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Message-ID:
<BLAPR10MB521793485093FDB448F7B2E5FDE92@BLAPR10MB5217.namprd10.prod.outlook.com>
Date: Thu, 30 Jan 2025 18:36:54 +0000
From: Thomas Tai <thomas.tai@...cle.com>
To: "mhkelley58@...il.com" <mhkelley58@...il.com>,
"haiyangz@...rosoft.com"
<haiyangz@...rosoft.com>,
"wei.liu@...nel.org" <wei.liu@...nel.org>,
"decui@...rosoft.com" <decui@...rosoft.com>,
"drawat.floss@...il.com"
<drawat.floss@...il.com>,
"javierm@...hat.com" <javierm@...hat.com>,
Helge
Deller <deller@....de>, "daniel@...ll.ch" <daniel@...ll.ch>,
"airlied@...il.com" <airlied@...il.com>,
"tzimmermann@...e.de"
<tzimmermann@...e.de>
CC: "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
Thomas Tai
<thomas.tai@...cle.com>
Subject: hyper_bf soft lockup on Azure Gen2 VM when taking kdump or executing
kexec
Hi Michael,
We see an issue with the mainline kernel on the Azure Gen 2 VM when trying to induce a kernel panic with sysrq commands. The VM would hang with soft lockup. A similar issue happens when executing kexec on the VM. This issue is seen only with Gen2 VMs(with UEFI boot). Gen1 VMs with bios boot are fine.
git bisect identifies the issue is cased by the commit 20ee2ae8c5899 ("fbdev/hyperv_fb: Fix logic error for Gen2 VMs in hvfb_getmem()" ). However, reverting the commit would cause the frame buffer not to work on the Gen2 VM.
Do you have any hints on what caused this issue?
To reproduce the issue with kdump:
- Install mainline kernel on an Azure Gen 2 VM and trigger a kdump
- echo 1 > /proc/sys/kernel/sysrq
- echo c > /proc/sysrq-trigger
To reproduce the issue with executing kexec:
- Install mainline kernel on Azure Gen 2 VM and use kexec
- sudo kexec -l /boot/vmlinuz --initrd=/boot/initramfs.img --command-line="$( cat /proc/cmdline )"
- sudo kexec -e
Thank you,
Thomas
--- soft lockup log---
[ 1.690032] efifb: probing for efifb
[ 1.693989] efifb: framebuffer at 0x40000000, using 3072k, total 3072k
[ 1.700996] efifb: mode is 1024x768x32, linelength=4096, pages=1
[ 1.706999] efifb: scrolling: redraw
[ 1.710981] efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0
[ 1.716806] Console: switching to colour frame buffer device 128x48
[ 29.176649] watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [swapper/0:1]
[ 29.176655] Modules linked in:
[ 29.176658] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.13.0+ #1
[ 29.176661] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 03/08/2024
[ 29.176663] RIP: 0010:fast_imageblit.isra.0+0x2de/0x460
[ 29.176669] Code: 07 49 21 f1 41 83 e1 01 46 8b 4c 8c 40 44 89 09 41 89 d1 4c 8d 79 08 41 c0 e9 06 49 21 f1 41 83 e1 03 46 8b 4c 8c 40 45 89 0e <41> 89 d1 4c 8d 71 0c 41 c0 e9 05 49 21 f1 41 83 e1 07 46 8b 4c 8c
[ 29.176671] RSP: 0018:ffffc900000437a8 EFLAGS: 00010246
[ 29.176673] RAX: 0000000000000400 RBX: 0000000000000005 RCX: ffffc900006bb140
[ 29.176674] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff888012146600
[ 29.176675] RBP: 0000000000000080 R08: ffffc900006bb000 R09: 0000000000000000
[ 29.176676] R10: 0000000000000001 R11: ffff888012146580 R12: 0000000000001000
[ 29.176677] R13: ffff88801214658a R14: ffffc900006bb144 R15: ffffc900006bb148
[ 29.176678] FS: 0000000000000000(0000) GS:ffff888026a00000(0000) knlGS:0000000000000000
[ 29.176680] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 29.176681] CR2: 00007f8bc160c238 CR3: 000000002ac38002 CR4: 00000000003706b0
[ 29.176683] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 29.176684] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 29.176685] Call Trace:
[ 29.176687] <IRQ>
[ 29.176690] ? watchdog_timer_fn+0x220/0x2a0
[ 29.176695] ? __pfx_watchdog_timer_fn+0x10/0x10
[ 29.176697] ? __hrtimer_run_queues+0x112/0x2b0
[ 29.176702] ? hrtimer_interrupt+0x108/0x270
[ 29.176704] ? sched_clock_cpu+0x60/0x1a0
[ 29.176708] ? __sysvec_hyperv_stimer0+0x32/0x60
[ 29.176712] ? sysvec_hyperv_stimer0+0x70/0x90
[ 29.176715] </IRQ>
[ 29.176716] <TASK>
[ 29.176716] ? asm_sysvec_hyperv_stimer0+0x1a/0x20
[ 29.176722] ? fast_imageblit.isra.0+0x2de/0x460
[ 29.176724] cfb_imageblit+0x433/0x470
[ 29.176726] bit_putcs+0x291/0x570
[ 29.176731] ? __pfx_bit_putcs+0x10/0x10
[ 29.176733] fbcon_putcs+0x139/0x1a0
[ 29.176735] do_update_region+0xf1/0x110
[ 29.176740] redraw_screen+0x22f/0x290
[ 29.176743] do_bind_con_driver.isra.0+0x2ab/0x3d0
[ 29.176745] do_take_over_console+0x3a/0x50
[ 29.176747] do_fbcon_takeover+0x5c/0xe0
[ 29.176749] fbcon_fb_registered+0x4f/0x70
[ 29.176751] do_register_framebuffer+0x1bc/0x2a0
[ 29.176755] devm_register_framebuffer+0x28/0x90
[ 29.176757] efifb_probe+0x544/0x720
[ 29.176760] platform_probe+0x43/0xb0
[ 29.176763] really_probe+0xd9/0x390
[ 29.176767] ? __pfx___device_attach_driver+0x10/0x10
[ 29.176769] __driver_probe_device+0x78/0x160
[ 29.176771] driver_probe_device+0x1e/0xa0
[ 29.176773] __device_attach_driver+0x99/0x130
[ 29.176775] bus_for_each_drv+0x98/0xf0
[ 29.176777] __device_attach+0xbc/0x1f0
[ 29.176779] bus_probe_device+0x8d/0xb0
[ 29.176781] device_add+0x4f1/0x6e0
[ 29.176785] platform_device_add+0xfa/0x260
[ 29.176787] sysfb_init+0x109/0x120
[ 29.176791] ? __pfx_sysfb_init+0x10/0x10
[ 29.176793] do_one_initcall+0x5b/0x330
[ 29.176796] do_initcalls+0xac/0x130
[ 29.176800] kernel_init_freeable+0x134/0x1e0
[ 29.176802] ? __pfx_kernel_init+0x10/0x10
[ 29.176806] kernel_init+0x1a/0x1d0
[ 29.176808] ret_from_fork+0x34/0x50
[ 29.176813] ? __pfx_kernel_init+0x10/0x10
[ 29.176815] ret_from_fork_asm+0x1a/0x30
[ 29.176819] </TASK>
[ 432.306986] fb0: EFI VGA frame buffer device
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