From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754404AbdCHUqU (ORCPT ); Wed, 8 Mar 2017 15:46:20 -0500 Received: from mail-pg0-f52.google.com ([74.125.83.52]:33252 "EHLO mail-pg0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753778AbdCHUqS (ORCPT ); Wed, 8 Mar 2017 15:46:18 -0500 Date: Wed, 8 Mar 2017 12:16:16 -0800 From: Omar Sandoval To: Matt Fleming , Dave Young , Ingo Molnar Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: kexec regression since 4.9 caused by efi Message-ID: <20170308201616.GC8598@vader> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, everyone, Since 4.9, kexec results in the following panic on some of our servers: [ 0.001000] general protection fault: 0000 [#1] SMP [ 0.001000] Modules linked in: [ 0.001000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc1 #53 [ 0.001000] Hardware name: Wiwynn Leopard-Orv2/Leopard-DDR BW, BIOS LBM05 09/30/2016 [ 0.001000] task: ffffffff81e0e4c0 task.stack: ffffffff81e00000 [ 0.001000] RIP: 0010:virt_efi_set_variable+0x85/0x1a0 [ 0.001000] RSP: 0000:ffffffff81e03e18 EFLAGS: 00010202 [ 0.001000] RAX: afafafafafafafaf RBX: ffffffff81e3a4e0 RCX: 0000000000000007 [ 0.001000] RDX: ffffffff81e03e70 RSI: ffffffff81e3a4e0 RDI: ffff88407f8c2de0 [ 0.001000] RBP: ffffffff81e03e60 R08: 0000000000000000 R09: 0000000000000000 [ 0.001000] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff81e03e70 [ 0.001000] R13: 0000000000000007 R14: 0000000000000000 R15: 0000000000000000 [ 0.001000] FS: 0000000000000000(0000) GS:ffff881fff600000(0000) knlGS:0000000000000000 [ 0.001000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.001000] CR2: ffff88407f30f000 CR3: 0000001fff102000 CR4: 00000000000406b0 [ 0.001000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 0.001000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 0.001000] Call Trace: [ 0.001000] efi_delete_dummy_variable+0x7a/0x80 [ 0.001000] efi_enter_virtual_mode+0x3e2/0x494 [ 0.001000] start_kernel+0x392/0x418 [ 0.001000] ? set_init_arg+0x55/0x55 [ 0.001000] x86_64_start_reservations+0x2a/0x2c [ 0.001000] x86_64_start_kernel+0xea/0xed [ 0.001000] start_cpu+0x14/0x14 [ 0.001000] Code: 42 25 8d ff 80 3d 43 77 95 00 00 75 68 9c 8f 04 24 48 8b 05 3e 7d 7e 00 48 89 de 4d 89 f9 4d 89 f0 44 89 e9 4c 89 e2 48 8b 40 58 <48> 8b 78 58 31 c0 e8 90 e4 92 ff 48 8b 3c 24 48 c7 c6 2b 0a ca [ 0.001000] RIP: virt_efi_set_variable+0x85/0x1a0 RSP: ffffffff81e03e18 [ 0.001000] ---[ end trace 0bd213e540e9b19f ]--- [ 0.001000] Kernel panic - not syncing: Fatal exception [ 0.001000] ---[ end Kernel panic - not syncing: Fatal exception Booting normally (i.e., not kexec) still works. The decoded code is: 0: 42 25 8d ff 80 3d rex.X and $0x3d80ff8d,%eax 6: 43 77 95 rex.XB ja 0xffffffffffffff9e 9: 00 00 add %al,(%rax) b: 75 68 jne 0x75 d: 9c pushfq e: 8f 04 24 popq (%rsp) 11: 48 8b 05 3e 7d 7e 00 mov 0x7e7d3e(%rip),%rax # 0x7e7d56 18: 48 89 de mov %rbx,%rsi 1b: 4d 89 f9 mov %r15,%r9 1e: 4d 