Re: strange allocation failures

[Michal Hocko <mhocko@kernel.org>]

On Mon 13-03-17 13:31:06, Andrey Ryabinin wrote:
> 
> 
> On 03/13/2017 01:10 PM, Dmitry Vyukov wrote:
> > On Mon, Mar 13, 2017 at 11:08 AM, Dmitry Vyukov <dvyukov@google.com> wrote:
> >> On Mon, Mar 13, 2017 at 11:04 AM, Andrey Ryabinin
> >> <aryabinin@virtuozzo.com> wrote:
> >>>
> >>>
> >>> On 03/13/2017 12:50 PM, Dmitry Vyukov wrote:
> >>>> Hello Andrey, Kirill,
> >>>>
> >>>> Can you please help me understand where is all my memory?
> >>>> I am running very moderate workload on a machine with 7.5GB of memory
> >>>> with KASAN. And I see constant vmalloc allocation failures for very
> >>>> moderate sizes. I am confused why it happens and where is all my
> >>>> memory...
> >>>>
> >>>
> >>>
> >>> Perhaps it's SIGKILL generated by syzkaller?
> >>>
> >>> static void *__vmalloc_area_node()
> >>> {
> >>> .....
> >>>                 if (fatal_signal_pending(current)) {
> >>>                         area->nr_pages = i;
> >>>                         goto fail;
> >>>                 }
> >>
> >>
> >> Ah, that would make sense. Syzkaller can indeed kill processes frequently.
> >>
> >> Perhaps we should not print the lengthy allocation failure message
> >> with all the details in such. Not sure how easy it is to filter out
> >> such cases.
> >> I have constant stream of these messages that just make everything
> >> else lost between them. And they are quite confusing. I've starred at
> >> the numbers trying to understand why I am short on memory.
> > 
> > 
> > Seems trivial. What do you think of:
> > 
> 
> Makes sense. ACK.
 
yes, looks reasonably to me as well. I will ack the patch with the full
changelog. Please CC me.

> 
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index 0dd80222b20b..0b057628a7ba 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -1683,7 +1683,7 @@ static void *__vmalloc_area_node(struct
> > vm_struct *area, gfp_t gfp_mask,
> > 
> >                 if (fatal_signal_pending(current)) {
> >                         area->nr_pages = i;
> > -                       goto fail;
> > +                       goto fail_no_warn;
> >                 }
> > 
> >                 if (node == NUMA_NO_NODE)
> > @@ -1709,6 +1709,7 @@ static void *__vmalloc_area_node(struct
> > vm_struct *area, gfp_t gfp_mask,
> >         warn_alloc(gfp_mask, NULL,
> >                           "vmalloc: allocation failure, allocated %ld
> > of %ld bytes",
> >                           (area->nr_pages*PAGE_SIZE), area->size);
> > +fail_no_warn:
> >         vfree(area->addr);
> >         return NULL;
> >  }
> > 
> > 
> > ?
> > 
> 
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-- 
Michal Hocko
SUSE Labs

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