diff options
| author |   Anton Vorontsov <anton.vorontsov@linaro.org> | 2012-05-31 16:26:26 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2012-05-31 17:49:30 -0700 |
| commit | 2c922c51e6924298f8271d75732964f1ffdecaf2 (patch) | |
| tree | 7ce86f8702cdf9ad93ad37064654fa21a43f411b /arch | |
| parent | um: fix possible race on task->mm (diff) | |
| download | linux-dev-2c922c51e6924298f8271d75732964f1ffdecaf2.tar.xz linux-dev-2c922c51e6924298f8271d75732964f1ffdecaf2.zip | |
um: properly check all process' threads for a live mm
kill_off_processes() might miss a valid process, this is because checking
for process->mm is not enough. Process' main thread may exit or detach
its mm via use_mm(), but other threads may still have a valid mm.
To catch this we use find_lock_task_mm(), which walks up all threads and
returns an appropriate task (with task lock held).
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/um/kernel/reboot.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/um/kernel/reboot.c b/arch/um/kernel/reboot.c index 1411f4e79f9a..3d15243ce692 100644 --- a/arch/um/kernel/reboot.c +++ b/arch/um/kernel/reboot.c @@ -6,6 +6,7 @@ #include "linux/sched.h" #include "linux/spinlock.h" #include "linux/slab.h" +#include "linux/oom.h" #include "kern_util.h" #include "os.h" #include "skas.h" @@ -25,13 +26,13 @@ static void kill_off_processes(void) read_lock(&tasklist_lock); for_each_process(p) { - task_lock(p); - if (!p->mm) { - task_unlock(p); + struct task_struct *t; + + t = find_lock_task_mm(p); + if (!t) continue; - } - pid = p->mm->context.id.u.pid; - task_unlock(p); + pid = t->mm->context.id.u.pid; + task_unlock(t); os_kill_ptraced_process(pid, 1); } read_unlock(&tasklist_lock); |