[1/3] dma_resv: prime lockdep annotations
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  • [1/3] dma_resv: prime lockdep annotations
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Daniel Vetter Nov. 4, 2019, 5:37 p.m. UTC
Full audit of everyone:

- i915, radeon, amdgpu should be clean per their maintainers.

- vram helpers should be fine, they don't do command submission, so
  really no business holding struct_mutex while doing copy_*_user. But
  I haven't checked them all.

- panfrost seems to dma_resv_lock only in panfrost_job_push, which
  looks clean.

- v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(),
  copying from/to userspace happens all in v3d_lookup_bos which is
  outside of the critical section.

- vmwgfx has a bunch of ioctls that do their own copy_*_user:
  - vmw_execbuf_process: First this does some copies in
    vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself.
    Then comes the usual ttm reserve/validate sequence, then actual
    submission/fencing, then unreserving, and finally some more
    copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of
    details, but looks all safe.
  - vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be
    seen, seems to only create a fence and copy it out.
  - a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be
    found there.
  Summary: vmwgfx seems to be fine too.

- virtio: There's virtio_gpu_execbuffer_ioctl, which does all the
  copying from userspace before even looking up objects through their
  handles, so safe. Plus the getparam/getcaps ioctl, also both safe.

- qxl only has qxl_execbuffer_ioctl, which calls into
  qxl_process_single_command. There's a lovely comment before the
  __copy_from_user_inatomic that the slowpath should be copied from
  i915, but I guess that never happened. Try not to be unlucky and get
  your CS data evicted between when it's written and the kernel tries
  to read it. The only other copy_from_user is for relocs, but those
  are done before qxl_release_reserve_list(), which seems to be the
  only thing reserving buffers (in the ttm/dma_resv sense) in that
  code. So looks safe.

- A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in
  usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this
  everywhere and needs to be fixed up.

v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a
dma_resv lock of a different object already. Christian mentioned that
ttm core does this too for ghost objects. intel-gfx-ci highlighted
that i915 has similar issues.

Unfortunately we can't do this in the usual module init functions,
because kernel threads don't have an ->mm - we have to wait around for
some user thread to do this.

Solution is to spawn a worker (but only once). It's horrible, but it
works.

v3: We can allocate mm! (Chris). Horrible worker hack out, clean
initcall solution in.

v4: Annotate with __init (Rob Herring)

Cc: Rob Herring <robh@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 drivers/dma-buf/dma-resv.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

Comments

Daniel Vetter Nov. 4, 2019, 5:48 p.m. UTC | #1
On Mon, Nov 04, 2019 at 06:37:59PM +0100, Daniel Vetter wrote:
> Full audit of everyone:
> 
> - i915, radeon, amdgpu should be clean per their maintainers.
> 
> - vram helpers should be fine, they don't do command submission, so
>   really no business holding struct_mutex while doing copy_*_user. But
>   I haven't checked them all.
> 
> - panfrost seems to dma_resv_lock only in panfrost_job_push, which
>   looks clean.
> 
> - v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(),
>   copying from/to userspace happens all in v3d_lookup_bos which is
>   outside of the critical section.
> 
> - vmwgfx has a bunch of ioctls that do their own copy_*_user:
>   - vmw_execbuf_process: First this does some copies in
>     vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself.
>     Then comes the usual ttm reserve/validate sequence, then actual
>     submission/fencing, then unreserving, and finally some more
>     copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of
>     details, but looks all safe.
>   - vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be
>     seen, seems to only create a fence and copy it out.
>   - a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be
>     found there.
>   Summary: vmwgfx seems to be fine too.
> 
> - virtio: There's virtio_gpu_execbuffer_ioctl, which does all the
>   copying from userspace before even looking up objects through their
>   handles, so safe. Plus the getparam/getcaps ioctl, also both safe.
> 
> - qxl only has qxl_execbuffer_ioctl, which calls into
>   qxl_process_single_command. There's a lovely comment before the
>   __copy_from_user_inatomic that the slowpath should be copied from
>   i915, but I guess that never happened. Try not to be unlucky and get
>   your CS data evicted between when it's written and the kernel tries
>   to read it. The only other copy_from_user is for relocs, but those
>   are done before qxl_release_reserve_list(), which seems to be the
>   only thing reserving buffers (in the ttm/dma_resv sense) in that
>   code. So looks safe.
> 
> - A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in
>   usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this
>   everywhere and needs to be fixed up.
> 
> v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a
> dma_resv lock of a different object already. Christian mentioned that
> ttm core does this too for ghost objects. intel-gfx-ci highlighted
> that i915 has similar issues.
> 
> Unfortunately we can't do this in the usual module init functions,
> because kernel threads don't have an ->mm - we have to wait around for
> some user thread to do this.
> 
> Solution is to spawn a worker (but only once). It's horrible, but it
> works.
> 
> v3: We can allocate mm! (Chris). Horrible worker hack out, clean
> initcall solution in.
> 
> v4: Annotate with __init (Rob Herring)
> 
> Cc: Rob Herring <robh@kernel.org>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> Cc: Eric Anholt <eric@anholt.net>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Ben Skeggs <bskeggs@redhat.com>
> Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
> Cc: Thomas Hellstrom <thellstrom@vmware.com>
> Reviewed-by: Christian König <christian.koenig@amd.com>
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

I lost the r-b from Thomas on the last round:

Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
> ---
>  drivers/dma-buf/dma-resv.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index 709002515550..a05ff542be22 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -34,6 +34,7 @@
>  
>  #include <linux/dma-resv.h>
>  #include <linux/export.h>
> +#include <linux/sched/mm.h>
>  
>  /**
>   * DOC: Reservation Object Overview
> @@ -95,6 +96,29 @@ static void dma_resv_list_free(struct dma_resv_list *list)
>  	kfree_rcu(list, rcu);
>  }
>  
> +#if IS_ENABLED(CONFIG_LOCKDEP)
> +static void __init dma_resv_lockdep(void)
> +{
> +	struct mm_struct *mm = mm_alloc();
> +	struct dma_resv obj;
> +
> +	if (!mm)
> +		return;
> +
> +	dma_resv_init(&obj);
> +
> +	down_read(&mm->mmap_sem);
> +	ww_mutex_lock(&obj.lock, NULL);
> +	fs_reclaim_acquire(GFP_KERNEL);
> +	fs_reclaim_release(GFP_KERNEL);
> +	ww_mutex_unlock(&obj.lock);
> +	up_read(&mm->mmap_sem);
> +	
> +	mmput(mm);
> +}
> +subsys_initcall(dma_resv_lockdep);
> +#endif
> +
>  /**
>   * dma_resv_init - initialize a reservation object
>   * @obj: the reservation object
> -- 
> 2.24.0.rc2
>
Christian König Nov. 4, 2019, 8:01 p.m. UTC | #2
Am 04.11.19 um 18:37 schrieb Daniel Vetter:
> Full audit of everyone:
>
> - i915, radeon, amdgpu should be clean per their maintainers.
>
> - vram helpers should be fine, they don't do command submission, so
>    really no business holding struct_mutex while doing copy_*_user. But
>    I haven't checked them all.
>
> - panfrost seems to dma_resv_lock only in panfrost_job_push, which
>    looks clean.
>
> - v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(),
>    copying from/to userspace happens all in v3d_lookup_bos which is
>    outside of the critical section.
>
> - vmwgfx has a bunch of ioctls that do their own copy_*_user:
>    - vmw_execbuf_process: First this does some copies in
>      vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself.
>      Then comes the usual ttm reserve/validate sequence, then actual
>      submission/fencing, then unreserving, and finally some more
>      copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of
>      details, but looks all safe.
>    - vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be
>      seen, seems to only create a fence and copy it out.
>    - a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be
>      found there.
>    Summary: vmwgfx seems to be fine too.
>
> - virtio: There's virtio_gpu_execbuffer_ioctl, which does all the
>    copying from userspace before even looking up objects through their
>    handles, so safe. Plus the getparam/getcaps ioctl, also both safe.
>
> - qxl only has qxl_execbuffer_ioctl, which calls into
>    qxl_process_single_command. There's a lovely comment before the
>    __copy_from_user_inatomic that the slowpath should be copied from
>    i915, but I guess that never happened. Try not to be unlucky and get
>    your CS data evicted between when it's written and the kernel tries
>    to read it. The only other copy_from_user is for relocs, but those
>    are done before qxl_release_reserve_list(), which seems to be the
>    only thing reserving buffers (in the ttm/dma_resv sense) in that
>    code. So looks safe.
>
> - A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in
>    usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this
>    everywhere and needs to be fixed up.
>
> v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a
> dma_resv lock of a different object already. Christian mentioned that
> ttm core does this too for ghost objects. intel-gfx-ci highlighted
> that i915 has similar issues.
>
> Unfortunately we can't do this in the usual module init functions,
> because kernel threads don't have an ->mm - we have to wait around for
> some user thread to do this.
>
> Solution is to spawn a worker (but only once). It's horrible, but it
> works.
>
> v3: We can allocate mm! (Chris). Horrible worker hack out, clean
> initcall solution in.
>
> v4: Annotate with __init (Rob Herring)
>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> Cc: Eric Anholt <eric@anholt.net>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Ben Skeggs <bskeggs@redhat.com>
> Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
> Cc: Thomas Hellstrom <thellstrom@vmware.com>
> Reviewed-by: Christian König <christian.koenig@amd.com>
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

What's holding you back to commit that?

Christian.

