On Wed 27-06-18 14:44:47, Cannon Matthews wrote: > When booting with very large numbers of gigantic (i.e. 1G) pages, the > operations in the loop of gather_bootmem_prealloc, and specifically > prep_compound_gigantic_page, takes a very long time, and can cause a > softlockup if enough pages are requested at boot. > > For example booting with 3844 1G pages requires prepping > (set_compound_head, init the count) over 1 billion 4K tail pages, which > takes considerable time. This should also apply to reserving the same > amount of memory as 2M pages, as the same number of struct pages > are affected in either case. > > Add a cond_resched() to the outer loop in gather_bootmem_prealloc() to > prevent this lockup. > > Tested: Booted with softlockup_panic=1 hugepagesz=1G hugepages=3844 and > no softlockup is reported, and the hugepages are reported as > successfully setup. > > Signed-off-by: Cannon Matthews <cannonmatthews@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Thanks! > --- > mm/hugetlb.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index a963f2034dfc..d38273c32d3b 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -2169,6 +2169,7 @@ static void __init gather_bootmem_prealloc(void) > */ > if (hstate_is_gigantic(h)) > adjust_managed_page_count(page, 1 << h->order); > + cond_resched(); > } > } > > -- > 2.18.0.rc2.346.g013aa6912e-goog -- Michal Hocko SUSE Labs
