-stable review patch. If anyone has any objections, please let us know. ------------------ From: Oleg Nesterov 1. fill_tgid() forgets to do put_task_struct(first). 2. release_task(first) can happen after fill_tgid() drops tasklist_lock, it is unsafe to dereference first->signal. This is a temporary fix, imho the locking should be reworked. Signed-off-by: Oleg Nesterov Cc: Shailabh Nagar Cc: Balbir Singh Cc: Jay Lan Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Chris Wright --- kernel/taskstats.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) --- linux-2.6.18.1.orig/kernel/taskstats.c +++ linux-2.6.18.1/kernel/taskstats.c @@ -229,14 +229,17 @@ static int fill_tgid(pid_t tgid, struct } else get_task_struct(first); - /* Start with stats from dead tasks */ - spin_lock_irqsave(&first->signal->stats_lock, flags); - if (first->signal->stats) - memcpy(stats, first->signal->stats, sizeof(*stats)); - spin_unlock_irqrestore(&first->signal->stats_lock, flags); tsk = first; read_lock(&tasklist_lock); + /* Start with stats from dead tasks */ + if (first->signal) { + spin_lock_irqsave(&first->signal->stats_lock, flags); + if (first->signal->stats) + memcpy(stats, first->signal->stats, sizeof(*stats)); + spin_unlock_irqrestore(&first->signal->stats_lock, flags); + } + do { if (tsk->exit_state == EXIT_ZOMBIE && thread_group_leader(tsk)) continue; @@ -256,7 +259,7 @@ static int fill_tgid(pid_t tgid, struct * Accounting subsytems can also add calls here to modify * fields of taskstats. */ - + put_task_struct(first); return 0; } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/