| From 520495fe96d74e05db585fc748351e0504d8f40d Mon Sep 17 00:00:00 2001 |
| From: Cannon Matthews <cannonmatthews@google.com> |
| Date: Tue, 3 Jul 2018 17:02:43 -0700 |
| Subject: mm: hugetlb: yield when prepping struct pages |
| |
| From: Cannon Matthews <cannonmatthews@google.com> |
| |
| commit 520495fe96d74e05db585fc748351e0504d8f40d upstream. |
| |
| 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. |
| |
| 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. |
| |
| Link: http://lkml.kernel.org/r/20180627214447.260804-1-cannonmatthews@google.com |
| Signed-off-by: Cannon Matthews <cannonmatthews@google.com> |
| Reviewed-by: Andrew Morton <akpm@linux-foundation.org> |
| Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> |
| Acked-by: Michal Hocko <mhocko@suse.com> |
| Cc: Andres Lagar-Cavilla <andreslc@google.com> |
| Cc: Peter Feiner <pfeiner@google.com> |
| Cc: Greg Thelen <gthelen@google.com> |
| Cc: <stable@vger.kernel.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/hugetlb.c | 1 + |
| 1 file changed, 1 insertion(+) |
| |
| --- a/mm/hugetlb.c |
| +++ b/mm/hugetlb.c |
| @@ -2038,6 +2038,7 @@ static void __init gather_bootmem_preall |
| */ |
| if (hstate_is_gigantic(h)) |
| adjust_managed_page_count(page, 1 << h->order); |
| + cond_resched(); |
| } |
| } |
| |