Re: [PATCH V2] mm/hugetlb: Avoid soft lockup in set_max_huge_pages()
From: Naoya Horiguchi <hidden>
Date: 2016-07-28 06:43:58
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On Thu, Jul 28, 2016 at 10:54:02AM +0800, Jia He wrote:
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 <redacted> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Naoya Horiguchi <redacted> Cc: Mike Kravetz <redacted> Cc: "Kirill A. Shutemov" <redacted> Cc: Michal Hocko <mhocko@suse.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Paul Gortmaker <redacted>
Looks good to me. Reviewed-by: Naoya Horiguchi <redacted> Thanks, Naoya Horiguchi
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--- 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
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