On 12/8/25 14:33, SHANMUGAM, SRINIVASAN wrote: > [AMD Official Use Only - AMD Internal Distribution Only] > >> -----Original Message----- >> From: Koenig, Christian <[email protected]> >> Sent: Friday, December 5, 2025 6:30 PM >> To: SHANMUGAM, SRINIVASAN <[email protected]>; >> Deucher, Alexander <[email protected]> >> Cc: [email protected] >> Subject: Re: [PATCH] drm/amdgpu: Reduce stack usage in >> amdgpu_userq_wait_ioctl() >> >> On 12/5/25 13:14, Srinivasan Shanmugam wrote: >>> Checked all the local variables in the function. Most of them are >>> small numbers or pointers and use very little stack space. The only >>> large item stored on the stack is struct drm_exec, and this is what >>> pushes the stack size over the limit. >>> >>> To fix this, struct drm_exec is now allocated with kmalloc() instead >>> of being placed on the stack. All call sites were updated to use a >>> pointer, and all cleanup paths now call drm_exec_fini() and kfree() to >>> release the memory safely. >>> >>> This reduces stack usage, fixes the below: >>> drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c:642:5: warning: stack >>> frame size (1176) exceeds limit (1024) in 'amdgpu_userq_wait_ioctl' >>> [-Wframe-larger-than] >> >> Mhm, I'm really wondering how that happens? The drm_exec object is >> intentionally >> so small that it can be allocated on the stack. >> >> What's going on here? > > Hi Christian, > > It looks like it only grows that large with sanitizers enabled — KASAN/UBSAN > inflate the frame, not drm_exec itself.
As long as that is not showing up with KASAN disabled I don't think there is a reason to fix this. Regards, Christian. > > Thanks! > Srini
