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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Linux 4.15-rc6 + xen-unstable: BUG: unable to handle kernel NULL pointer dereference at (null), [ 0.000000] IP: zero_resv_unavail+0x8e/0xe1
On 09/01/18 17:16, Pavel Tatashin wrote: > Hi Juergen, > > Do you have this patch applied: > > https://github.com/torvalds/linux/commit/e8c24773d6b2cd9bc8b36bd6e60beff599be14be Seems this hasn't made it to Linus yet ? I will give it a test and report back, thanks ! > > Thank you, > Pavel > > On 01/09/2018 11:10 AM, Juergen Gross wrote: >> On 09/01/18 16:29, Sander Eikelenboom wrote: >>> Since it's already rc7: >>> "Give me a subtle ping, Vasili. One subtle ping only, please." >> >> I like that film :-) :) -- Sander >> Pavel, can you please comment? Do you have an idea how to repair the >> issue or should we revert your patch in 4.15? >> >> >> Juergen >> >>> >>> On 04/01/18 21:02, Sander Eikelenboom wrote: >>>> On 04/01/18 12:44, Juergen Gross wrote: >>>>> On 04/01/18 11:17, Sander Eikelenboom wrote: >>>>>> Hi Boris / Juergen, >>>>>> >>>>>> First of all best wishes for a quite turbulent starting new year. >>>>>> >>>>>> Now the holidays are over I finally gotten to test a linux 4.15-rc6 >>>>>> kernel >>>>>> and experienced a crash in early dom0 boot on my system (AMD phenom x6). >>>>>> >>>>>> I tested some earlier linux 4.15 rc's but experienced crashes then as >>>>>> well, >>>>>> but didn't have time to setup serial console to send them in >>>>>> (and waited to see if the issue Boris fixed with AMD PCI 64bit bar's >>>>>> could be it). >>>>>> >>>>>> But since that patch went in before 4.15 rc6, that doesn't seem to be >>>>>> the issue. >>>>>> So it could be that the culprit went in pretty earlier in the 4.15 cycle. >>>>>> >>>>>> The 4.15-rc6 kernel boots fine on bare metal, as does a 4.14.6 kernel on >>>>>> xen-unstable. >>>>>> >>>>>> Hopefully you have a pointer to what is wrong, if not i can try to do a >>>>>> bisect. >>>>> >>>>> A bisect would be very welcome. >>>> >>>> Hi Juergen / Boris / Pavel, >>>> >>>> Bisection result is: >>>> >>>> a4a3ede2132ae0863e2d43e06f9b5697c51a7a3b is the first bad commit >>>> commit a4a3ede2132ae0863e2d43e06f9b5697c51a7a3b >>>> Author: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> >>>> Date: Wed Nov 15 17:36:31 2017 -0800 >>>> >>>> mm: zero reserved and unavailable struct pages >>>> >>>> Some memory is reserved but unavailable: not present in >>>> memblock.memory >>>> (because not backed by physical pages), but present in >>>> memblock.reserved. >>>> Such memory has backing struct pages, but they are not initialized by >>>> going through __init_single_page(). >>>> >>>> In some cases these struct pages are accessed even if they do not >>>> contain any data. One example is page_to_pfn() might access >>>> page->flags >>>> if this is where section information is stored (CONFIG_SPARSEMEM, >>>> SECTION_IN_PAGE_FLAGS). >>>> >>>> One example of such memory: trim_low_memory_range() unconditionally >>>> reserves from pfn 0, but e820__memblock_setup() might provide the >>>> exiting memory from pfn 1 (i.e. KVM). >>>> >>>> Since struct pages are zeroed in __init_single_page(), and not during >>>> allocation time, we must