu] = NULL; /* We also clear the cpu_vm_mask bits of CPUs going away */ - read_lock(&tasklist_lock); - for_each_process(p) { - if (p->mm) - cpumask_clear_cpu(cpu, mm_cpumask(p->mm)); - } - read_unlock(&tasklist_lock); + clear_tasks_mm_cpumask(cpu); break; #endif /* CONFIG_HOTPLUG_CPU */ } |