> ---
>   drivers/dma-buf/dma-resv.c | 24 ++++++++++++++++++++++++
>   1 file changed, 24 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index 709002515550..a05ff542be22 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -34,6 +34,7 @@
>   
>   #include <linux/dma-resv.h>
>   #include <linux/export.h>
> +#include <linux/sched/mm.h>
>   
>   /**
>    * DOC: Reservation Object Overview
> @@ -95,6 +96,29 @@ static void dma_resv_list_free(struct dma_resv_list *list)
>   	kfree_rcu(list, rcu);
>   }
>   
> +#if IS_ENABLED(CONFIG_LOCKDEP)
> +static void __init dma_resv_lockdep(void)
> +{
> +	struct mm_struct *mm = mm_alloc();
> +	struct dma_resv obj;
> +
> +	if (!mm)
> +		return;
> +
> +	dma_resv_init(&obj);
> +
> +	down_read(&mm->mmap_sem);
> +	ww_mutex_lock(&obj.lock, NULL);
> +	fs_reclaim_acquire(GFP_KERNEL);
> +	fs_reclaim_release(GFP_KERNEL);
> +	ww_mutex_unlock(&obj.lock);
> +	up_read(&mm->mmap_sem);
> +	
> +	mmput(mm);
> +}
> +subsys_initcall(dma_resv_lockdep);
> +#endif
> +
>   /**
>    * dma_resv_init - initialize a reservation object
>    * @obj: the reservation object
Daniel Vetter Nov. 4, 2019, 8:55 p.m. UTC | #3
On Mon, Nov 04, 2019 at 08:01:09PM +0000, Koenig, Christian wrote:
> Am 04.11.19 um 18:37 schrieb Daniel Vetter:
> > Full audit of everyone:
> >
> > - i915, radeon, amdgpu should be clean per their maintainers.
> >
> > - vram helpers should be fine, they don't do command submission, so
> >    really no business holding struct_mutex while doing copy_*_user. But
> >    I haven't checked them all.
> >
> > - panfrost seems to dma_resv_lock only in panfrost_job_push, which
> >    looks clean.
> >
> > - v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(),
> >    copying from/to userspace happens all in v3d_lookup_bos which is
> >    outside of the critical section.
> >
> > - vmwgfx has a bunch of ioctls that do their own copy_*_user:
> >    - vmw_execbuf_process: First this does some copies in
> >      vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself.
> >      Then comes the usual ttm reserve/validate sequence, then actual
> >      submission/fencing, then unreserving, and finally some more
> >      copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of
> >      details, but looks all safe.
> >    - vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be
> >      seen, seems to only create a fence and copy it out.
> >    - a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be
> >      found there.
> >    Summary: vmwgfx seems to be fine too.
> >
> > - virtio: There's virtio_gpu_execbuffer_ioctl, which does all the
> >    copying from userspace before even looking up objects through their
> >    handles, so safe. Plus the getparam/getcaps ioctl, also both safe.
> >
> > - qxl only has qxl_execbuffer_ioctl, which calls into
> >    qxl_process_single_command. There's a lovely comment before the
> >    __copy_from_user_inatomic that the slowpath should be copied from
> >    i915, but I guess that never happened. Try not to be unlucky and get
> >    your CS data evicted between when it's written and the kernel tries
> >    to read it. The only other copy_from_user is for relocs, but those
> >    are done before qxl_release_reserve_list(), which seems to be the
> >    only thing reserving buffers (in the ttm/dma_resv sense) in that
> >    code. So looks safe.
> >
> > - A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in
> >    usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this
> >    everywhere and needs to be fixed up.
> >
> > v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a
> > dma_resv lock of a different object already. Christian mentioned that
> > ttm core does this too for ghost objects. intel-gfx-ci highlighted
> > that i915 has similar issues.
> >
> > Unfortunately we can't do this in the usual module init functions,
> > because kernel threads don't have an ->mm - we have to wait around for
> > some user thread to do this.
> >
> > Solution is to spawn a worker (but only once). It's horrible, but it
> > works.
> >
> > v3: We can allocate mm! (Chris). Horrible worker hack out, clean
> > initcall solution in.
> >
> > v4: Annotate with __init (Rob Herring)
> >
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: Alex Deucher <alexander.deucher@amd.com>
> > Cc: Christian König <christian.koenig@amd.com>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> > Cc: Eric Anholt <eric@anholt.net>
> > Cc: Dave Airlie <airlied@redhat.com>
> > Cc: Gerd Hoffmann <kraxel@redhat.com>
> > Cc: Ben Skeggs <bskeggs@redhat.com>
> > Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
> > Cc: Thomas Hellstrom <thellstrom@vmware.com>
> > Reviewed-by: Christian König <christian.koenig@amd.com>
> > Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> 
> What's holding you back to commit that?

