On Wed, 3 Dec 2014, Oleg Nesterov wrote: > oom_kill.c assumes that PF_EXITING task should exit and free the memory > soon. This is wrong in many ways and one important case is the coredump. > A task can sleep in exit_mm() "forever" while the coredumping sub-thread > can need more memory. > > Change the PF_EXITING checks to take SIGNAL_GROUP_COREDUMP into account, > we add the new trivial helper for that. > > Note: this is only the first step, this patch doesn't try to solve other > problems. The SIGNAL_GROUP_COREDUMP check is obviously racy, a task can > participate in coredump after it was already observed in PF_EXITING state, > so TIF_MEMDIE (which also blocks oom-killer) still can be wrongly set. > fatal_signal_pending() can be true because of SIGNAL_GROUP_COREDUMP so > out_of_memory() and mem_cgroup_out_of_memory() shouldn't blindly trust it. > And even the name/usage of the new helper is confusing, an exiting thread > can only free its ->mm if it is the only/last task in thread group. > > Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: David Rientjes <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
