Messages in this thread Patch in this message | | | Date | Mon, 6 Jun 2022 15:20:27 +0800 | Subject | Re: Re: Re: [PATCH] mm/memory-failure: don't allow to unpoison hw corrupted page | From | zhenwei pi <> |
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On 6/6/22 12:32, HORIGUCHI NAOYA(堀口 直也) wrote: > On Sun, Jun 05, 2022 at 12:24:24PM +0800, zhenwei pi wrote: >> >> >> On 6/5/22 02:56, Andrew Morton wrote: >>> On Sat, 4 Jun 2022 18:32:29 +0800 zhenwei pi <pizhenwei@bytedance.com> wrote: >>> >>>> 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. > > Thank you for the patch. I think this will be helpful for integration testing. > > You mention "hardware corrupted page" as the condition of this bug, and I > think that it means a real hardware error, but this BUG seems to be > triggered when we use mce-inject or APEI (these are also software injection > without corrupting the memory physically). So the actual condition is > "when memory_failure() is called by MCE handler"? >
Yes, I use QEMU to emulate a 'real hardware error' by command: virsh qemu-monitor-command vm --hmp mce 0 9 0xbd000000000000c0 0xd 0x61234000 0x8c
>>>> >>>> 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 >>> >>> Thanks. >>> >>>> --- a/mm/memory-failure.c >>>> +++ b/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); > > This can prevent unpoison for hwpoison on 4kB pages, but not for hugetlb pages, > where I see the similar BUG as follows (even with applying your patch): > > [ 917.806712] BUG: unable to handle page fault for address: ffff9f7bb3201000 > [ 917.810144] #PF: supervisor write access in kernel mode > [ 917.812588] #PF: error_code(0x0002) - not-present page > [ 917.815007] PGD 104801067 P4D 104801067 PUD 10006b063 PMD 1052d0063 PTE 800ffffeccdfe062 > [ 917.818768] Oops: 0002 [#1] PREEMPT SMP PTI > [ 917.820759] CPU: 0 PID: 7774 Comm: test_alloc_gene Tainted: G M OE 5.18.0-v5.18-220606-0942-029-ge4dcc+ #47 > [ 917.825720] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1.fc35 04/01/2014 > [ 917.829762] RIP: 0010:clear_page_erms+0x7/0x10 > [ 917.831867] Code: 48 89 47 18 48 89 47 20 48 89 47 28 48 89 47 30 48 89 47 38 48 8d 7f 40 75 d9 90 c3 0f 1f 80 00 00 00 00 b9 00 10 00 00 31 c0 <f3> aa c3 cc cc cc cc cc cc 48 85 ff 0f 84 d3 00 00 00 0f b6 0f 4c > [ 917.840540] RSP: 0000:ffffab49c25ebdf0 EFLAGS: 00010246 > [ 917.842839] RAX: 0000000000000000 RBX: ffffd538c4cc8000 RCX: 0000000000001000 > [ 917.845835] RDX: 0000000080000000 RSI: 00007f2aeb600000 RDI: ffff9f7bb3201000 > [ 917.848687] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > [ 917.851377] R10: 0000000000000002 R11: ffff9f7b87e3a2a0 R12: 0000000000000000 > [ 917.854035] R13: 0000000000000001 R14: ffffd538c4cc8000 R15: ffff9f7bc002a5d8 > [ 917.856539] FS: 00007f2aebad3740(0000) GS:ffff9f7bbbc00000(0000) knlGS:0000000000000000 > [ 917.859229] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 917.861149] CR2: ffff9f7bb3201000 CR3: 0000000107726003 CR4: 0000000000170ef0 > [ 917.863433] Call Trace: > [ 917.864266] <TASK> > [ 917.864961] clear_huge_page+0x147/0x270 > [ 917.866236] hugetlb_fault+0x440/0xad0 > [ 917.867366] handle_mm_fault+0x270/0x290 > [ 917.868532] do_user_addr_fault+0x1c3/0x680 > [ 917.869768] exc_page_fault+0x6c/0x160 > [ 917.870912] ? asm_exc_page_fault+0x8/0x30 > [ 917.872082] asm_exc_page_fault+0x1e/0x30 > [ 917.873220] RIP: 0033:0x7f2aeb8ba367 > > I don't think of a workaround for this now ... >
Could you please tell me how to reproduce this issue?
>>>> + return -EPERM; > > Is -EOPNOTSUPP a better error code? >
OK!
>>>> + } >>>> + >>>> mutex_lock(&mf_mutex); >>>> if (!PageHWPoison(p)) { >>> >>> I guess we don't want to let fault injection crash the kernel, so a >>> cc:stable seems appropriate here. >>> >>> Can we think up a suitable Fixes: commit? I'm suspecting this bug has >>> been there for a long time? >>> >> >> Sure! >> >> 2009-Dec-16, hwpoison_unpoison() was introduced into linux in commit: >> 847ce401df392("HWPOISON: Add unpoisoning support") >> ... >> There is no hardware level unpoisioning, so this cannot be used for real >> memory errors, only for software injected errors. >> ... >> >> We can find that this function should be used for software level unpoisoning >> only in both commit log and comment in source code. unfortunately there is >> no check in function hwpoison_unpoison(). >> >> >> 2020-May-20, 17fae1294ad9d("x86/{mce,mm}: Unmap the entire page if the whole >> page is affected and poisoned") >> >> This clears KPTE, and leads BUG(described in this patch) during unpoisoning >> the hardware corrupted page. >> >> >> Fixes: 847ce401df392("HWPOISON: Add unpoisoning support") >> Fixes: 17fae1294ad9d("x86/{mce,mm}: Unmap the entire page if the whole page >> is affected and poisoned") >> >> Cc: Wu Fengguang <fengguang.wu@intel.com> >> Cc: Tony Luck <tony.luck@intel.com>. > > Thanks for checking the history, I agree with sending to stable. > > Thanks, > Naoya Horiguchi
-- zhenwei pi
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