The patch titled Subject: mm/memory-failure: don't allow to unpoison hw corrupted page has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-memory-failure-dont-allow-to-unpoison-hw-corrupted-page.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: zhenwei pi pizhenwei@bytedance.com Subject: mm/memory-failure: don't allow to unpoison hw corrupted page Date: Sat, 4 Jun 2022 18:32:29 +0800

Currently unpoison_memory(unsigned long pfn) is designed for soft poison(hwpoison-inject) only. Unpoisoning a hardware corrupted page puts page back buddy only, 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

Link: https://lkml.kernel.org/r/20220604103229.3378591-1-pizhenwei@bytedance.com Signed-off-by: zhenwei pi pizhenwei@bytedance.com Cc: Naoya Horiguchi naoya.horiguchi@nec.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/memory-failure.c | 8 ++++++++ 1 file changed, 8 insertions(+)

--- a/mm/memory-failure.c~mm-memory-failure-dont-allow-to-unpoison-hw-corrupted-page +++ a/mm/memory-failure.c @@ -2090,6 +2090,7 @@ int unpoison_memory(unsigned long pfn) { struct page *page; struct page *p; + pte_t *kpte; int ret = -EBUSY; int freeit = 0; static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL, @@ -2101,6 +2102,13 @@ int unpoison_memory(unsigned long pfn) p = pfn_to_page(pfn); page = compound_head(p);

+ kpte = virt_to_kpte((unsigned long)page_to_virt(p)); + if (kpte && !pte_present(*kpte)) { + unpoison_pr_info("Unpoison: Page was hardware poisoned %#lx\n", + pfn, &unpoison_rs); + return -EPERM; + } + mutex_lock(&mf_mutex);

if (!PageHWPoison(p)) { _

Patches currently in -mm which might be from pizhenwei@bytedance.com are

mm-memory-failure-dont-allow-to-unpoison-hw-corrupted-page.patch