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Shuicheng Lin authored
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 9377de4c ("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.comSigned-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
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