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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 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 :-) 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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