zero such struct pages explicitly. >>>> >>>> The patch involves adding a new memblock iterator: >>>> for_each_resv_unavail_range(i, p_start, p_end) >>>> >>>> Which iterates through reserved && !memory lists, and we zero struct >>>> pages >>>> explicitly by calling mm_zero_struct_page(). >>>> >>>> === >>>> >>>> Here is more detailed example of problem that this patch is >>>> addressing: >>>> >>>> Run tested on qemu with the following arguments: >>>> >>>> -enable-kvm -cpu kvm64 -m 512 -smp 2 >>>> >>>> This patch reports that there are 98 unavailable pages. >>>> >>>> They are: pfn 0 and pfns in range [159, 255]. >>>> >>>> Note, trim_low_memory_range() reserves only pfns in range [0, 15], it >>>> does >>>> not reserve [159, 255] ones. >>>> >>>> e820__memblock_setup() reports linux that the following physical >>>> ranges are >>>> available: >>>> [1 , 158] >>>> [256, 130783] >>>> >>>> Notice, that exactly unavailable pfns are missing! >>>> >>>> Now, lets check what we have in zone 0: [1, 131039] >>>> >>>> pfn 0, is not part of the zone, but pfns [1, 158], are. >>>> >>>> However, the bigger problem we have if we do not initialize these >>>> struct >>>> pages is with memory hotplug. Because, that path operates at 2M >>>> boundaries (section_nr). And checks if 2M range of pages is hot >>>> removable. It starts with first pfn from zone, rounds it down to 2M >>>> boundary (sturct pages are allocated at 2M boundaries when vmemmap is >>>> created), and checks if that section is hot removable. In this case >>>> start with pfn 1 and convert it down to pfn 0. Later pfn is converted >>>> to struct page, and some fields are checked. Now, if we do not zero >>>> struct pages, we get unpredictable results. >>>> >>>> In fact when CONFIG_VM_DEBUG is enabled, and we explicitly set all >>>> vmemmap memory to ones, the following panic is observed with kernel >>>> test >>>> without this patch applied: >>>> >>>> BUG: unable to handle kernel NULL pointer dereference at >>>> (null) >>>> IP: is_pageblock_removable_nolock+0x35/0x90 >>>> PGD 0 P4D 0 >>>> Oops: 0000 [#1] PREEMPT >>>> ... >>>> task: ffff88001f4e2900 task.stack: ffffc90000314000 >>>> RIP: 0010:is_pageblock_removable_nolock+0x35/0x90 >>>> Call Trace: >>>> ? is_mem_section_removable+0x5a/0xd0 >>>> show_mem_removable+0x6b/0xa0 >>>> dev_attr_show+0x1b/0x50 >>>> sysfs_kf_seq_show+0xa1/0x100 >>>> kernfs_seq_show+0x22/0x30 >>>> seq_read+0x1ac/0x3a0 >>>> kernfs_fop_read+0x36/0x190 >>>> ? security_file_permission+0x90/0xb0 >>>> __vfs_read+0x16/0x30 >>>> vfs_read+0x81/0x130 >>>> SyS_read+0x44/0xa0 >>>> entry_SYSCALL_64_fastpath+0x1f/0xbd >>>> >>>> Link: >>>> http://lkml.kernel.org/r/20171013173214.27300-7-pasha.tatashin@xxxxxxxxxx >>>> Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> >>>> Reviewed-by: Steven Sistare <steven.sistare@xxxxxxxxxx> >>>> Reviewed-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx> >>>> Reviewed-by: Bob Picco <bob.picco@xxxxxxxxxx> >>>> Tested-by: Bob Picco <bob.picco@xxxxxxxxxx> >>>> Acked-by: Michal Hocko <mhocko@xxxxxxxx> >>>> Cc: Alexander Potapenko <glider@xxxxxxxxxx> >>>> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> >>>> Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> >>>> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> >>>> Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx> >>>> Cc: