From: Oleg Nesterov lock_task_sighand() can take ->siglock without holding tasklist_lock. Signed-off-by: Oleg Nesterov Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton --- fs/proc/array.c | 11 +++++------ 1 files changed, 5 insertions(+), 6 deletions(-) diff -puN fs/proc/array.c~proc-convert-task_sig-to-use-lock_task_sighand fs/proc/array.c --- a/fs/proc/array.c~proc-convert-task_sig-to-use-lock_task_sighand +++ a/fs/proc/array.c @@ -244,6 +244,7 @@ static void collect_sigign_sigcatch(stru static inline char * task_sig(struct task_struct *p, char *buffer) { + unsigned long flags; sigset_t pending, shpending, blocked, ignored, caught; int num_threads = 0; unsigned long qsize = 0; @@ -255,10 +256,8 @@ static inline char * task_sig(struct tas sigemptyset(&ignored); sigemptyset(&caught); - /* Gather all the data with the appropriate locks held */ - read_lock(&tasklist_lock); - if (p->sighand) { - spin_lock_irq(&p->sighand->siglock); + rcu_read_lock(); + if (lock_task_sighand(p, &flags)) { pending = p->pending.signal; shpending = p->signal->shared_pending.signal; blocked = p->blocked; @@ -266,9 +265,9 @@ static inline char * task_sig(struct tas num_threads = atomic_read(&p->signal->count); qsize = atomic_read(&p->user->sigpending); qlim = p->signal->rlim[RLIMIT_SIGPENDING].rlim_cur; - spin_unlock_irq(&p->sighand->siglock); + unlock_task_sighand(p, &flags); } - read_unlock(&tasklist_lock); + rcu_read_unlock(); buffer += sprintf(buffer, "Threads:\t%d\n", num_threads); buffer += sprintf(buffer, "SigQ:\t%lu/%lu\n", qsize, qlim); _