The nouveau patch, can't push this one without also fixing nouveau :-/
-Daniel

> 
> Christian.
> 
> > ---
> >   drivers/dma-buf/dma-resv.c | 24 ++++++++++++++++++++++++
> >   1 file changed, 24 insertions(+)
> >
> > diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> > index 709002515550..a05ff542be22 100644
> > --- a/drivers/dma-buf/dma-resv.c
> > +++ b/drivers/dma-buf/dma-resv.c
> > @@ -34,6 +34,7 @@
> >   
> >   #include <linux/dma-resv.h>
> >   #include <linux/export.h>
> > +#include <linux/sched/mm.h>
> >   
> >   /**
> >    * DOC: Reservation Object Overview
> > @@ -95,6 +96,29 @@ static void dma_resv_list_free(struct dma_resv_list *list)
> >   	kfree_rcu(list, rcu);
> >   }
> >   
> > +#if IS_ENABLED(CONFIG_LOCKDEP)
> > +static void __init dma_resv_lockdep(void)
> > +{
> > +	struct mm_struct *mm = mm_alloc();
> > +	struct dma_resv obj;
> > +
> > +	if (!mm)
> > +		return;
> > +
> > +	dma_resv_init(&obj);
> > +
> > +	down_read(&mm->mmap_sem);
> > +	ww_mutex_lock(&obj.lock, NULL);
> > +	fs_reclaim_acquire(GFP_KERNEL);
> > +	fs_reclaim_release(GFP_KERNEL);
> > +	ww_mutex_unlock(&obj.lock);
> > +	up_read(&mm->mmap_sem);
> > +	
> > +	mmput(mm);
> > +}
> > +subsys_initcall(dma_resv_lockdep);
> > +#endif
> > +
> >   /**
> >    * dma_resv_init - initialize a reservation object
> >    * @obj: the reservation object
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
Steven Price Nov. 11, 2019, 1:11 p.m. UTC | #4
On 04/11/2019 17:37, Daniel Vetter wrote:
> Full audit of everyone:
> 
> - i915, radeon, amdgpu should be clean per their maintainers.
> 
> - vram helpers should be fine, they don't do command submission, so
>   really no business holding struct_mutex while doing copy_*_user. But
>   I haven't checked them all.
> 
> - panfrost seems to dma_resv_lock only in panfrost_job_push, which
>   looks clean.
> 
> - v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(),
>   copying from/to userspace happens all in v3d_lookup_bos which is
>   outside of the critical section.
> 
> - vmwgfx has a bunch of ioctls that do their own copy_*_user:
>   - vmw_execbuf_process: First this does some copies in
>     vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself.
>     Then comes the usual ttm reserve/validate sequence, then actual
>     submission/fencing, then unreserving, and finally some more
>     copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of
>     details, but looks all safe.
>   - vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be
>     seen, seems to only create a fence and copy it out.
>   - a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be
>     found there.
>   Summary: vmwgfx seems to be fine too.
> 
> - virtio: There's virtio_gpu_execbuffer_ioctl, which does all the
>   copying from userspace before even looking up objects through their
>   handles, so safe. Plus the getparam/getcaps ioctl, also both safe.
> 
> - qxl only has qxl_execbuffer_ioctl, which calls into
>   qxl_process_single_command. There's a lovely comment before the
>   __copy_from_user_inatomic that the slowpath should be copied from
>   i915, but I guess that never happened. Try not to be unlucky and get
>   your CS data evicted between when it's written and the kernel tries
>   to read it. The only other copy_from_user is for relocs, but those
>   are done before qxl_release_reserve_list(), which seems to be the
>   only thing reserving buffers (in the ttm/dma_resv sense) in that
>   code. So looks safe.
> 
> - A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in
>   usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this
>   everywhere and needs to be fixed up.
> 
> v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a
> dma_resv lock of a different object already. Christian mentioned that
> ttm core does this too for ghost objects. intel-gfx-ci highlighted
> that i915 has similar issues.
> 
> Unfortunately we can't do this in the usual module init functions,
> because kernel threads don't have an ->mm - we have to wait around for
> some user thread to do this.
> 
> Solution is to spawn a worker (but only once). It's horrible, but it
> works.
> 
> v3: We can allocate mm! (Chris). Horrible worker hack out, clean
> initcall solution in.
> 
> v4: Annotate with __init (Rob Herring)
> 
> Cc: Rob Herring <robh@kernel.org>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> Cc: Eric Anholt <eric@anholt.net>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Ben Skeggs <bskeggs@redhat.com>
> Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
> Cc: Thomas Hellstrom <thellstrom@vmware.com>
> Reviewed-by: Christian König <christian.koenig@amd.com>
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
>  drivers/dma-buf/dma-resv.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index 709002515550..a05ff542be22 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -34,6 +34,7 @@
>  
>  #include <linux/dma-resv.h>
>  #include <linux/export.h>
> +#include <linux/sched/mm.h>
>  
>  /**
>   * DOC: Reservation Object Overview
> @@ -95,6 +96,29 @@ static void dma_resv_list_free(struct dma_resv_list *list)
>  	kfree_rcu(list, rcu);
>  }
>  
> +#if IS_ENABLED(CONFIG_LOCKDEP)
> +static void __init dma_resv_lockdep(void)
> +{
> +	struct mm_struct *mm = mm_alloc();
> +	struct dma_resv obj;
> +
> +	if (!mm)
> +		return;
> +
> +	dma_resv_init(&obj);
> +
> +	down_read(&mm->mmap_sem);
> +	ww_mutex_lock(&obj.lock, NULL);
> +	fs_reclaim_acquire(GFP_KERNEL);
> +	fs_reclaim_release(GFP_KERNEL);
> +	ww_mutex_unlock(&obj.lock);
> +	up_read(&mm->mmap_sem);
> +	

Nit: trailing whitespace

> +	mmput(mm);
> +}
> +subsys_initcall(dma_resv_lockdep);

This expects a function returning int, but dma_resv_lockdep() is void.
Causing:

drivers/dma-buf/dma-resv.c:119:17: error: initialization of ‘initcall_t’
{aka ‘int (*)(void)’} from incompatible pointer type ‘void (*)(void)’
[-Werror=incompatible-pointer-types]
 subsys_initcall(dma_resv_lockdep);

The below fixes it for me.

Steve

----8<----
From d07ea81611ed6e4fb8cc290f42d23dbcca2da2f8 Mon Sep 17 00:00:00 2001
From: Steven Price <steven.price@arm.com>
Date: Mon, 11 Nov 2019 13:07:19 +0000
Subject: [PATCH] dma_resv: Correct return type of dma_resv_lockdep()

subsys_initcall() expects a function which returns 'int'. Fix
dma_resv_lockdep() so it returns an 'int' error code.

