Messages in this thread | | | Date | Tue, 14 Jun 2022 08:22:10 +0800 | Subject | Re: Re: [PATCH v3 1/1] mm/memory-failure: don't allow to unpoison hw corrupted page | From | zhenwei pi <> |
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On 6/10/22 20:12, David Hildenbrand wrote: > On 10.06.22 13:46, 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. >> >> Do not allow to unpoison hardware corrupted page in unpoison_memory() 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@nec.com> >> Cc: David Hildenbrand <david@redhat.com> >> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com> >> --- >> mm/memory-failure.c | 59 +++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 59 insertions(+) >> >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >> index b85661cbdc4a..3124f428302c 100644 >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -2068,6 +2068,58 @@ static int __init memory_failure_init(void) >> } >> core_initcall(memory_failure_init); >> >> +/* >> + * Unpoisoning a hardware corrupted page with *NOT PRESENT* KPTE leads panic. >> + * Test a page is valid in the kernel mapping. >> + */ >> +static bool kmap_valid(struct page *page) >> +{ >> + unsigned long addr = (unsigned long)page_to_virt(page); >> + pgd_t *pgd; >> + p4d_t *p4d; >> + pud_t *pud; >> + pmd_t *pmd; >> + pte_t *pte; >> + >> + pgd = pgd_offset_k(addr); >> + if (pgd_none(*pgd)) >> + return false; >> + if (pgd_leaf(*pgd)) >> + return true; >> + if (pgd_bad(*pgd)) >> + return false; >> + >> + p4d = p4d_offset(pgd, addr); >> + if (p4d_none(*p4d)) >> + return false; >> + if (p4d_leaf(*p4d)) >> + return true; >> + if (p4d_bad(*p4d)) >> + return false; >> + >> + pud = pud_offset(p4d, addr); >> + if (pud_none(*pud)) >> + return false; >> + if (pud_leaf(*pud)) >> + return true; >> + if (pud_bad(*pud)) >> + return false; >> + >> + pmd = pmd_offset(pud, addr); >> + if (pmd_none(*pmd)) >> + return false; >> + if (pmd_leaf(*pmd)) >> + return true; >> + if (pmd_bad(*pmd)) >> + return false; >> + >> + pte = pte_offset_map(pmd, addr); >> + if (pte_none(*pte) || !pte_present(*pte)) >> + return false; >> + >> + return true; >> +} >> + >> #define unpoison_pr_info(fmt, pfn, rs) \ >> ({ \ >> if (__ratelimit(rs)) \ >> @@ -2109,6 +2161,13 @@ int unpoison_memory(unsigned long pfn) >> goto unlock_mutex; >> } >> >> + if (!kmap_valid(page)) { >> + unpoison_pr_info("Unpoison: Page was hardware poisoned %#lx\n", >> + pfn, &unpoison_rs); >> + ret = -EOPNOTSUPP; >> + goto unlock_mutex; >> + } >> + >> if (page_count(page) > 1) { >> unpoison_pr_info("Unpoison: Someone grabs the hwpoison page %#lx\n", >> pfn, &unpoison_rs); > > I really prefer just disabling the unpoisioning mechanism in case there > is a real hw injected error. >
Hi, Naoya & Andrew
What is your opinion?
-- zhenwei pi
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