Messages in this thread | | | Subject | Re: [PATCH] drm/fb-helper: only unmap if buffer not null | From | Thomas Zimmermann <> | Date | Tue, 2 Mar 2021 11:06:01 +0100 |
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Hi
Am 02.03.21 um 04:29 schrieb Tong Zhang: > Hi Tomas, > > I think the issue could be possibly caused by the following, > Please correct me if I'm wrong. > > drm_fb_helper_single_fb_probe() can fail with > "Cannot find any crtc or sizes" > which will cause fb_helper->funcs->fb_probe not being called, > thus fb_helper->buffer remains NULL -- > Since there could be the case that the fb_probe is never called, > a subsequent modprobe -r will cause the following > drm_client_buffer_vunmap(NULL) in drm_fbdev_cleanup()
Thanks! I added Fixes tags to your patch and merged it into drm-misc-fixes.
Best regards Thomas
> > Best, > - Tong > > On Mon, Mar 1, 2021 at 3:26 AM Thomas Zimmermann <tzimmermann@suse.de> wrote: >> >> Hi >> >> Am 28.02.21 um 05:46 schrieb Tong Zhang: >>> drm_fbdev_cleanup() can be called when fb_helper->buffer is null, hence >>> fb_helper->buffer should be checked before calling >>> drm_client_buffer_vunmap(). This buffer is also checked in >>> drm_client_framebuffer_delete(), so we should also do the same thing for >>> drm_client_buffer_vunmap(). >> >> I think a lot of drivers are affected by this problem; probably most of >> the ones that use the generic fbdev code. How did you produce the error? >> >> What I'm more concerned about is why the buffer is NULL. Was ther eno >> hotplug event? Do you have a display attached? >> >> Best regards >> Thomas >> >> >>> >>> [ 199.128742] RIP: 0010:drm_client_buffer_vunmap+0xd/0x20 >>> [ 199.129031] Code: 43 18 48 8b 53 20 49 89 45 00 49 89 55 08 5b 44 89 e0 41 5c 41 5d 41 5e 5d >>> c3 0f 1f 00 53 48 89 fb 48 8d 7f 10 e8 73 7d a1 ff <48> 8b 7b 10 48 8d 73 18 5b e9 75 53 fc ff 0 >>> f 1f 44 00 00 48 b8 00 >>> [ 199.130041] RSP: 0018:ffff888103f3fc88 EFLAGS: 00010282 >>> [ 199.130329] RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff8214d46d >>> [ 199.130733] RDX: 1ffffffff079c6b9 RSI: 0000000000000246 RDI: ffffffff83ce35c8 >>> [ 199.131119] RBP: ffff888103d25458 R08: 0000000000000001 R09: fffffbfff0791761 >>> [ 199.131505] R10: ffffffff83c8bb07 R11: fffffbfff0791760 R12: 0000000000000000 >>> [ 199.131891] R13: ffff888103d25468 R14: ffff888103d25418 R15: ffff888103f18120 >>> [ 199.132277] FS: 00007f36fdcbb6a0(0000) GS:ffff88815b400000(0000) knlGS:0000000000000000 >>> [ 199.132721] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> [ 199.133033] CR2: 0000000000000010 CR3: 0000000103d26000 CR4: 00000000000006f0 >>> [ 199.133420] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >>> [ 199.133807] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >>> [ 199.134195] Call Trace: >>> [ 199.134333] drm_fbdev_cleanup+0x179/0x1a0 >>> [ 199.134562] drm_fbdev_client_unregister+0x2b/0x40 >>> [ 199.134828] drm_client_dev_unregister+0xa8/0x180 >>> [ 199.135088] drm_dev_unregister+0x61/0x110 >>> [ 199.135315] mgag200_pci_remove+0x38/0x52 [mgag200] >>> [ 199.135586] pci_device_remove+0x62/0xe0 >>> [ 199.135806] device_release_driver_internal+0x148/0x270 >>> [ 199.136094] driver_detach+0x76/0xe0 >>> [ 199.136294] bus_remove_driver+0x7e/0x100 >>> [ 199.136521] pci_unregister_driver+0x28/0xf0 >>> [ 199.136759] __x64_sys_delete_module+0x268/0x300 >>> [ 199.137016] ? __ia32_sys_delete_module+0x300/0x300 >>> [ 199.137285] ? call_rcu+0x3e4/0x580 >>> [ 199.137481] ? fpregs_assert_state_consistent+0x4d/0x60 >>> [ 199.137767] ? exit_to_user_mode_prepare+0x2f/0x130 >>> [ 199.138037] do_syscall_64+0x33/0x40 >>> [ 199.138237] entry_SYSCALL_64_after_hwframe+0x44/0xae >>> [ 199.138517] RIP: 0033:0x7f36fdc3dcf7 >>> >>> Signed-off-by: Tong Zhang <ztong0001@gmail.com> >>> --- >>> drivers/gpu/drm/drm_fb_helper.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c >>> index b9a616737c0e..f6baa2046124 100644 >>> --- a/drivers/gpu/drm/drm_fb_helper.c >>> +++ b/drivers/gpu/drm/drm_fb_helper.c >>> @@ -2048,7 +2048,7 @@ static void drm_fbdev_cleanup(struct drm_fb_helper *fb_helper) >>> >>> if (shadow) >>> vfree(shadow); >>> - else >>> + else if (fb_helper->buffer) >>> drm_client_buffer_vunmap(fb_helper->buffer); >>> >>> drm_client_framebuffer_delete(fb_helper->buffer); >>> >> >> -- >> Thomas Zimmermann >> Graphics Driver Developer >> SUSE Software Solutions Germany GmbH >> Maxfeldstr. 5, 90409 Nürnberg, Germany >> (HRB 36809, AG Nürnberg) >> Geschäftsführer: Felix Imendörffer >> > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel >
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer
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