89 f0 mov %r14,%r8 21: 44 89 e9 mov %r13d,%ecx 24: 4c 89 e2 mov %r12,%rdx 27: 48 8b 40 58 mov 0x58(%rax),%rax 2b:* 48 8b 78 58 mov 0x58(%rax),%rdi <-- trapping instruction 2f: 31 c0 xor %eax,%eax 31: e8 90 e4 92 ff callq 0xffffffffff92e4c6 36: 48 8b 3c 24 mov (%rsp),%rdi 3a: 48 rex.W 3b: c7 .byte 0xc7 3c: c6 (bad) 3d: 2b 0a sub (%rdx),%ecx 3f: ca .byte 0xca If I'm reading this correctly, efi.systab->runtime == 0xafafafafafafafaf, and we're crashing when we try to dereference that. Here is the output of efi=debug from before the crash: [ 0.000000] Linux version 4.11.0-rc1 (osandov@devbig561.prn1.facebook.com) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-11) (GCC) ) #53 SMP Wed Mar 8 12:07:16 PST 2017 [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-4.6.7-34_fbk7_2504_g8275185 ro root=LABEL=/ ipv6.autoconf=0 erst_disable biosdevname=0 net.ifnames=0 fsck.repair=yes pcie_pme=nomsi netconsole=+6666@2401:db00:0011:b03e:face:0000:0009:0000/eth0,1514@2401:db00:eef0:a59::/02:90:fb:5b:b7:1e crashkernel=128M console=tty0 co nsole=ttyS1,57600 efi=debug [ 0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers' [ 0.000000] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers' [ 0.000000] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers' [ 0.000000] x86/fpu: xstate_offset[2]: 576, xstate_sizes[2]: 256 [ 0.000000] x86/fpu: Enabled xstate features 0x7, context size is 832 bytes, using 'standard' format. [ 0.000000] e820: BIOS-provided physical RAM map: [ 0.000000] BIOS-e820: [mem 0x0000000000000100-0x000000000009ffff] usable [ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000750bdfff] usable [ 0.000000] BIOS-e820: [mem 0x00000000750be000-0x0000000075ddbfff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000075ddc000-0x0000000075e32fff] ACPI data [ 0.000000] BIOS-e820: [mem 0x0000000075e33000-0x000000007642dfff] ACPI NVS [ 0.000000] BIOS-e820: [mem 0x000000007642e000-0x000000007bcd9fff] reserved [ 0.000000] BIOS-e820: [mem 0x000000007bcda000-0x000000007bcdafff] usable [ 0.000000] BIOS-e820: [mem 0x000000007bcdb000-0x000000007bd60fff] reserved [ 0.000000] BIOS-e820: [mem 0x000000007bd61000-0x000000007bffffff] usable [ 0.000000] BIOS-e820: [mem 0x000000007c000000-0x000000008fffffff] reserved [ 0.000000] BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed44fff] reserved [ 0.000000] BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000407fffffff] usable [ 0.000000] NX (Execute Disable) protection: active [ 0.000000] extended physical RAM map: [ 0.000000] reserve setup_data: [mem 0x0000000000000100-0x000000000009ffff] usable [ 0.000000] reserve setup_data: [mem 0x0000000000100000-0x000000000010006f] usable [ 0.000000] reserve setup_data: [mem 0x0000000000100070-0x00000000750bdfff] usable [ 0.000000] reserve setup_data: [mem 0x00000000750be000-0x0000000075ddbfff] reserved [ 0.000000] reserve setup_data: [mem 0x0000000075ddc000-0x0000000075e32fff] ACPI data [ 0.000000] reserve