In powerpc servers with large memory(32TB), we watched several soft
lockups for hugepage under stress tests.
The call trace 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 is to fix such soft lockups. It is safe to call cond_resched()
there because it is out of spin_lock/unlock section.
Signed-off-by: Jia He <hejia...@gmail.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
Cc: Mike Kravetz <mike.krav...@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shute...@linux.intel.com>
Cc: Michal Hocko <mho...@suse.com>
Cc: Dave Hansen <dave.han...@linux.intel.com>
Cc: Paul Gortmaker <paul.gortma...@windriver.com>
---
Changes in V2: move cond_resched to a common calling site in set_max_huge_pages
mm/hugetlb.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index abc1c5f..9284280 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2216,6 +2216,10 @@ static unsigned long set_max_huge_pages(struct hstate
*h, unsigned long count,
* 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
--
2.5.0
