Re: [PATCH v2] mm/hugetlb: Don't put_page in lock of hugetlb_lock

[Oscar Salvador]

On Mon, May 06, 2019 at 10:06:38PM +0800, 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>
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>

Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>

-- 
Oscar Salvador
SUSE L3