On Thu, Oct 05, 2017 at 06:42:38AM +0900, Tetsuo Handa wrote: > Johannes Weiner wrote: > > On Thu, Oct 05, 2017 at 05:49:43AM +0900, Tetsuo Handa wrote: > > > On 2017/10/05 3:59, Johannes Weiner wrote: > > > > But the justification to make that vmalloc() call fail like this isn't > > > > convincing, either. The patch mentions an OOM victim exhausting the > > > > memory reserves and thus deadlocking the machine. But the OOM killer > > > > is only one, improbable source of fatal signals. It doesn't make sense > > > > to fail allocations preemptively with plenty of memory in most cases. > > > > > > By the time the current thread reaches do_exit(), > > > fatal_signal_pending(current) > > > should become false. As far as I can guess, the source of fatal signal > > > will be > > > tty_signal_session_leader(tty, exit_session) which is called just before > > > tty_ldisc_hangup(tty, cons_filp != NULL) rather than the OOM killer. I > > > don't > > > know whether it is possible to make fatal_signal_pending(current) true > > > inside > > > do_exit() though... > > > > It's definitely not the OOM killer, the memory situation looks fine > > when this happens. I didn't look closer where the signal comes from. > > > > Then, we could check tsk_is_oom_victim() instead of fatal_signal_pending().
The case for this patch didn't seem very strong to beging with, and since it's causing problems a simple revert makes more sense than an attempt to fine-tune it. Generally, we should leave it to the page allocator to handle memory reserves, not annotate random alloc_page() callsites.
