linux-kernel - Re: [PATCH] mm: fix panic caused by __page_handle

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Message-ID: <20210831091134.GA1075738@hori.linux.bs1.fc.nec.co.jp>
Date:   Tue, 31 Aug 2021 09:11:35 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     王贇 <yun.wang@...ux.alibaba.com>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        "open list:HWPOISON MEMORY FAILURE HANDLING" <linux-mm@...ck.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: fix panic caused by __page_handle_poison()

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@...ux.alibaba.com>
> Signed-off-by: Michael Wang <yun.wang@...ux.alibaba.com>

Thank you very much, this fix is totally right.

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

Could you add the following tags, too?

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

Thanks,
Naoya Horiguchi