[v4] mm/memory-failure: fix VM_BUG_ON_PAGE(PagePoisoned(page)) when unpoison memory

[PATCH v4] mm/memory-failure: fix VM_BUG_ON_PAGE(PagePoisoned(page)) when unpoison memory

Posted by Miaohe Lin 1 month ago

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.

Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online")
Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
v2:
  Use pfn_to_online_page per David. Thanks.
v3:
  Simply fail if pfn_to_online_page() == NULL per David. Thanks.
v4:
  Add Fixes tag and remove pfn_valid check per David. Thanks.
---
 mm/memory-failure.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index c15ffee7d32b..4af8875b07b6 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2569,10 +2569,9 @@ 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_page(pfn);
+	p = pfn_to_online_page(pfn);
+	if (!p)
+		return -EIO;
 	folio = page_folio(p);
 
 	mutex_lock(&mf_mutex);
-- 
2.33.0

Re: [PATCH v4] mm/memory-failure: fix VM_BUG_ON_PAGE(PagePoisoned(page)) when unpoison memory

Posted by David Hildenbrand 1 month ago

On 28.08.25 04:46, 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.
> 
> Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online")
> Suggested-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers

David / dhildenb