David S. Miller <davem@xxxxxxxxxxxxx> >>>> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> >>>> Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx> >>>> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> >>>> Cc: Ingo Molnar <mingo@xxxxxxxxxx> >>>> Cc: Mark Rutland <mark.rutland@xxxxxxx> >>>> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> >>>> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> >>>> Cc: Michal Hocko <mhocko@xxxxxxxxxx> >>>> Cc: Sam Ravnborg <sam@xxxxxxxxxxxx> >>>> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> >>>> Cc: Will Deacon <will.deacon@xxxxxxx> >>>> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >>>> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> >>>> >>>> :040000 040000 b0422cb4f5ef60f5bc7f0686d135c869680c603d >>>> 51ef20afe641afceaf5530b83b4f1b9a51563939 M include >>>> :040000 040000 55be7a5dd879578dc3f88bec059bcc392e3f1a1c >>>> b4c9f81df05629bb034b6d0bdc0454579f2986fe M mm >>>> >>>> >>>> -- >>>> Sander >>>> >>>>> >>>>> Juergen >>>>> >>>>>> >>>>>> -- >>>>>> Sander >>>>>> >>>>>> Attached: .config and full serial log >>>>>> >>>>>> 0.000000] ACPI: Early table checksum verification disabled >>>>>> [ 0.000000] ACPI: RSDP 0x00000000000FB100 000014 (v00 ACPIAM) >>>>>> [ 0.000000] ACPI: RSDT 0x00000000C7F90000 000048 (v01 MSI OEMSLIC >>>>>> 20100913 MSFT 00000097) >>>>>> [ 0.000000] ACPI: FACP 0x00000000C7F90200 000084 (v01 7640MS A7640100 >>>>>> 20100913 MSFT 00000097) >>>>>> [ 0.000000] ACPI: DSDT 0x00000000C7F905E0 009427 (v01 A7640 A7640100 >>>>>> 00000100 INTL 20051117) >>>>>> [ 0.000000] ACPI: FACS 0x00000000C7F9E000 000040 >>>>>> [ 0.000000] ACPI: APIC 0x00000000C7F90390 000088 (v01 7640MS A7640100 >>>>>> 20100913 MSFT 00000097) >>>>>> [ 0.000000] ACPI: MCFG 0x00000000C7F90420 00003C (v01 7640MS OEMMCFG >>>>>> 20100913 MSFT 00000097) >>>>>> [ 0.000000] ACPI: SLIC 0x00000000C7F90460 000176 (v01 MSI OEMSLIC >>>>>> 20100913 MSFT 00000097) >>>>>> [ 0.000000] ACPI: OEMB 0x00000000C7F9E040 000072 (v01 7640MS A7640100 >>>>>> 20100913 MSFT 00000097) >>>>>> [ 0.000000] ACPI: SRAT 0x00000000C7F9A5E0 000108 (v03 AMD FAM_F_10 >>>>>> 00000002 AMD 00000001) >>>>>> [ 0.000000] ACPI: HPET 0x00000000C7F9A6F0 000038 (v01 7640MS OEMHPET >>>>>> 20100913 MSFT 00000097) >>>>>> [ 0.000000] ACPI: IVRS 0x00000000C7F9A730 000110 (v01 AMD RD890S >>>>>> 00202031 AMD 00000000) >>>>>> [ 0.000000] ACPI: SSDT 0x00000000C7F9A840 000DA4 (v01 A M I POWERNOW >>>>>> 00000001 AMD 00000001) >>>>>> [ 0.000000] ACPI: Local APIC address 0xfee00000 >>>>>> [ 0.000000] Setting APIC routing to Xen PV. >>>>>> [ 0.000000] NUMA turned off >>>>>> [ 0.000000] Faking a node at [mem >>>>>> 0x0000000000000000-0x000000007fffffff] >>>>>> [ 0.000000] NODE_DATA(0) allocated [mem 0x7fc15000-0x7fc1efff] >>>>>> [ 0.000000] tsc: Fast TSC calibration using PIT >>>>>> [ 0.000000] Zone ranges: >>>>>> [ 0.000000] DMA [mem 0x0000000000001000-0x0000000000ffffff] >>>>>> [ 0.000000] DMA32 [mem 0x0000000001000000-0x000000007fffffff] >>>>>> [ 0.000000] Normal empty >>>>>> [ 0.000000] Movable zone start for each node >>>>>> [ 0.000000] Early memory node ranges >>>>>> [ 0.000000] node 0: [mem 