Re: [PATCH] mm: fix panic caused by __page_handle_poison()

["HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>]

On Mon, Aug 30, 2021 at 06:07:56PM +0800, 王贇 wrote:
> By commit 510d25c92ec4 ("mm/hwpoison: disable pcp for
> page_handle_poison()"), __page_handle_poison() was
> introduced, and if we mark:
> 
> RET_A = dissolve_free_huge_page();
> RET_B = take_page_off_buddy();
> 
> then __page_handle_poison was supposed to return TRUE When
> RET_A == 0 && RET_B == TRUE
> 
> But since it failed to take care the case when RET_A is
> -EBUSY or -ENOMEM, and just return the ret as a bool which
> actually become TRUE, it break the original logical.

s/logical/logic/ ?

> 
> The following result is a huge page in freelist but was
> referenced as poisoned, and lead into the final panic:
> 
>   kernel BUG at mm/internal.h:95!
>   invalid opcode: 0000 [#1] SMP PTI
>   skip...
>   RIP: 0010:set_page_refcounted mm/internal.h:95 [inline]
>   RIP: 0010:remove_hugetlb_page+0x23c/0x240 mm/hugetlb.c:1371
>   skip...
>   Call Trace:
>    remove_pool_huge_page+0xe4/0x110 mm/hugetlb.c:1892
>    return_unused_surplus_pages+0x8d/0x150 mm/hugetlb.c:2272
>    hugetlb_acct_memory.part.91+0x524/0x690 mm/hugetlb.c:4017
> 
> This patch replace 'bool' with 'int' to handle RET_A correctly.
> 
> Reported-by: Abaci <abaci@linux.alibaba.com>
> Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>

Thank you very much, this fix is totally right.

Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>

Could you add the following tags, too?

Fixes: 510d25c92ec4 ("mm/hwpoison: disable pcp for page_handle_poison()")
Cc: <stable@vger.kernel.org> # 5.14

Thanks,
Naoya Horiguchi