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Message-ID: <5eb5dbc1-274a-4932-8c77-8000509deadb@redhat.com>
Date: Tue, 26 Aug 2025 12:58:28 +0200
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
Subject: Re: [PATCH v3] mm/memory-failure: fix
VM_BUG_ON_PAGE(PagePoisoned(page)) when unpoison memory
On 26.08.25 09:57, Miaohe Lin wrote:
> When I did memory failure tests, 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
>
> This scene can be identified by pfn_to_online_page() returning NULL.
> And ZONE_DEVICE pages are never expected, so we can simply fail if
> pfn_to_online_page() == NULL to fix the bug.
>
> Suggested-by: David Hildenbrand <david@...hat.com>
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Similar to
commit 96c804a6ae8c59a9092b3d5dd581198472063184
Author: David Hildenbrand <david@...hat.com>
Date: Fri Oct 18 20:19:23 2019 -0700
mm/memory-failure.c: don't access uninitialized memmaps in memory_failure()
We should check for pfn_to_online_page() to not access uninitialized
memmaps. Reshuffle the code so we don't have to duplicate the error
message.
Link: http://lkml.kernel.org/r/20191009142435.3975-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@...hat.com>
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319]
Acked-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: <stable@...r.kernel.org> [4.13+]
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
We should likely just use the exact same Fixes:
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319]
Not sure about CCing stable. This is a pure debugging feature (depends on DEBUG_KERNEL),
and someone really has to trigger it manually to provoke this. So I would not CC stable.
> ---
> v2:
> Use pfn_to_online_page per David. Thanks.
> v3:
> Simply fail if pfn_to_online_page() == NULL per David. Thanks.
> ---
> mm/memory-failure.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index c15ffee7d32b..212620308028 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -2572,7 +2572,9 @@ int unpoison_memory(unsigned long pfn)
> if (!pfn_valid(pfn))
> return -ENXIO;
>
> - p = pfn_to_page(pfn);
> + p = pfn_to_online_page(pfn);
> + if (!p)
> + return -EIO;
I think we can just drop the pfn_valid() check now. pfn_to_online_page() implies a pfn_valid() check.
--
Cheers
David / dhildenb
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