On Sun, Oct 31, 2010 at 08:33:35AM +0900, Tetsuo Handa wrote: > Paul E. McKenney wrote: > > So we should remove the lockdep_tasklist_lock_is_held() and then > > apply Sergey's patch, correct? > > Yes. rcu_lockdep_assert(rcu_read_lock_held()) in find_task_by_pid_ns() > is correct and callers need to use rcu_read_lock(). > > As of 2.6.32, there are 20+ users who missed rcu_read_lock(). > So, similar reports will be posted like popcorn. > http://kerneltrap.org/mailarchive/linux-kernel/2009/12/11/4518016 OK, let's see how these are in 2.6.36... The summary is that almost all of the popcorn kernels have already popped. > Users missing read_lock(&tasklist_lock) when calling find_task_by_vpid(): > > get_net_ns_by_pid() in net/core/net_namespace.c Fixed with rcu_read_lock(). > seq_print_userip_objs() in kernel/trace/trace_output.c Fixed with rcu_read_lock(). > fill_pid() in kernel/taskstats.c This one seems to be named fill_stats_for_pid(), and it is fixed with rcu_read_lock(). > fill_tgid() in kernel/taskstats.c This one seems to be named fill_stats_for_tgid(), and it is fixed with rcu_read_lock(). > futex_find_get_task() in kernel/futex.c Fixed with rcu_read_lock(). > SYSCALL_DEFINE3(get_robust_list) in kernel/futex.c Fixed with rcu_read_lock(). > compat_sys_get_robust_list() in kernel/futex_compat.c Fixed with rcu_read_lock(). > ptrace_get_task_struct() in kernel/ptrace.c Fixed with rcu_read_lock(). > do_send_specific() in kernel/signal.c Fixed with rcu_read_lock(). > find_get_context() in kernel/perf_event.c Fixed with rcu_read_lock() plus code motion. > posix_cpu_clock_get() in kernel/posix-cpu-timers.c Fixed with rcu_read_lock(). > good_sigevent() in kernel/posix-timers.c Fixed with rcu_read_lock() in caller. > attach_task_by_pid() in kernel/cgroup.c Fixed with rcu_read_lock(). > SYSCALL_DEFINE1(getpgid) in kernel/sys.c Fixed with rcu_read_lock(). > SYSCALL_DEFINE1(getsid) in kernel/sys.c Fixed with rcu_read_lock(). > do_sched_setscheduler() in kernel/sched.c Fixed with rcu_read_lock(). > > Users missing rcu_read_lock() when calling find_task_by_vpid(): > > SYSCALL_DEFINE3(ioprio_set) in fs/ioprio.c Patches in flight. > SYSCALL_DEFINE2(ioprio_get) in fs/ioprio.c Patches in flight. > cap_get_target_pid() in kernel/capability.c Fixed with rcu_read_lock(). > audit_prepare_user_tty() in kernel/audit.c Fixed with rcu_read_lock(). > audit_receive_msg() in kernel/audit.c Fixed with rcu_read_lock(), two instances. > check_clock() in kernel/posix-cpu-timers.c This one has read_lock(&tasklist_lock). > posix_cpu_timer_create() in kernel/posix-cpu-timers.c This one has read_lock(&tasklist_lock). > SYSCALL_DEFINE3(setpriority) in kernel/sys.c This one has both read_lock(&tasklist_lock) and rcu_read_lock(). Both belt -and- suspenders... > SYSCALL_DEFINE2(getpriority) in kernel/sys.c Ditto. > SYSCALL_DEFINE2(setpgid) in kernel/sys.c This one has both write_lock_irq(&tasklist_lock) and rcu_read_lock(). -Serious- belt along with the suspenders... > SYSCALL_DEFINE1(sched_getscheduler) in kernel/sched.c Fixed with rcu_read_lock(). > SYSCALL_DEFINE2(sched_getparam) in kernel/sched.c Fixed with rcu_read_lock(). > sched_setaffinity() in kernel/sched.c Fixed with rcu_read_lock(). > sched_getaffinity() in kernel/sched.c Fixed with rcu_read_lock(). > SYSCALL_DEFINE2(sched_rr_get_interval) in kernel/sched.c Fixed with rcu_read_lock(). > tomoyo_is_select_one() in security/tomoyo/common.c This one has both read_lock(&tasklist_lock) and rcu_read_lock(). Both belt -and- suspenders... (Also renamed to tomoyo_select_one().) > tomoyo_read_pid() in security/tomoyo/common.c This one has both read_lock(&tasklist_lock) and rcu_read_lock(). Both belt -and- suspenders... > SYSCALL_DEFINE6(move_pages) in mm/migrate.c This one does read_lock(&tasklist_lock). > SYSCALL_DEFINE4(migrate_pages) in mm/mempolicy.c No call to find_task_by_vpid() in migrate_pages() anymore, but there is one protected by read_lock(&tasklist_lock) in move_pages(). > find_process_by_pid() in arch/mips/kernel/mips-mt-fpaff.c No change, so let's check the callers: mipsmt_sys_sched_setaffinity(): rcu_read_lock(). mipsmt_sys_sched_getaffinity(): read_lock(&tasklist_lock). do_sched_setscheduler(): rcu_read_lock(). sched_getscheduler(): rcu_read_lock(). sched_getparam(): rcu_read_lock(). sched_setaffinity(): rcu_read_lock(). sched_getaffinity(); rcu_read_lock(). sched_rr_get_interval(): rcu_read_lock(). So all of these are protected. > pfm_get_task() in arch/ia64/kernel/perfmon.c This one does read_lock(&tasklist_lock). > cxn_pin_by_pid() in arch/frv/mm/mmu-context.c This one does read_lock(&tasklist_lock). > > Users missing read_lock(&tasklist_lock) when calling find_task_by_pid_ns(): > > rest_init() in init/main.c Fixed with rcu_read_lock(). > proc_pid_lookup() in fs/proc/base.c Fixed with rcu_read_lock(). > proc_task_lookup() in fs/proc/base.c Fixed with rcu_read_lock(). > first_tid() in fs/proc/base.c Fixed with rcu_read_lock(). > getthread() in kernel/kgdb.c This is now in kernel/debug/gdbstub.c... It looks to need an rcu_read_lock(). It has a comment, but... > mconsole_stack() in arch/um/drivers/mconsole_kern.c This one still needs help. > > Users missing rcu_read_lock() when calling find_task_by_pid_ns(): > > rest_init() in init/main.c Fixed with rcu_read_lock(). > getthread() in kernel/kgdb.c This one still needs help. > mconsole_stack() in arch/um/drivers/mconsole_kern.c This one still needs help. So mostly there... Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
