On 11/13, 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. I am fine with this patch as well, but honestly I'd prefer the previous v5. I won't argue though. > +/* > + * Careful: while_each_thread is not RCU safe. Callers should hold > + * read_lock(tasklist_lock) across while_each_thread loops. > + */ (tasklist_lock or siglock, in fact but this doesn't matter). This is not that simple, even tasklist_lock can't help if the task is already dead. Oh. Yes, sorry. I promised to send the patches "soon" many times, but still didn't find the time. Perhaps I should try to start with the "make this all less buggy" changes, the "complete" fix needs to change the callers as well. Oleg. -- 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>