* Thomas Zimmermann (tzimmermann@xxxxxxx) wrote: > Hi Hi Thomas, Thanks for the reply. > Am 15.12.24 um 19:18 schrieb Dr. David Alan Gilbert: > > Hey Gerd, Thomas, > > I've got the following oops that looks bochs-drm related on the current > > HEAD ( 4800575d8c0b2f354ab05ab1c4749e45e213bf73 ) and it's been there > > for at least a few days; this is > [...] > > > > The oops has : > > [ 78.463760][ T1] bochs_pci_driver_init+0x8a/0xc0 > > > > in it, hence why I'm blaming that. > > (Other odd observation, the Tuxen flicker heavily during booting!) > > > > [ 72.756014][ T1] bochs-drm 0000:00:02.0: vgaarb: deactivate vga console > > [ 72.758258][ T1] [drm] Found bochs VGA, ID 0xb0c5. > > [ 72.758793][ T1] [drm] Framebuffer size 16384 kB @ 0xfd000000, mmio @ 0xfebf0000. > > [ 72.767777][ T1] [drm] Initialized bochs-drm 1.0.0 for 0000:00:02.0 on minor 2 > > [ 72.839222][ T1] fbcon: bochs-drmdrmfb (fb1) is primary device > > [ 72.839311][ T1] fbcon: Remapping primary device, fb1, to tty 1-63 > > [ 78.402163][ T1] bochs-drm 0000:00:02.0: [drm] fb1: bochs-drmdrmfb frame buffer device > > [ 78.459984][ T1] BUG: unable to handle page fault for address: ffff8dd345604004 > > [ 78.463246][ T1] #PF: supervisor write access in kernel mode > > [ 78.463760][ T1] #PF: error_code(0x0002) - not-present page > > [ 78.463760][ T1] PGD 72001067 P4D 72001067 PUD 72002067 PMD 7fbe1067 PTE 800ffffffa9fb060 > > [ 78.463760][ T1] Oops: Oops: 0002 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI > > [ 78.463760][ T1] CPU: 2 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W N 6.13.0-rc2+ #363 6c653a430ed30aae3dac648429c492a2726da3d7 > > [ 78.463760][ T1] Tainted: [W]=WARN, [N]=TEST > > [ 78.463760][ T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014 > > [ 78.463760][ T1] RIP: 0010:devm_drm_dev_init_release+0x4e/0x140 > [...] > > > > [ 78.463760][ T1] ---[ end Kernel panic - not syncing: Fatal exception ]--- > > > > > > The config is a fairly full yes-config ish; see attached. > > Thanks for reporting. I've been able to reproduce the problem by setting > CONFIG_DEBUG_TEST_DRIVER_REMOVE <https://elixir.bootlin.com/linux/v6.13-rc2/K/ident/CONFIG_DEBUG_TEST_DRIVER_REMOVE>=y. Ah OK, so fairly obscure (I'm running something close to a all-yes-config because I'm mostly build testing obscure stuff). > The attached patch fixes the problem for me. Could you please test and > report back the results. That gets me a different oops; this was run with: qemu-system-x86_64 -M pc -cpu host --enable-kvm -smp 4 -m 2G -kernel /discs/fast/kernel/arch/x86/boot/bzImage -append "console=tty0 console=ttyS0 root=/dev/vdb1 single" -drive if=virtio,file=/discs/more/images/debian12-64scan.qcow2 It looks to me if it made the mistake of trying to print something in the middle of being removed: [ 73.569852][ T1] bochs-drm 0000:00:02.0: vgaarb: deactivate vga console [ 73.571802][ T1] [drm] Found bochs VGA, ID 0xb0c5. [ 73.572787][ T1] [drm] Framebuffer size 16384 kB @ 0xfd000000, mmio @ 0xfebf0000. [ 73.581626][ T1] [drm] Initialized bochs-drm 1.0.0 for 0000:00:02.0 on minor 2 [ 73.650048][ T1] fbcon: bochs-drmdrmfb (fb1) is primary device [ 73.650134][ T1] fbcon: Remapping primary