Fixes: b2a8116e2592 ("dma_resv: prime lockdep annotations")
Signed-off-by: Steven Price <steven.price@arm.com>
---
 drivers/dma-buf/dma-resv.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index a05ff542be22..9918a6e5cf91 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -97,13 +97,13 @@ static void dma_resv_list_free(struct dma_resv_list *list)
 }
 
 #if IS_ENABLED(CONFIG_LOCKDEP)
-static void __init dma_resv_lockdep(void)
+static int __init dma_resv_lockdep(void)
 {
 	struct mm_struct *mm = mm_alloc();
 	struct dma_resv obj;
 
 	if (!mm)
-		return;
+		return -ENOMEM;
 
 	dma_resv_init(&obj);
 
@@ -115,6 +115,8 @@ static void __init dma_resv_lockdep(void)
 	up_read(&mm->mmap_sem);
 	
 	mmput(mm);
+
+	return 0;
 }
 subsys_initcall(dma_resv_lockdep);
 #endif
Daniel Vetter Nov. 11, 2019, 3:42 p.m. UTC | #5
On Mon, Nov 11, 2019 at 2:11 PM Steven Price <steven.price@arm.com> wrote:
>
> On 04/11/2019 17:37, Daniel Vetter wrote:
> > Full audit of everyone:
> >
> > - i915, radeon, amdgpu should be clean per their maintainers.
> >
> > - vram helpers should be fine, they don't do command submission, so
> >   really no business holding struct_mutex while doing copy_*_user. But
> >   I haven't checked them all.
> >
> > - panfrost seems to dma_resv_lock only in panfrost_job_push, which
> >   looks clean.
> >
> > - v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(),
> >   copying from/to userspace happens all in v3d_lookup_bos which is
> >   outside of the critical section.
> >
> > - vmwgfx has a bunch of ioctls that do their own copy_*_user:
> >   - vmw_execbuf_process: First this does some copies in
> >     vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself.
> >     Then comes the usual ttm reserve/validate sequence, then actual
> >     submission/fencing, then unreserving, and finally some more
> >     copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of
> >     details, but looks all safe.
> >   - vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be
> >     seen, seems to only create a fence and copy it out.
> >   - a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be
> >     found there.
> >   Summary: vmwgfx seems to be fine too.
> >
> > - virtio: There's virtio_gpu_execbuffer_ioctl, which does all the
> >   copying from userspace before even looking up objects through their
> >   handles, so safe. Plus the getparam/getcaps ioctl, also both safe.
> >
> > - qxl only has qxl_execbuffer_ioctl, which calls into
> >   qxl_process_single_command. There's a lovely comment before the
> >   __copy_from_user_inatomic that the slowpath should be copied from
> >   i915, but I guess that never happened. Try not to be unlucky and get
> >   your CS data evicted between when it's written and the kernel tries
> >   to read it. The only other copy_from_user is for relocs, but those
> >   are done before qxl_release_reserve_list(), which seems to be the
> >   only thing reserving buffers (in the ttm/dma_resv sense) in that
> >   code. So looks safe.
> >
> > - A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in
> >   usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this
> >   everywhere and needs to be fixed up.
> >
> > v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a
> > dma_resv lock of a different object already. Christian mentioned that
> > ttm core does this too for ghost objects. intel-gfx-ci highlighted
> > that i915 has similar issues.
> >
> > Unfortunately we can't do this in the usual module init functions,
> > because kernel threads don't have an ->mm - we have to wait around for
> > some user thread to do this.
> >
> > Solution is to spawn a worker (but only once). It's horrible, but it
> > works.
> >
> > v3: We can allocate mm! (Chris). Horrible worker hack out, clean
> > initcall solution in.
> >
> > v4: Annotate with __init (Rob Herring)
> >
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: Alex Deucher <alexander.deucher@amd.com>
> > Cc: Christian König <christian.koenig@amd.com>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> > Cc: Eric Anholt <eric@anholt.net>
> > Cc: Dave Airlie <airlied@redhat.com>
> > Cc: Gerd Hoffmann <kraxel@redhat.com>
> > Cc: Ben Skeggs <bskeggs@redhat.com>
> > Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
> > Cc: Thomas Hellstrom <thellstrom@vmware.com>
> > Reviewed-by: Christian König <christian.koenig@amd.com>
> > Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > ---
> >  drivers/dma-buf/dma-resv.c | 24 ++++++++++++++++++++++++
> >  1 file changed, 24 insertions(+)
> >
> > diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> > index 709002515550..a05ff542be22 100644
> > --- a/drivers/dma-buf/dma-resv.c
> > +++ b/drivers/dma-buf/dma-resv.c
> > @@ -34,6 +34,7 @@
> >
> >  #include <linux/dma-resv.h>
> >  #include <linux/export.h>
> > +#include <linux/sched/mm.h>
> >
> >  /**
> >   * DOC: Reservation Object Overview
> > @@ -95,6 +96,29 @@ static void dma_resv_list_free(struct dma_resv_list *list)
> >       kfree_rcu(list, rcu);
> >  }
> >
> > +#if IS_ENABLED(CONFIG_LOCKDEP)
> > +static void __init dma_resv_lockdep(void)
> > +{
> > +     struct mm_struct *mm = mm_alloc();
> > +     struct dma_resv obj;
> > +
> > +     if (!mm)
> > +             return;
> > +
> > +     dma_resv_init(&obj);
> > +
> > +     down_read(&mm->mmap_sem);
> > +     ww_mutex_lock(&obj.lock, NULL);
> > +     fs_reclaim_acquire(GFP_KERNEL);
> > +     fs_reclaim_release(GFP_KERNEL);
> > +     ww_mutex_unlock(&obj.lock);
> > +     up_read(&mm->mmap_sem);
> > +
>
> Nit: trailing whitespace
>
> > +     mmput(mm);
> > +}
> > +subsys_initcall(dma_resv_lockdep);
>
> This expects a function returning int, but dma_resv_lockdep() is void.
> Causing:
>
> drivers/dma-buf/dma-resv.c:119:17: error: initialization of ‘initcall_t’
> {aka ‘int (*)(void)’} from incompatible pointer type ‘void (*)(void)’
> [-Werror=incompatible-pointer-types]
>  subsys_initcall(dma_resv_lockdep);
>
> The below fixes it for me.

