The patch titled Subject: mm/memory-failure: disable unpoison once hw error happens has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-memory-failure-disable-unpoison-once-hw-error-happens.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: disable unpoison once hw error happens Date: Wed, 15 Jun 2022 17:32:09 +0800

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

Link: https://lkml.kernel.org/r/20220615093209.259374-2-pizhenwei@bytedance.com Fixes: 847ce401df392 ("HWPOISON: Add unpoisoning support") Fixes: 17fae1294ad9d ("x86/{mce,mm}: Unmap the entire page if the whole page is affected and poisoned") Signed-off-by: zhenwei pi pizhenwei@bytedance.com Acked-by: David Hildenbrand david@redhat.com Acked-by: Naoya Horiguchi naoya.horiguchi@nec.com Cc: Oscar Salvador osalvador@suse.de Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

Documentation/vm/hwpoison.rst | 3 ++- drivers/base/memory.c | 2 +- include/linux/mm.h | 1 + mm/hwpoison-inject.c | 2 +- mm/madvise.c | 2 +- mm/memory-failure.c | 12 ++++++++++++ 6 files changed, 18 insertions(+), 4 deletions(-)

--- a/Documentation/vm/hwpoison.rst~mm-memory-failure-disable-unpoison-once-hw-error-happens +++ a/Documentation/vm/hwpoison.rst @@ -120,7 +120,8 @@ Testing unpoison-pfn Software-unpoison page at PFN echoed into this file. This way a page can be reused again. This only works for Linux - injected failures, not for real memory failures. + injected failures, not for real memory failures. Once any hardware + memory failure happens, this feature is disabled.

Note these injection interfaces are not stable and might change between kernel versions --- a/drivers/base/memory.c~mm-memory-failure-disable-unpoison-once-hw-error-happens +++ a/drivers/base/memory.c @@ -558,7 +558,7 @@ static ssize_t hard_offline_page_store(s if (kstrtoull(buf, 0, &pfn) < 0) return -EINVAL; pfn >>= PAGE_SHIFT; - ret = memory_failure(pfn, 0); + ret = memory_failure(pfn, MF_SW_SIMULATED); if (ret == -EOPNOTSUPP) ret = 0; return ret ? ret : count; --- a/include/linux/mm.h~mm-memory-failure-disable-unpoison-once-hw-error-happens +++ a/include/linux/mm.h @@ -3232,6 +3232,7 @@ enum mf_flags { MF_MUST_KILL = 1 << 2, MF_SOFT_OFFLINE = 1 << 3, MF_UNPOISON = 1 << 4, + MF_SW_SIMULATED = 1 << 5, }; extern int memory_failure(unsigned long pfn, int flags); extern void memory_failure_queue(unsigned long pfn, int flags); --- a/mm/hwpoison-inject.c~mm-memory-failure-disable-unpoison-once-hw-error-happens +++ a/mm/hwpoison-inject.c @@ -48,7 +48,7 @@ static int hwpoison_inject(void *data, u

inject: pr_info("Injecting memory failure at pfn %#lx\n", pfn); - err = memory_failure(pfn, 0); + err = memory_failure(pfn, MF_SW_SIMULATED); return (err == -EOPNOTSUPP) ? 0 : err; }

--- a/mm/madvise.c~mm-memory-failure-disable-unpoison-once-hw-error-happens +++ a/mm/madvise.c @@ -1112,7 +1112,7 @@ static int madvise_inject_error(int beha } else { pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n", pfn, start); - ret = memory_failure(pfn, MF_COUNT_INCREASED); + ret = memory_failure(pfn, MF_COUNT_INCREASED | MF_SW_SIMULATED); if (ret == -EOPNOTSUPP) ret = 0; } --- a/mm/memory-failure.c~mm-memory-failure-disable-unpoison-once-hw-error-happens +++ a/mm/memory-failure.c @@ -69,6 +69,8 @@ int sysctl_memory_failure_recovery __rea

atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);

+static bool hw_memory_failure __read_mostly = false; + static bool __page_handle_poison(struct page *page) { int ret; @@ -1768,6 +1770,9 @@ int memory_failure(unsigned long pfn, in

mutex_lock(&mf_mutex);

+ if (!(flags & MF_SW_SIMULATED)) + hw_memory_failure = true; + p = pfn_to_online_page(pfn); if (!p) { res = arch_memory_failure(pfn, flags); @@ -2103,6 +2108,13 @@ int unpoison_memory(unsigned long pfn)

mutex_lock(&mf_mutex);

+ if (hw_memory_failure) { + unpoison_pr_info("Unpoison: Disabled after HW memory failure %#lx\n", + pfn, &unpoison_rs); + ret = -EOPNOTSUPP; + goto unlock_mutex; + } + if (!PageHWPoison(p)) { unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n", pfn, &unpoison_rs); _

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

mm-memory-failure-disable-unpoison-once-hw-error-happens.patch