On Tue, Jul 06, 2021 at 01:26:53PM -0700, 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 fix important enough for 4.14-rcx? I think so...
>
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -2785,10 +2785,32 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
> > * to fails, fallback to a single page allocator that is
> > * more permissive.
> > */
> > - if (!order)
> > - nr_allocated = alloc_pages_bulk_array_node(
> > - gfp, nid, nr_pages, pages);
> > - else
> > + if (!order) {
> > + while (nr_allocated < nr_pages) {
> > + int nr, nr_pages_request;
> > +
> > + /*
> > + * A maximum allowed request is hard-coded and is 100
> > + * pages per call. That is done in order to prevent a
> > + * long preemption off scenario in the bulk-allocator
> > + * so the range is [1:100].
> > + */
> > + nr_pages_request = min(100, (int)(nr_pages - nr_allocated));
>
> Yes, they types are all over the place.
>
> nr_pages: unsigned long
> nr_allocated: unsigned int
> nr, nr_pages_request: int
>
> Can we please choose the most appropriate type and use that
> consistently?
>
Let me think over it to see what i can do.
--
Vlad Rezki