Uh, so _that_ was what the 0day thing was all about, I totally misread
that completely. Thanks for the patch.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Aside, do you need commit rights for pushing this kind of stuff?
-Daniel

>
> Steve
>
> ----8<----
> From d07ea81611ed6e4fb8cc290f42d23dbcca2da2f8 Mon Sep 17 00:00:00 2001
> From: Steven Price <steven.price@arm.com>
> Date: Mon, 11 Nov 2019 13:07:19 +0000
> Subject: [PATCH] dma_resv: Correct return type of dma_resv_lockdep()
>
> subsys_initcall() expects a function which returns 'int'. Fix
> dma_resv_lockdep() so it returns an 'int' error code.
>
> Fixes: b2a8116e2592 ("dma_resv: prime lockdep annotations")
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
>  drivers/dma-buf/dma-resv.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index a05ff542be22..9918a6e5cf91 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -97,13 +97,13 @@ static void dma_resv_list_free(struct dma_resv_list *list)
>  }
>
>  #if IS_ENABLED(CONFIG_LOCKDEP)
> -static void __init dma_resv_lockdep(void)
> +static int __init dma_resv_lockdep(void)
>  {
>         struct mm_struct *mm = mm_alloc();
>         struct dma_resv obj;
>
>         if (!mm)
> -               return;
> +               return -ENOMEM;
>
>         dma_resv_init(&obj);
>
> @@ -115,6 +115,8 @@ static void __init dma_resv_lockdep(void)
>         up_read(&mm->mmap_sem);
>
>         mmput(mm);
> +
> +       return 0;
>  }
>  subsys_initcall(dma_resv_lockdep);
>  #endif
> --
> 2.20.1
>
Steven Price Nov. 14, 2019, 11:50 a.m. UTC | #6
On 11/11/2019 15:42, Daniel Vetter wrote:
> On Mon, Nov 11, 2019 at 2:11 PM Steven Price <steven.price@arm.com> wrote:
>>
>> On 04/11/2019 17:37, Daniel Vetter wrote:
>>> Full audit of everyone:
>>>
>>> - i915, radeon, amdgpu should be clean per their maintainers.
>>>
>>> - vram helpers should be fine, they don't do command submission, so
>>>   really no business holding struct_mutex while doing copy_*_user. But
>>>   I haven't checked them all.
>>>
>>> - panfrost seems to dma_resv_lock only in panfrost_job_push, which
>>>   looks clean.
>>>
>>> - v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(),
>>>   copying from/to userspace happens all in v3d_lookup_bos which is
>>>   outside of the critical section.
>>>
>>> - vmwgfx has a bunch of ioctls that do their own copy_*_user:
>>>   - vmw_execbuf_process: First this does some copies in
>>>     vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself.
>>>     Then comes the usual ttm reserve/validate sequence, then actual
>>>     submission/fencing, then unreserving, and finally some more
>>>     copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of
>>>     details, but looks all safe.
>>>   - vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be
>>>     seen, seems to only create a fence and copy it out.
>>>   - a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be
>>>     found there.
>>>   Summary: vmwgfx seems to be fine too.
>>>
>>> - virtio: There's virtio_gpu_execbuffer_ioctl, which does all the
>>>   copying from userspace before even looking up objects through their
>>>   handles, so safe. Plus the getparam/getcaps ioctl, also both safe.
>>>
>>> - qxl only has qxl_execbuffer_ioctl, which calls into
>>>   qxl_process_single_command. There's a lovely comment before the
>>>   __copy_from_user_inatomic that the slowpath should be copied from
>>>   i915, but I guess that never happened. Try not to be unlucky and get
>>>   your CS data evicted between when it's written and the kernel tries
>>>   to read it. The only other copy_from_user is for relocs, but those
>>>   are done before qxl_release_reserve_list(), which seems to be the
>>>   only thing reserving buffers (in the ttm/dma_resv sense) in that
>>>   code. So looks safe.
>>>
>>> - A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in
>>>   usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this
>>>   everywhere and needs to be fixed up.
>>>
>>> v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a
>>> dma_resv lock of a different object already. Christian mentioned that
>>> ttm core does this too for ghost objects. intel-gfx-ci highlighted
>>> that i915 has similar issues.
>>>
>>> Unfortunately we can't do this in the usual module init functions,
>>> because kernel threads don't have an ->mm - we have to wait around for
>>> some user thread to do this.
>>>
>>> Solution is to spawn a worker (but only once). It's horrible, but it
>>> works.
>>>
>>> v3: We can allocate mm! (Chris). Horrible worker hack out, clean
>>> initcall solution in.
>>>
>>> v4: Annotate with __init (Rob Herring)
>>>
>>> Cc: Rob Herring <robh@kernel.org>
>>> Cc: Alex Deucher <alexander.deucher@amd.com>
>>> Cc: Christian König <christian.koenig@amd.com>
>>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>>> Cc: Rob Herring <robh@kernel.org>
>>> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
>>> Cc: Eric Anholt <eric@anholt.net>
>>> Cc: Dave Airlie <airlied@redhat.com>
>>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>>> Cc: Ben Skeggs <bskeggs@redhat.com>
>>> Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
>>> Cc: Thomas Hellstrom <thellstrom@vmware.com>
>>> Reviewed-by: Christian König <christian.koenig@amd.com>
>>> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
>>> Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
>>> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
>>> ---
>>>  drivers/dma-buf/dma-resv.c | 24 ++++++++++++++++++++++++
>>>  1 file changed, 24 insertions(+)
>>>
>>> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
>>> index 709002515550..a05ff542be22 100644
>>> --- a/drivers/dma-buf/dma-resv.c
>>> +++ b/drivers/dma-buf/dma-resv.c
>>> @@ -34,6 +34,7 @@
>>>
>>>  #include <linux/dma-resv.h>
>>>  #include <linux/export.h>
>>> +#include <linux/sched/mm.h>
>>>
>>>  /**
>>>   * DOC: Reservation Object Overview
>>> @@ -95,6 +96,29 @@ static void dma_resv_list_free(struct dma_resv_list *list)
>>>       kfree_rcu(list, rcu);
>>>  }
>>>
>>> +#if IS_ENABLED(CONFIG_LOCKDEP)
>>> +static void __init dma_resv_lockdep(void)
>>> +{
>>> +     struct mm_struct *mm = mm_alloc();
>>> +     struct dma_resv obj;
>>> +
>>> +     if (!mm)
>>> +             return;
>>> +
>>> +     dma_resv_init(&obj);
>>> +
>>> +     down_read(&mm->mmap_sem);
>>> +     ww_mutex_lock(&obj.lock, NULL);
>>> +     fs_reclaim_acquire(GFP_KERNEL);
>>> +     fs_reclaim_release(GFP_KERNEL);
>>> +     ww_mutex_unlock(&obj.lock);
>>> +     up_read(&mm->mmap_sem);
>>> +
>>
>> Nit: trailing whitespace
>>
>>> +     mmput(mm);
>>> +}
>>> +subsys_initcall(dma_resv_lockdep);
>>
>> This expects a function returning int, but dma_resv_lockdep() is void.
>> Causing:
>>
>> drivers/dma-buf/dma-resv.c:119:17: error: initialization of ‘initcall_t’
>> {aka ‘int (*)(void)’} from incompatible pointer type ‘void (*)(void)’
>> [-Werror=incompatible-pointer-types]
>>  subsys_initcall(dma_resv_lockdep);
>>
>> The below fixes it for me.
> 
> Uh, so _that_ was what the 0day thing was all about, I totally misread
> that completely. Thanks for the patch.
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> Aside, do you need commit rights for pushing this kind of stuff?

