On Sat 04-05-19 20:28:24, Zhiqiang Liu wrote:
> From: Kai Shen <shenkai8@xxxxxxxxxx>
>
> spinlock recursion happened when do LTP test:
> #!/bin/bash
> ./runltp -p -f hugetlb &
> ./runltp -p -f hugetlb &
> ./runltp -p -f hugetlb &
> ./runltp -p -f hugetlb &
> ./runltp -p -f hugetlb &
>
> The dtor returned by get_compound_page_dtor in __put_compound_page
> may be the function of free_huge_page which will lock the hugetlb_lock,
> so don't put_page in lock of hugetlb_lock.
>
> BUG: spinlock recursion on CPU#0, hugemmap05/1079
> lock: hugetlb_lock+0x0/0x18, .magic: dead4ead, .owner: hugemmap05/1079, .owner_cpu: 0
> Call trace:
> dump_backtrace+0x0/0x198
> show_stack+0x24/0x30
> dump_stack+0xa4/0xcc
> spin_dump+0x84/0xa8
> do_raw_spin_lock+0xd0/0x108
> _raw_spin_lock+0x20/0x30
> free_huge_page+0x9c/0x260
> __put_compound_page+0x44/0x50
> __put_page+0x2c/0x60
> alloc_surplus_huge_page.constprop.19+0xf0/0x140
> hugetlb_acct_memory+0x104/0x378
> hugetlb_reserve_pages+0xe0/0x250
> hugetlbfs_file_mmap+0xc0/0x140
> mmap_region+0x3e8/0x5b0
> do_mmap+0x280/0x460
> vm_mmap_pgoff+0xf4/0x128
> ksys_mmap_pgoff+0xb4/0x258
> __arm64_sys_mmap+0x34/0x48
> el0_svc_common+0x78/0x130
> el0_svc_handler+0x38/0x78
> el0_svc+0x8/0xc
>
> Fixes: 9980d744a0 ("mm, hugetlb: get rid of surplus page accounting tricks")
> Signed-off-by: Kai Shen <shenkai8@xxxxxxxxxx>
> Signed-off-by: Feilong Lin <linfeilong@xxxxxxxxxx>
> Reported-by: Wang Wang <wangwang2@xxxxxxxxxx>
You are right. I must have completely missed that put_page path
unconditionally takes the hugetlb_lock for hugetlb pages.
Thanks for fixing this. I think this should be marked for stable
because it is not hard to imagine a regular user might trigger this.
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/hugetlb.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 6cdc7b2..c1e7b81 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1574,8 +1574,9 @@ static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
> */
> if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
> SetPageHugeTemporary(page);
> + spin_unlock(&hugetlb_lock);
> put_page(page);
> - page = NULL;
> + return NULL;
> } else {
> h->surplus_huge_pages++;
> h->surplus_huge_pages_node[page_to_nid(page)]++;
> --
> 1.8.3.1
>
>
--
Michal Hocko
SUSE Labs