device, fb1, to tty 1-63 [ 79.276550][ T1] bochs-drm 0000:00:02.0: [drm] fb1: bochs-drmdrmfb frame buffer device [ 79.346726][ T1] bochs-drm 0000:00:02.0: vgaarb: deactivate vga console [ 79.348731][ T1] BUG: kernel NULL pointer dereference, address: 000000000000020c [ 79.348799][ T1] #PF: supervisor write access in kernel mode [ 79.348857][ T1] #PF: error_code(0x0002) - not-present page [ 79.348913][ T1] PGD 0 P4D 0 [ 79.348999][ T1] Oops: Oops: 0002 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI [ 79.349107][ T1] CPU: 2 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W N 6.13.0-rc2+ #373 5a5c0ce8f09b0b72067981f01985e201a0118bb6 [ 79.349268][ T1] Tainted: [W]=WARN, [N]=TEST [ 79.349313][ T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014 [ 79.349377][ T1] RIP: 0010:fbcon_cursor+0xa9/0x3c0 [ 79.349524][ T1] Code: c0 05 00 00 66 89 44 24 06 e8 f3 35 2a fd 0f b7 bb c0 05 00 00 e8 27 b8 e9 fc 49 8d bc 24 0c 02 00 00 49 89 c7 e8 d7 3d 2a fd <45> 89 bc 24 0c 02 00 00 48 8d bd e0 05 00 00 e8 c3 3b 2a fd 44 8b [ 79.349628][ T1] RSP: 0018:ffffb927800136c0 EFLAGS: 00010046 [ 79.349716][ T1] RAX: 0000000000000000 RBX: ffff9835810a8800 RCX: 0000000000000000 [ 79.349808][ T1] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 79.349879][ T1] RBP: ffff983585d07000 R08: 0000000000000000 R09: 0000000000000000 [ 79.349952][ T1] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 79.350024][ T1] R13: 0000000000000000 R14: ffff983585d075e8 R15: 0000000000000032 [ 79.350101][ T1] FS: 0000000000000000(0000) GS:ffff9835fd200000(0000) knlGS:0000000000000000 [ 79.350196][ T1] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 79.350278][ T1] CR2: 000000000000020c CR3: 000000004d920000 CR4: 0000000000350ef0 [ 79.350344][ T1] Call Trace: [ 79.350373][ T1] <TASK> [ 79.350413][ T1] ? __die+0x23/0x80 [ 79.350540][ T1] ? page_fault_oops+0x21c/0x240 [ 79.350675][ T1] ? do_user_addr_fault+0x893/0x1180 [ 79.350798][ T1] ? srso_return_thunk+0x5/0x7f [ 79.350904][ T1] ? exc_page_fault+0x3f/0x180 [ 79.351066][ T1] ? exc_page_fault+0x87/0x180 [ 79.351211][ T1] ? asm_exc_page_fault+0x26/0x40 [ 79.351379][ T1] ? fbcon_cursor+0xa9/0x3c0 [ 79.351542][ T1] hide_cursor+0x66/0x1c0 [ 79.351656][ T1] vt_console_print+0x9b1/0xa40 [ 79.351813][ T1] ? srso_return_thunk+0x5/0x7f [ 79.351920][ T1] ? irq_trace+0x84/0xc0 [ 79.352029][ T1] ? srso_return_thunk+0x5/0x7f [ 79.352153][ T1] ? console_emit_next_record+0x1fe/0x440 [ 79.352254][ T1] console_emit_next_record+0x232/0x440 [ 79.352333][ T1] ? console_emit_next_record+0x1fe/0x440 [ 79.352450][ T1] console_flush_all+0x590/0x7c0 [ 79.352531][ T1] ? console_flush_all+0x26/0x7c0 [ 79.352601][ T1] console_unlock+0xf9/0x280 [ 79.352601][ T1] vprintk_emit+0x572/0x5c0 [ 79.352601][ T1] dev_vprintk_emit+0x70/0xc0 [ 79.352601][ T1] ? __mutex_lock+0x380/0xd40 [ 79.352601][ T1] dev_printk_emit+0x7f/0xc0 [ 79.352601][ T1] __dev_printk+0x89/0x100 [ 79.352601][ T1] _dev_info+0xba/0xf5 [ 79.352601][ T1] vga_remove_vgacon.cold+0x18/0xc0 [ 79.352601][ T1] aperture_remove_conflicting_pci_devices+0x142/0x1c0 [ 79.352601][ T1] ? __pfx_bochs_pci_probe+0x40/0x40 [ 79.352601][ T1] bochs_pci_probe+0x30/0x380 [ 79.352601][ T1] local_pci_probe+0x88/0x100 [ 79.352601][ T1] pci_call_probe+0x126/0x340 [ 79.352601][ T1] ? srso_return_thunk+0x5/0x7f [ 79.352601][ T1] ? pci_match_device+0x287/0x380 [ 79.352601][ T1] pci_device_probe+0x154/0x280 [ 79.352601][ T1] ? __pfx_pci_device_probe+0x40/0x40 [ 79.352601][ T1] really_probe+0x411/0x780 [ 79.352601][ T1] __driver_probe_device+0x194/0x280 [ 79.352601][ T1] driver_probe_device+0x6f/0x1c0 [ 79.352601][ T1] __driver_attach+0x204/0x380 [ 79.352601][ T1] ? __pfx___driver_attach+0x40/0x40 [ 79.352601][ T1] bus_for_each_dev+0xe3/0x180 [ 79.352601][ T1] driver_attach+0x3a/0x80 [ 79.352601][ T1] bus_add_driver+0x1fd/0x3c0 [ 79.352601][ T1] driver_register+0x11d/0x1c0 [ 79.352601][ T1] __pci_register_driver+0x105/0x140 [ 79.352601][ T1] bochs_pci_driver_init+0x8a/0xc0 [ 79.352601][ T1] ? __pfx_bochs_pci_driver_init+0x40/0x40 [ 79.352601][ T1] do_one_initcall+0xa7/0x500 [ 79.352601][ T1] do_initcalls+0x1d5/0x240 [ 79.352601][ T1] kernel_init_freeable+0x1e4/0x280 [ 79.352601][ T1] ? __pfx_kernel_init+0x40/0x40 [ 79.352601][ T1] kernel_init+0x2a/0x280 [ 79.352601][ T1] ret_from_fork+0x4d/0x80 [ 79.352601][ T1] ? __pfx_kernel_init+0x40/0x40 [ 79.352601][ T1] ret_from_fork_asm+0x22/0x80 [ 79.352601][ T1] </TASK> [ 79.352601][ T1] Modules linked in: [ 79.352601][ T1] CR2: 000000000000020c [ 79.352601][ T1] ---[ end trace 0000000000000000 ]--- [ 79.352601][ T1] RIP: 0010:fbcon_cursor+0xa9/0x3c0 [ 79.352601][ T1] Code: c0 05 00 00 66 89 44 24 06 e8 f3 35 2a fd 0f b7 bb c0 05 00 00 e8 27 b8 e9 fc 49 8d bc 24 0c 02 00 00 49 89 c7 e8 d7 3d 2a fd <45> 89 bc 24 0c 02 00 00 48 8d bd e0 05 00 00 e8 c3 3b 2a fd 44 8b [ 79.352601][ T1] RSP: 0018:ffffb927800136c0 EFLAGS: 00010046 [ 79.352601][ T1] RAX: 0000000000000000 RBX: ffff9835810a8800 RCX: 0000000000000000 [ 79.352601][ T1] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 79.352601][ T1] RBP: ffff983585d07000 R08: 0000000000000000 R09: 0000000000000000 [ 79.352601][ T1] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 79.352601][ T1] R13: 0000000000000000 R14: ffff983585d075e8 R15: 0000000000000032 [ 79.352601][ T1] FS: 0000000000000000(0000) GS:ffff9835fd200000(0000) knlGS:0000000000000000 [ 79.352601][ T1] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 79.352601][ T1] CR2: 000000000000020c CR3: 000000004d920000 CR4: 0000000000350ef0 [ 79.352601][ T1] Kernel panic - not syncing: Fatal exception [ 79.352601][ T1] Kernel Offset: 0xf800000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 79.352601][ T1] ---[ end Kernel panic - not syncing: Fatal exception ]--- > Best regards > Thomas > > > > > > Dave > > > > -- > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Frankenstrasse 146, 90461 Nuernberg, Germany > GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman > HRB 36809 (AG Nuernberg) > From bebba3b34d5df5aa7c882f080633b43ddb87f4ad Mon Sep 17 00:00:00 2001 > From: Thomas Zimmermann <tzimmermann@xxxxxxx> > Date: Mon, 16 Dec 2024 09:21:46 +0100 > Subject: [PATCH] drm/bochs: Do not put DRM device in PCI remove callback > > Removing the bochs PCI device should mark the DRM device as unplugged > without removing it. Hence clear the respective call to drm_dev_put() > from