I guess it's about time I got round to requesting that:

https://gitlab.freedesktop.org/freedesktop/freedesktop/issues/208

Thanks,

Steve
Daniel Vetter Nov. 20, 2019, 10:51 a.m. UTC | #7
On Thu, Nov 14, 2019 at 11:50:28AM +0000, Steven Price wrote:
> On 11/11/2019 15:42, Daniel Vetter wrote:
> > On Mon, Nov 11, 2019 at 2:11 PM Steven Price <steven.price@arm.com> wrote:
> >>
> >> On 04/11/2019 17:37, Daniel Vetter wrote:
> >>> Full audit of everyone:
> >>>
> >>> - i915, radeon, amdgpu should be clean per their maintainers.
> >>>
> >>> - vram helpers should be fine, they don't do command submission, so
> >>>   really no business holding struct_mutex while doing copy_*_user. But
> >>>   I haven't checked them all.
> >>>
> >>> - panfrost seems to dma_resv_lock only in panfrost_job_push, which
> >>>   looks clean.
> >>>
> >>> - v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(),
> >>>   copying from/to userspace happens all in v3d_lookup_bos which is
> >>>   outside of the critical section.
> >>>
> >>> - vmwgfx has a bunch of ioctls that do their own copy_*_user:
> >>>   - vmw_execbuf_process: First this does some copies in
> >>>     vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself.
> >>>     Then comes the usual ttm reserve/validate sequence, then actual
> >>>     submission/fencing, then unreserving, and finally some more
> >>>     copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of
> >>>     details, but looks all safe.
> >>>   - vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be
> >>>     seen, seems to only create a fence and copy it out.
> >>>   - a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be
> >>>     found there.
> >>>   Summary: vmwgfx seems to be fine too.
> >>>
> >>> - virtio: There's virtio_gpu_execbuffer_ioctl, which does all the
> >>>   copying from userspace before even looking up objects through their
> >>>   handles, so safe. Plus the getparam/getcaps ioctl, also both safe.
> >>>
> >>> - qxl only has qxl_execbuffer_ioctl, which calls into
> >>>   qxl_process_single_command. There's a lovely comment before the
> >>>   __copy_from_user_inatomic that the slowpath should be copied from
> >>>   i915, but I guess that never happened. Try not to be unlucky and get
> >>>   your CS data evicted between when it's written and the kernel tries
> >>>   to read it. The only other copy_from_user is for relocs, but those
> >>>   are done before qxl_release_reserve_list(), which seems to be the
> >>>   only thing reserving buffers (in the ttm/dma_resv sense) in that
> >>>   code. So looks safe.
> >>>
> >>> - A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in
> >>>   usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this
> >>>   everywhere and needs to be fixed up.
> >>>
> >>> v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a
> >>> dma_resv lock of a different object already. Christian mentioned that
> >>> ttm core does this too for ghost objects. intel-gfx-ci highlighted
> >>> that i915 has similar issues.
> >>>
> >>> Unfortunately we can't do this in the usual module init functions,
> >>> because kernel threads don't have an ->mm - we have to wait around for
> >>> some user thread to do this.
> >>>
> >>> Solution is to spawn a worker (but only once). It's horrible, but it
> >>> works.
> >>>
> >>> v3: We can allocate mm! (Chris). Horrible worker hack out, clean
> >>> initcall solution in.
> >>>
> >>> v4: Annotate with __init (Rob Herring)
> >>>
> >>> Cc: Rob Herring <robh@kernel.org>
> >>> Cc: Alex Deucher <alexander.deucher@amd.com>
> >>> Cc: Christian König <christian.koenig@amd.com>
> >>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> >>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> >>> Cc: Rob Herring <robh@kernel.org>
