On Thu 06-09-18 19:58:25, Tetsuo Handa wrote: [...] > >From 18876f287dd69a7c33f65c91cfcda3564233f55e Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Date: Thu, 6 Sep 2018 19:53:18 +0900 > Subject: [PATCH] mm, oom: Introduce time limit for dump_tasks duration. > > Since printk() is slow, printing one line takes nearly 0.01 second. > As a result, syzbot is stalling for 52 seconds trying to dump 5600 > tasks at for_each_process() under RCU. Since such situation is almost > inflight fork bomb attack (the OOM killer will print similar tasks for > so many times), it makes little sense to print all candidate tasks. > Thus, this patch introduces 3 seconds limit for printing. > > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> You really love timeout based solutions with randomly chosen timeouts, don't you. This is just ugly as hell. We already have means to disable tasks dumping (see /proc/sys/vm/oom_dump_tasks). -- Michal Hocko SUSE Labs
