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e94c55b8e0
Starting with commit f295c8cfec
("drm/nouveau: fix dma syncing warning with debugging on.")
the following oops occures:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 6 PID: 1013 Comm: Xorg.bin Tainted: G E 5.11.0-desktop-rc0+ #2
Hardware name: Acer Aspire VN7-593G/Pluto_KLS, BIOS V1.11 08/01/2018
RIP: 0010:nouveau_bo_sync_for_device+0x40/0xb0 [nouveau]
Call Trace:
nouveau_bo_validate+0x5d/0x80 [nouveau]
nouveau_gem_ioctl_pushbuf+0x662/0x1120 [nouveau]
? nouveau_gem_ioctl_new+0xf0/0xf0 [nouveau]
drm_ioctl_kernel+0xa6/0xf0 [drm]
drm_ioctl+0x1f4/0x3a0 [drm]
? nouveau_gem_ioctl_new+0xf0/0xf0 [nouveau]
nouveau_drm_ioctl+0x50/0xa0 [nouveau]
__x64_sys_ioctl+0x7e/0xb0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
---[ end trace ccfb1e7f4064374f ]---
RIP: 0010:nouveau_bo_sync_for_device+0x40/0xb0 [nouveau]
The underlying problem is not introduced by the commit, yet it uncovered the
underlying issue. The cited commit relies on valid pages. This is not given for
due to some bugs. For now, just warn and work around the issue by just ignoring
the bad ttm objects.
Below is some debug info gathered while debugging this issue:
nouveau 0000:01:00.0: DRM: ttm_dma->num_pages: 2048
nouveau 0000:01:00.0: DRM: ttm_dma->pages is NULL
nouveau 0000:01:00.0: DRM: ttm_dma: 00000000e96058e7
nouveau 0000:01:00.0: DRM: ttm_dma->page_flags:
nouveau 0000:01:00.0: DRM: ttm_dma: Populated: 1
nouveau 0000:01:00.0: DRM: ttm_dma: No Retry: 0
nouveau 0000:01:00.0: DRM: ttm_dma: SG: 256
nouveau 0000:01:00.0: DRM: ttm_dma: Zero Alloc: 0
nouveau 0000:01:00.0: DRM: ttm_dma: Swapped: 0
Signed-off-by: Tobias Klausmann <tobias.klausmann@freenet.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210313222159.3346-1-tobias.klausmann@freenet.de
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.