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SubjectRe: [PATCH] gpu: drm: drm_mm: Fix a sleep-in-atomic-context bug in show_leaks()
On Sat, Sep 01, 2018 at 01:32:54PM +0100, Chris Wilson wrote:
> Quoting Jia-Ju Bai (2018-09-01 13:20:41)
> > The driver may sleep with holding a spinlock.
> >
> > The function call paths (from bottom to top) in Linux-4.16 are:
> >
> > [FUNC] kmalloc(GFP_KERNEL)
> > drivers/gpu/drm/drm_mm.c, 130:
> > kmalloc in show_leaks
> > drivers/gpu/drm/drm_mm.c, 913:
> > show_leaks in drm_mm_takedown
> > drivers/gpu/drm/drm_vma_manager.c, 107:
> > drm_mm_takedown in drm_vma_offset_manager_destroy
> > drivers/gpu/drm/drm_vma_manager.c, 106:
> > _raw_write_lock in drm_vma_offset_manager_destroy
> >
> > [FUNC] kmalloc(GFP_KERNEL)
> > drivers/gpu/drm/drm_mm.c, 130:
> > kmalloc in show_leaks
> > drivers/gpu/drm/drm_mm.c, 913:
> > show_leaks in drm_mm_takedown
> > drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 71:
> > drm_mm_takedown in amdgpu_vram_mgr_fini
> > drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 70:
> > spin_lock in amdgpu_vram_mgr_fini
> >
> > [FUNC] kmalloc(GFP_KERNEL)
> > drivers/gpu/drm/drm_mm.c, 130:
> > kmalloc in show_leaks
> > drivers/gpu/drm/drm_mm.c, 913:
> > show_leaks in drm_mm_takedown
> > drivers/gpu/drm/ttm/ttm_bo_manager.c, 128:
> > drm_mm_takedown in ttm_bo_man_takedown
> > drivers/gpu/drm/ttm/ttm_bo_manager.c, 126:
> > spin_lock in ttm_bo_man_takedown
> >
> > To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.
>
> The bug are above, since those spinlocks do not protect the data and
> imply use-after-free.

Adding amdgpu, since that's where the bug seems to be.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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