Messages in this thread Patch in this message | | | Date | Wed, 15 Jun 2022 13:18:23 +0800 | Subject | Re: Re: [PATCH v5 1/1] mm/memory-failure: disable unpoison once hw error happens | From | zhenwei pi <> |
| |
On 6/15/22 12:23, Oscar Salvador wrote: > On Wed, Jun 15, 2022 at 10:00:05AM +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@nec.com> >> Cc: David Hildenbrand <david@redhat.com> >> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com> >> --- > ... > ... >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >> index b85661cbdc4a..385b5e99bfc1 100644 >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -69,6 +69,8 @@ int sysctl_memory_failure_recovery __read_mostly = 1; >> >> atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0); >> >> +static bool hw_memory_failure; >> + >> static bool __page_handle_poison(struct page *page) >> { >> int ret; >> @@ -1768,6 +1770,9 @@ int memory_failure(unsigned long pfn, int flags) >> >> 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 we disable this, I would move this at the beginning of the function. > We do not really care whether the pfn is valid or getting the head of > the page, etc. > So, unless I'm missing something, this should be enough? >
Hi,
Because memory_failure() may be called by hardware error randomly, hw_memory_failure should be protected by mf_mutex to avoid this case: int unpoison_memory(unsigned long pfn) { ... if (hw_memory_failure) { } ... --> memory_failure() happens, and mark hw_memory_failure as true mutex_lock(&mf_mutex); }
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 385b5e99bfc1..ece15f07dee7 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -2100,6 +2100,12 @@ int unpoison_memory(unsigned long pfn) > static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL, > DEFAULT_RATELIMIT_BURST); > > + if (hw_memory_failure) { > + unpoison_pr_info("Unpoison: Disabled after HW memory failure\n", > + &unpoison_rs); > + ret -EOPNOTSUPP; > + } > + > if (!pfn_valid(pfn)) > return -ENXIO; > >
-- zhenwei pi
| |