Shuicheng Lin
205e5c4b20
Here is the failure stack:
[ 12.988209] ------------[ cut here ]------------
[ 12.988216] UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
[ 12.988232] shift exponent 64 is too large for 64-bit type 'long unsigned int'
[ 12.988235] CPU: 4 PID: 1310 Comm: gnome-shell Tainted: G U 6.9.0-rc6+prerelease1158+ #19
[ 12.988237] Hardware name: Intel Corporation Raptor Lake Client Platform/RPL-S ADP-S DDR5 UDIMM CRB, BIOS RPLSFWI1.R00.3301.A02.2208050712 08/05/2022
[ 12.988239] Call Trace:
[ 12.988240] <TASK>
[ 12.988242] dump_stack_lvl+0xd7/0xf0
[ 12.988248] dump_stack+0x10/0x20
[ 12.988250] ubsan_epilogue+0x9/0x40
[ 12.988253] __ubsan_handle_shift_out_of_bounds+0x10e/0x170
[ 12.988260] dma_resv_reserve_fences.cold+0x2b/0x48
[ 12.988262] ? ww_mutex_lock_interruptible+0x3c/0x110
[ 12.988267] drm_exec_prepare_obj+0x45/0x60 [drm_exec]
[ 12.988271] ? vm_bind_ioctl_ops_execute+0x5b/0x740 [xe]
[ 12.988345] vm_bind_ioctl_ops_execute+0x78/0x740 [xe]
It is caused by the value 0 of parameter num_fences in function
drm_exec_prepare_obj. And lead to in function __rounddown_pow_of_two,
"0 - 1" causes the shift-out-of-bounds.
By design drm_exec_prepare_obj() should be called only when there are
fences to be reserved. If num_fences is 0, calling drm_exec_lock_obj()
is sufficient as was done in commit 9377de4cb3 ("drm/xe/vm: Avoid
reserving zero fences")
Cc: Nirmoy Das <nirmoy.das@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://lore.kernel.org/all/24d4a9a9-c622-4f56-8672-21f4c6785476@amd.com
Link: https://patchwork.freedesktop.org/patch/msgid/20240507130411.630361-1-shuicheng.lin@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
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 reStructuredText 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.