bochs_pci_remove(). > > Fixes a double unref in devm_drm_dev_init_release(). An example error > message is shown below: > > [ 32.958338] BUG: KASAN: use-after-free in drm_dev_put.part.0+0x1b/0x90 > [ 32.958850] Write of size 4 at addr ffff888152134004 by task (udev-worker)/591 > [ 32.959574] CPU: 3 UID: 0 PID: 591 Comm: (udev-worker) Tainted: G E 6.13.0-rc2-1-default+ #3417 > [ 32.960316] Tainted: [E]=UNSIGNED_MODULE > [ 32.960637] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-2-gc13ff2cd-prebuilt.qemu.org 04/01/2014 > [ 32.961429] Call Trace: > [ 32.961433] <TASK> > [ 32.961439] dump_stack_lvl+0x68/0x90 > [ 32.961452] print_address_description.constprop.0+0x88/0x330 > [ 32.961461] ? preempt_count_sub+0x14/0xc0 > [ 32.961473] print_report+0xe2/0x1d0 > [ 32.961479] ? srso_alias_return_thunk+0x5/0xfbef5 > [ 32.963725] ? __virt_addr_valid+0x143/0x320 > [ 32.964077] ? srso_alias_return_thunk+0x5/0xfbef5 > [ 32.964463] ? drm_dev_put.part.0+0x1b/0x90 > [ 32.964817] kasan_report+0xce/0x1a0 > [ 32.965123] ? drm_dev_put.part.0+0x1b/0x90 > [ 32.965474] kasan_check_range+0xff/0x1c0 > [ 32.965806] drm_dev_put.part.0+0x1b/0x90 > [ 32.966138] release_nodes+0x84/0xc0 > [ 32.966447] devres_release_all+0xd2/0x110 > [ 32.966788] ? __pfx_devres_release_all+0x10/0x10 > [ 32.967177] ? preempt_count_sub+0x14/0xc0 > [ 32.967523] device_unbind_cleanup+0x16/0xc0 > [ 32.967886] really_probe+0x1b7/0x570 > [ 32.968207] __driver_probe_device+0xca/0x1b0 > [ 32.968568] driver_probe_device+0x4a/0xf0 > [ 32.968907] __driver_attach+0x10b/0x290 > [ 32.969239] ? __pfx___driver_attach+0x10/0x10 > [ 32.969598] bus_for_each_dev+0xc0/0x110 > [ 32.969923] ? __pfx_bus_for_each_dev+0x10/0x10 > [ 32.970291] ? bus_add_driver+0x17a/0x2b0 > [ 32.970622] ? srso_alias_return_thunk+0x5/0xfbef5 > [ 32.971011] bus_add_driver+0x19a/0x2b0 > [ 32.971335] driver_register+0xd8/0x160 > [ 32.971671] ? __pfx_bochs_pci_driver_init+0x10/0x10 [bochs] > [ 32.972130] do_one_initcall+0xba/0x390 > [...] > > After unplugging the DRM device, clients will close their references. > Closing the final reference will also release the DRM device. > > Reported-by: Dr. David Alan Gilbert <dave@xxxxxxxxxxx> > Closes: https://lore.kernel.org/lkml/Z18dbfDAiFadsSdg@gallifrey/ > Fixes: 04826f588682 ("drm/bochs: Allocate DRM device in struct bochs_device") > Cc: Thomas Zimmermann <tzimmermann@xxxxxxx> > Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx> > Cc: virtualization@xxxxxxxxxxxxxxx > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> > --- > drivers/gpu/drm/tiny/bochs.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c > index 89a699370a59..c67e1f906785 100644 > --- a/drivers/gpu/drm/tiny/bochs.c > +++ b/drivers/gpu/drm/tiny/bochs.c > @@ -757,7 +757,6 @@ static void bochs_pci_remove(struct pci_dev *pdev) > > drm_dev_unplug(dev); > drm_atomic_helper_shutdown(dev); > - drm_dev_put(dev); > } > > static void bochs_pci_shutdown(struct pci_dev *pdev) > -- > 2.47.1 > -- -----Open up your eyes, open up your mind, open up your code ------- / Dr. David Alan Gilbert | Running GNU/Linux | Happy \ \ dave @ treblig.org | | In Hex / \ _________________________|_____ http://www.treblig.org |_______/