0x0000000000001000-0x0000000000095fff] >>>>>> [ 0.000000] node 0: [mem 0x0000000000100000-0x000000007fffffff] >>>>>> [ 0.000000] Initmem setup node 0 [mem >>>>>> 0x0000000000001000-0x000000007fffffff] >>>>>> [ 0.000000] On node 0 totalpages: 524181 >>>>>> [ 0.000000] DMA zone: 64 pages used for memmap >>>>>> [ 0.000000] DMA zone: 21 pages reserved >>>>>> [ 0.000000] DMA zone: 3989 pages, LIFO batch:0 >>>>>> [ 0.000000] DMA32 zone: 8128 pages used for memmap >>>>>> [ 0.000000] DMA32 zone: 520192 pages, LIFO batch:31 >>>>>> [ 0.000000] BUG: unable to handle kernel NULL pointer dereference at >>>>>> (null) >>>>>> [ 0.000000] IP: zero_resv_unavail+0x8e/0xe1 >>>>>> [ 0.000000] PGD 0 P4D 0 >>>>>> [ 0.000000] Oops: 0002 [#1] SMP >>>>>> [ 0.000000] Modules linked in: >>>>>> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted >>>>>> 4.15.0-rc6-20180104-linus-doflr+ #1 >>>>>> [ 0.000000] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS >>>>>> V1.8B1 09/13/2010 >>>>>> [ 0.000000] RIP: e030:zero_resv_unavail+0x8e/0xe1 >>>>>> [ 0.000000] RSP: e02b:ffffffff82803d68 EFLAGS: 00010006 >>>>>> [ 0.000000] RAX: 0000000000000000 RBX: 0000000000000001 RCX: >>>>>> 0000000000000010 >>>>>> [ 0.000000] RDX: 000000000007ffff RSI: 0000000000000100 RDI: >>>>>> ffffea0002000000 >>>>>> [ 0.000000] RBP: ffffffff82803d70 R08: ffffea0002000000 R09: >>>>>> 0000000000000002 >>>>>> [ 0.000000] R10: 0000000000000002 R11: 0000000000000003 R12: >>>>>> ffffea0000000000 >>>>>> [ 0.000000] R13: 0000000000000000 R14: ffffffff82803f20 R15: >>>>>> 0000000000000000 >>>>>> [ 0.000000] FS: 0000000000000000(0000) GS:ffffffff82e16000(0000) >>>>>> knlGS:0000000000000000 >>>>>> [ 0.000000] CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>>>> [ 0.000000] CR2: 0000000000000000 CR3: 0000000002823000 CR4: >>>>>> 0000000000000660 >>>>>> [ 0.000000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: >>>>>> 0000000000000000 >>>>>> [ 0.000000] DR3: 0000000000000000 DR6: 0000000000000000 DR7: >>>>>> 0000000000000000 >>>>>> [ 0.000000] Call Trace: >>>>>> [ 0.000000] ? free_area_init_nodes+0x690/0x69f >>>>>> [ 0.000000] ? zone_sizes_init+0x4b/0x50 >>>>>> [ 0.000000] ? xen_pagetable_init+0x13/0x43f >>>>>> [ 0.000000] ? memblock_find_dma_reserve+0x141/0x15b >>>>>> [ 0.000000] ? memblock_find_dma_reserve+0x150/0x15b >>>>>> [ 0.000000] ? numa_init+0x43c/0x453 >>>>>> [ 0.000000] ? setup_arch+0x7a0/0x87f >>>>>> [ 0.000000] ? start_kernel+0x58/0x3a8 >>>>>> [ 0.000000] ? iommu_shutdown_noop+0x10/0x10 >>>>>> [ 0.000000] ? xen_start_kernel+0x528/0x534 >>>>>> [ 0.000000] Code: da 49 c1 e0 06 4d 01 e0 48 8b 44 24 08 48 8d 0c 1a >>>>>> 48 05 ff 0f 00 00 48 c1 e8 0c 48 39 c8 76 16 4c 89 c7 b9 10 00 00 00 44 >>>>>> 89 e8 <f3> ab 48 ff c3 49 83 c0 40 eb d2 6a 00 55 31 d2 49 c7 c0 90 78 >>>>>> [ 0.000000] RIP: zero_resv_unavail+0x8e/0xe1 RSP: ffffffff82803d68 >>>>>> [ 0.000000] CR2: 0000000000000000 >>>>>> [ 0.000000] ---[ end trace b788f32e38f6de39 ]--- >>>>>> [ 0.000000] Kernel panic - not syncing: Attempted to kill the idle >>>>>> task! >>>>>> (XEN) [2018-01-04 09:52:49.218] Hardware Dom0 crashed: rebooting machine >>>>>> in 5 seconds. >>>>>> >>>>> >>>> >>> >>> >> _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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