linux-kernel - Re: [PATCH v2] mm/memory-failure: fix VM_BUG_ON_PAGE(PagePoisoned(page)) when unpoison memory

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Message-ID: <06a45f8a-0981-40a2-a12a-5964fcdace13@redhat.com>
Date: Thu, 19 Dec 2024 13:18:44 +0100
From: David Hildenbrand <david@...hat.com>
To: Miaohe Lin <linmiaohe@...wei.com>, akpm@...ux-foundation.org
Cc: nao.horiguchi@...il.com, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH v2] mm/memory-failure: fix
 VM_BUG_ON_PAGE(PagePoisoned(page)) when unpoison memory

On 19.12.24 12:52, Miaohe Lin wrote:
> When I did memory failure tests recently, below panic occurs:
> 
> page dumped because: VM_BUG_ON_PAGE(PagePoisoned(page))
> kernel BUG at include/linux/page-flags.h:616!
> Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
> CPU: 3 PID: 720 Comm: bash Not tainted 6.10.0-rc1-00195-g148743902568 #40
> RIP: 0010:unpoison_memory+0x2f3/0x590
> RSP: 0018:ffffa57fc8787d60 EFLAGS: 00000246
> RAX: 0000000000000037 RBX: 0000000000000009 RCX: ffff9be25fcdc9c8
> RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff9be25fcdc9c0
> RBP: 0000000000300000 R08: ffffffffb4956f88 R09: 0000000000009ffb
> R10: 0000000000000284 R11: ffffffffb4926fa0 R12: ffffe6b00c000000
> R13: ffff9bdb453dfd00 R14: 0000000000000000 R15: fffffffffffffffe
> FS:  00007f08f04e4740(0000) GS:ffff9be25fcc0000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000564787a30410 CR3: 000000010d4e2000 CR4: 00000000000006f0
> Call Trace:
>   <TASK>
>   unpoison_memory+0x2f3/0x590
>   simple_attr_write_xsigned.constprop.0.isra.0+0xb3/0x110
>   debugfs_attr_write+0x42/0x60
>   full_proxy_write+0x5b/0x80
>   vfs_write+0xd5/0x540
>   ksys_write+0x64/0xe0
>   do_syscall_64+0xb9/0x1d0
>   entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f08f0314887
> RSP: 002b:00007ffece710078 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007f08f0314887
> RDX: 0000000000000009 RSI: 0000564787a30410 RDI: 0000000000000001
> RBP: 0000564787a30410 R08: 000000000000fefe R09: 000000007fffffff
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000009
> R13: 00007f08f041b780 R14: 00007f08f0417600 R15: 00007f08f0416a00
>   </TASK>
> Modules linked in: hwpoison_inject
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:unpoison_memory+0x2f3/0x590
> RSP: 0018:ffffa57fc8787d60 EFLAGS: 00000246
> RAX: 0000000000000037 RBX: 0000000000000009 RCX: ffff9be25fcdc9c8
> RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff9be25fcdc9c0
> RBP: 0000000000300000 R08: ffffffffb4956f88 R09: 0000000000009ffb
> R10: 0000000000000284 R11: ffffffffb4926fa0 R12: ffffe6b00c000000
> R13: ffff9bdb453dfd00 R14: 0000000000000000 R15: fffffffffffffffe
> FS:  00007f08f04e4740(0000) GS:ffff9be25fcc0000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000564787a30410 CR3: 000000010d4e2000 CR4: 00000000000006f0
> Kernel panic - not syncing: Fatal exception
> Kernel Offset: 0x31c00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
> ---[ end Kernel panic - not syncing: Fatal exception ]---
> 
> The root cause is that unpoison_memory() tries to check the PG_HWPoison
> flags of an uninitialized page. So VM_BUG_ON_PAGE(PagePoisoned(page)) is
> triggered. This can be reproduced by below steps:
> 1.Offline memory block:
>   echo offline > /sys/devices/system/memory/memory12/state
> 2.Get offlined memory pfn:
>   page-types -b n -rlN
> 3.Write pfn to unpoison-pfn
>   echo <pfn> > /sys/kernel/debug/hwpoison/unpoison-pfn
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> ---
> v2: Use pfn_to_online_page per David. Thanks.
> ---
>   mm/memory-failure.c | 14 +++++++++++---
>   1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index a7b8ccd29b6f..02be0596ce67 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -2556,10 +2556,18 @@ int unpoison_memory(unsigned long pfn)
>   	static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
>   					DEFAULT_RATELIMIT_BURST);
>   
> -	if (!pfn_valid(pfn))
> -		return -ENXIO;
> +	p = pfn_to_online_page(pfn);
> +	if (!p) {
> +		struct dev_pagemap *pgmap;
>   
> -	p = pfn_to_page(pfn);
> +		if (!pfn_valid(pfn))
> +			return -ENXIO;
> +		pgmap = get_dev_pagemap(pfn, NULL);
> +		if (!pgmap)
> +			return -ENXIO;
> +		put_dev_pagemap(pgmap);
> +		p = pfn_to_page(pfn);
> +	}

Hm, I wonder if we can do anything reasonable with ZONE_DEVICE pages here?

CCing Dan, maybe he knows if this interface used to do something 
reasonable with ZONE_DEVICE pages.

Also, I'm not sure about using the page after doing the 
put_dev_pagemap(). Likely we would have to do that at the before exiting 
from this function.

-- 
Cheers,

David / dhildenb