From: Oleg Nesterov <[email protected]> Subject: vm_is_stack: use for_each_thread() rather then buggy while_each_thread()
Aleksei hit the soft lockup during reading /proc/PID/smaps. David investigated the problem and suggested the right fix. while_each_thread() is racy and should die, this patch updates vm_is_stack(). Signed-off-by: Oleg Nesterov <[email protected]> Reported-by: Aleksei Besogonov <[email protected]> Tested-by: Aleksei Besogonov <[email protected]> Suggested-by: David Rientjes <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- mm/util.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff -puN mm/util.c~vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread mm/util.c --- a/mm/util.c~vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread +++ a/mm/util.c @@ -183,17 +183,14 @@ pid_t vm_is_stack(struct task_struct *ta if (in_group) { struct task_struct *t; - rcu_read_lock(); - if (!pid_alive(task)) - goto done; - t = task; - do { + rcu_read_lock(); + for_each_thread(task, t) { if (vm_is_stack_for_task(t, vma)) { ret = t->pid; goto done; } - } while_each_thread(task, t); + } done: rcu_read_unlock(); } _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
