On Wed, Jul 07, 2021 at 10:42:29AM +0200, Michal Hocko wrote: > On Tue 06-07-21 13:26:53, Andrew Morton wrote: > > On Mon, 5 Jul 2021 19:05:36 +0200 "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx> wrote: > > > > > In case of simultaneous vmalloc allocations, for example it is 1GB and > > > 12 CPUs my system is able to hit "BUG: soft lockup" for !CONFIG_PREEMPT > > > kernel. > > > > > > <snip> > > > ... > > > > > > are obtained, i.e. do batched page requests adding cond_resched() meanwhile > > > to reschedule. Batched value is hard-coded and is 100 pages per call. > > > > > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> > > > > Can we please have a Fixes: for this? > > Is this a fix for any actual real life problem? I mean allocating 1GB of > vmalloc space back and forth sounds like a stretch to me. > It is not a real scenario. I simulated it by the stress-suite tests. So the Fixes tag is not needed, IMHO. > > Is this fix important enough for 4.14-rcx? I think so... > > I do not think so. This is an improvement so that vmalloc behaves more > sanely for those abusers... > A bulk-allocator has recently been introduced, so 4.x does not have it, i.e. this change is not applicable and 4.x kernel does not suffer from it. -- Vlad Rezki
