Commit e56d090310d7625ecb43a1eeebd479f04affb48b [PATCH] RCU signal handling made this BUG_ON() unsafe. This code runs under ->siglock, while switch_exec_pids() takes tasklist_lock. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Linus Torvalds <torvalds@osdl.org>