3.16.39-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Jia He <[email protected]> commit 649920c6ab93429b94bc7c1aa7c0e8395351be32 upstream. In powerpc servers with large memory(32TB), we watched several soft lockups for hugepage under stress tests. The call traces are as follows: 1. get_page_from_freelist+0x2d8/0xd50 __alloc_pages_nodemask+0x180/0xc20 alloc_fresh_huge_page+0xb0/0x190 set_max_huge_pages+0x164/0x3b0 2. prep_new_huge_page+0x5c/0x100 alloc_fresh_huge_page+0xc8/0x190 set_max_huge_pages+0x164/0x3b0 This patch fixes such soft lockups. It is safe to call cond_resched() there because it is out of spin_lock/unlock section. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Jia He <[email protected]> Reviewed-by: Naoya Horiguchi <[email protected]> Acked-by: Michal Hocko <[email protected]> Acked-by: Dave Hansen <[email protected]> Cc: Mike Kravetz <[email protected]> Cc: "Kirill A. Shutemov" <[email protected]> Cc: Paul Gortmaker <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> --- mm/hugetlb.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1655,6 +1655,10 @@ static unsigned long set_max_huge_pages( * and reducing the surplus. */ spin_unlock(&hugetlb_lock); + + /* yield cpu to avoid soft lockup */ + cond_resched(); + if (hstate_is_gigantic(h)) ret = alloc_fresh_gigantic_page(h, nodes_allowed); else