setup_data: [mem 0x0000000075e33000-0x000000007642dfff] ACPI NVS [ 0.000000] reserve setup_data: [mem 0x000000007642e000-0x000000007bcd9fff] reserved [ 0.000000] reserve setup_data: [mem 0x000000007bcda000-0x000000007bcdafff] usable [ 0.000000] reserve setup_data: [mem 0x000000007bcdb000-0x000000007bd60fff] reserved [ 0.000000] reserve setup_data: [mem 0x000000007bd61000-0x000000007bffffff] usable [ 0.000000] reserve setup_data: [mem 0x000000007c000000-0x000000008fffffff] reserved [ 0.000000] reserve setup_data: [mem 0x00000000fed1c000-0x00000000fed44fff] reserved [ 0.000000] reserve setup_data: [mem 0x00000000ff000000-0x00000000ffffffff] reserved [ 0.000000] reserve setup_data: [mem 0x0000000100000000-0x000000407fffffff] usable [ 0.000000] efi: EFI v2.40 by American Megatrends [ 0.000000] efi: ACPI=0x75f5c000 ACPI 2.0=0x75f5c000 ESRT=0x7bc4d018 SMBIOS=0xf05e0 SMBIOS 3.0=0x7bb2f000 MPS=0xfc9e0 [ 0.000000] efi: mem00: [Runtime Data |RUN| | | | | | | |WB|WT|WC|UC] range=[0x000000007642e000-0x000000007bc50fff] (88MB) [ 0.000000] efi: mem01: [Runtime Code |RUN| | | | | | | |WB|WT|WC|UC] range=[0x000000007bc51000-0x000000007bcd9fff] (0MB) [ 0.000000] efi: mem02: [Runtime Data |RUN| | | | | | | |WB|WT|WC|UC] range=[0x000000007bcdb000-0x000000007bd60fff] (0MB) [ 0.000000] efi: mem03: [Memory Mapped I/O |RUN| | | | | | | | | | |UC] range=[0x0000000080000000-0x000000008fffffff] (256MB) [ 0.000000] efi: mem04: [Memory Mapped I/O |RUN| | | | | | | | | | |UC] range=[0x00000000fed1c000-0x00000000fed44fff] (0MB) [ 0.000000] efi: mem05: [Memory Mapped I/O |RUN| | | | | | | | | | |UC] range=[0x00000000ff000000-0x00000000ffffffff] (16MB) [ 0.000000] SMBIOS 3.0.0 present. [ 0.000000] DMI: Wiwynn Leopard-Orv2/Leopard-DDR BW, BIOS LBM05 09/30/2016 [ 0.000000] e820: last_pfn = 0x4080000 max_arch_pfn = 0x400000000 [ 0.000000] x86/PAT: Configuration [0-7]: WB WC UC- UC WB WC UC- WT [ 0.000000] x2apic: enabled by BIOS, switching to x2apic ops [ 0.000000] e820: last_pfn = 0x7c000 max_arch_pfn = 0x400000000 [ 0.000000] esrt: Reserving ESRT space from 0x000000007bc4d018 to 0x000000007bc4d050. Reverting commit 8e80632fb23f ("efi/esrt: Use efi_mem_reserve() and avoid a kmalloc()") on top of v4.11-rc1 fixes the problem. Bisecting this was interesting: - Up until 8e80632fb23f ("efi/esrt: Use efi_mem_reserve() and avoid a kmalloc()"), kexec worked. - From 8e80632fb23f to 9d80448ac92b ("efi/arm64: Add debugfs node to dump UEFI runtime page tables"), kexec just hung after the "kexec_core: Starting new kernel" message. - From 3dad6f7f6975 ("x86/efi: Defer efi_esrt_init until after memblock_x86_fill") to 0a637ee61247 ("x86/efi: Allow invocation of arbitrary boot services"), kexec hit the BUG_ON(!efi.systab) in kexec_enter_virtual_mode(). - Finally, after 92dc33501bfb ("x86/efi: Round EFI memmap reservations to EFI_PAGE_SIZE"), I get the panic described above. Let me know if there is any more information I can provide. Thanks!