> >>> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> >>> Cc: Eric Anholt <eric@anholt.net>
> >>> Cc: Dave Airlie <airlied@redhat.com>
> >>> Cc: Gerd Hoffmann <kraxel@redhat.com>
> >>> Cc: Ben Skeggs <bskeggs@redhat.com>
> >>> Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
> >>> Cc: Thomas Hellstrom <thellstrom@vmware.com>
> >>> Reviewed-by: Christian König <christian.koenig@amd.com>
> >>> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> >>> Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
> >>> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> >>> ---
> >>>  drivers/dma-buf/dma-resv.c | 24 ++++++++++++++++++++++++
> >>>  1 file changed, 24 insertions(+)
> >>>
> >>> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> >>> index 709002515550..a05ff542be22 100644
> >>> --- a/drivers/dma-buf/dma-resv.c
> >>> +++ b/drivers/dma-buf/dma-resv.c
> >>> @@ -34,6 +34,7 @@
> >>>
> >>>  #include <linux/dma-resv.h>
> >>>  #include <linux/export.h>
> >>> +#include <linux/sched/mm.h>
> >>>
> >>>  /**
> >>>   * DOC: Reservation Object Overview
> >>> @@ -95,6 +96,29 @@ static void dma_resv_list_free(struct dma_resv_list *list)
> >>>       kfree_rcu(list, rcu);
> >>>  }
> >>>
> >>> +#if IS_ENABLED(CONFIG_LOCKDEP)
> >>> +static void __init dma_resv_lockdep(void)
> >>> +{
> >>> +     struct mm_struct *mm = mm_alloc();
> >>> +     struct dma_resv obj;
> >>> +
> >>> +     if (!mm)
> >>> +             return;
> >>> +
> >>> +     dma_resv_init(&obj);
> >>> +
> >>> +     down_read(&mm->mmap_sem);
> >>> +     ww_mutex_lock(&obj.lock, NULL);
> >>> +     fs_reclaim_acquire(GFP_KERNEL);
> >>> +     fs_reclaim_release(GFP_KERNEL);
> >>> +     ww_mutex_unlock(&obj.lock);
> >>> +     up_read(&mm->mmap_sem);
> >>> +
> >>
> >> Nit: trailing whitespace
> >>
> >>> +     mmput(mm);
> >>> +}
> >>> +subsys_initcall(dma_resv_lockdep);
> >>
> >> This expects a function returning int, but dma_resv_lockdep() is void.
> >> Causing:
> >>
> >> drivers/dma-buf/dma-resv.c:119:17: error: initialization of ‘initcall_t’
> >> {aka ‘int (*)(void)’} from incompatible pointer type ‘void (*)(void)’
> >> [-Werror=incompatible-pointer-types]
> >>  subsys_initcall(dma_resv_lockdep);
> >>
> >> The below fixes it for me.
> > 
> > Uh, so _that_ was what the 0day thing was all about, I totally misread
> > that completely. Thanks for the patch.
> > 
> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > 
> > Aside, do you need commit rights for pushing this kind of stuff?
> 
> I guess it's about time I got round to requesting that:
> 
> https://gitlab.freedesktop.org/freedesktop/freedesktop/issues/208

Since this seems a bit stuck in processing I went ahead and merged your
fix meanwhile.

Thanks, Daniel

Patch
diff mbox series

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 709002515550..a05ff542be22 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -34,6 +34,7 @@ 
 
 #include <linux/dma-resv.h>
 #include <linux/export.h>
+#include <linux/sched/mm.h>
 
 /**
  * DOC: Reservation Object Overview
@@ -95,6 +96,29 @@  static void dma_resv_list_free(struct dma_resv_list *list)
 	kfree_rcu(list, rcu);
 }
 
+#if IS_ENABLED(CONFIG_LOCKDEP)
+static void __init dma_resv_lockdep(void)
+{
+	struct mm_struct *mm = mm_alloc();
+	struct dma_resv obj;
+
+	if (!mm)
+		return;
+
+	dma_resv_init(&obj);
+
+	down_read(&mm->mmap_sem);
+	ww_mutex_lock(&obj.lock, NULL);
+	fs_reclaim_acquire(GFP_KERNEL);
+	fs_reclaim_release(GFP_KERNEL);
+	ww_mutex_unlock(&obj.lock);
+	up_read(&mm->mmap_sem);
+	
+	mmput(mm);
+}
+subsys_initcall(dma_resv_lockdep);
+#endif
+
 /**
  * dma_resv_init - initialize a reservation object
  * @obj: the reservation object