On Tue, Nov 12, 2013 at 12:01 PM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > On 11/11, Sameer Nanda wrote: >> >> The selection of the process to be killed happens in two spots: >> first in select_bad_process and then a further refinement by >> looking for child processes in oom_kill_process. Since this is >> a two step process, it is possible that the process selected by >> select_bad_process may get a SIGKILL just before oom_kill_process >> executes. If this were to happen, __unhash_process deletes this >> process from the thread_group list. This results in oom_kill_process >> getting stuck in an infinite loop when traversing the thread_group >> list of the selected process. >> >> Fix this race by adding a pid_alive check for the selected process >> with tasklist_lock held in oom_kill_process. > > OK, looks correct to me. Thanks. > > > Yes, this is a step backwards, hopefully we will revert this patch soon. > I am starting to think something like while_each_thread_lame_but_safe() > makes sense before we really fix this nasty (and afaics not simple) > problem with with while_each_thread() (which should die). Looking forward to a real fix for the nasty problems with while_each_thread. In the meanwhile, let me float one more (hopefully, the last) version of this patch that should address Michal's concern. Thanks for your feedback! > > Oleg. > -- Sameer -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>