linux-kernel - Re: [PATCH v6 1/1] mm/memory-failure: disable unpoison once hw error happens

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Date:   Wed, 15 Jun 2022 10:34:06 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     zhenwei pi <pizhenwei@...edance.com>
CC:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "david@...hat.com" <david@...hat.com>,
        "linmiaohe@...wei.com" <linmiaohe@...wei.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Oscar Salvador <osalvador@...e.de>
Subject: Re: [PATCH v6 1/1] mm/memory-failure: disable unpoison once hw error
 happens

On Wed, Jun 15, 2022 at 05:32:09PM +0800, zhenwei pi wrote:
> Currently unpoison_memory(unsigned long pfn) is designed for soft
> poison(hwpoison-inject) only. Since 17fae1294ad9d, the KPTE gets
> cleared on a x86 platform once hardware memory corrupts.
> 
> Unpoisoning a hardware corrupted page puts page back buddy only,
> the kernel has a chance to access the page with *NOT PRESENT* KPTE.
> This leads BUG during accessing on the corrupted KPTE.
> 
> Suggested by David&Naoya, disable unpoison mechanism when a real HW error
> happens to avoid BUG like this:
> 
>  Unpoison: Software-unpoisoned page 0x61234
>  BUG: unable to handle page fault for address: ffff888061234000
>  #PF: supervisor write access in kernel mode
>  #PF: error_code(0x0002) - not-present page
>  PGD 2c01067 P4D 2c01067 PUD 107267063 PMD 10382b063 PTE 800fffff9edcb062
>  Oops: 0002 [#1] PREEMPT SMP NOPTI
>  CPU: 4 PID: 26551 Comm: stress Kdump: loaded Tainted: G   M       OE     5.18.0.bm.1-amd64 #7
>  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) ...
>  RIP: 0010:clear_page_erms+0x7/0x10
>  Code: ...
>  RSP: 0000:ffffc90001107bc8 EFLAGS: 00010246
>  RAX: 0000000000000000 RBX: 0000000000000901 RCX: 0000000000001000
>  RDX: ffffea0001848d00 RSI: ffffea0001848d40 RDI: ffff888061234000
>  RBP: ffffea0001848d00 R08: 0000000000000901 R09: 0000000000001276
>  R10: 0000000000000003 R11: 0000000000000000 R12: 0000000000000001
>  R13: 0000000000000000 R14: 0000000000140dca R15: 0000000000000001
>  FS:  00007fd8b2333740(0000) GS:ffff88813fd00000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: ffff888061234000 CR3: 00000001023d2005 CR4: 0000000000770ee0
>  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>  PKRU: 55555554
>  Call Trace:
>   <TASK>
>   prep_new_page+0x151/0x170
>   get_page_from_freelist+0xca0/0xe20
>   ? sysvec_apic_timer_interrupt+0xab/0xc0
>   ? asm_sysvec_apic_timer_interrupt+0x1b/0x20
>   __alloc_pages+0x17e/0x340
>   __folio_alloc+0x17/0x40
>   vma_alloc_folio+0x84/0x280
>   __handle_mm_fault+0x8d4/0xeb0
>   handle_mm_fault+0xd5/0x2a0
>   do_user_addr_fault+0x1d0/0x680
>   ? kvm_read_and_reset_apf_flags+0x3b/0x50
>   exc_page_fault+0x78/0x170
>   asm_exc_page_fault+0x27/0x30
> 
> Fixes: 847ce401df392 ("HWPOISON: Add unpoisoning support")
> Fixes: 17fae1294ad9d ("x86/{mce,mm}: Unmap the entire page if the whole page is affected and poisoned")
> Cc: Naoya Horiguchi <naoya.horiguchi@....com>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Oscar Salvador <osalvador@...e.de>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Acked-by: David Hildenbrand <david@...hat.com>
> Signed-off-by: zhenwei pi <pizhenwei@...edance.com>

Thank you very much.

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