Re: [Freedreno] [PATCH v3 06/23] drm/msm/gem: Move locking in shrinker path

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, Oct 19, 2020 at 10:45 PM Rob Clark <robdclark@xxxxxxxxx> wrote:
>
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> Move grabbing the bo lock into shrinker, with a msm_gem_trylock() to
> skip over bo's that are already locked.  This gets rid of the nested
> lock classes.
>
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/msm_gem.c          | 24 +++++----------------
>  drivers/gpu/drm/msm/msm_gem.h          | 29 ++++++++++----------------
>  drivers/gpu/drm/msm/msm_gem_shrinker.c | 27 +++++++++++++++++-------
>  3 files changed, 35 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
> index e0d8d739b068..1195847714ba 100644
> --- a/drivers/gpu/drm/msm/msm_gem.c
> +++ b/drivers/gpu/drm/msm/msm_gem.c
> @@ -17,8 +17,6 @@
>  #include "msm_gpu.h"
>  #include "msm_mmu.h"
>
> -static void msm_gem_vunmap_locked(struct drm_gem_object *obj);
> -
>
>  static dma_addr_t physaddr(struct drm_gem_object *obj)
>  {
> @@ -693,20 +691,19 @@ int msm_gem_madvise(struct drm_gem_object *obj, unsigned madv)
>         return (madv != __MSM_MADV_PURGED);
>  }
>
> -void msm_gem_purge(struct drm_gem_object *obj, enum msm_gem_lock subclass)
> +void msm_gem_purge(struct drm_gem_object *obj)
>  {
>         struct drm_device *dev = obj->dev;
>         struct msm_gem_object *msm_obj = to_msm_bo(obj);
>
>         WARN_ON(!mutex_is_locked(&dev->struct_mutex));
> +       WARN_ON(!msm_gem_is_locked(obj));
>         WARN_ON(!is_purgeable(msm_obj));
>         WARN_ON(obj->import_attach);
>
> -       mutex_lock_nested(&msm_obj->lock, subclass);
> -
>         put_iova(obj);
>
> -       msm_gem_vunmap_locked(obj);
> +       msm_gem_vunmap(obj);
>
>         put_pages(obj);
>
> @@ -724,11 +721,9 @@ void msm_gem_purge(struct drm_gem_object *obj, enum msm_gem_lock subclass)
>
>         invalidate_mapping_pages(file_inode(obj->filp)->i_mapping,
>                         0, (loff_t)-1);
> -
> -       msm_gem_unlock(obj);
>  }
>
> -static void msm_gem_vunmap_locked(struct drm_gem_object *obj)
> +void msm_gem_vunmap(struct drm_gem_object *obj)
>  {
>         struct msm_gem_object *msm_obj = to_msm_bo(obj);
>
> @@ -741,15 +736,6 @@ static void msm_gem_vunmap_locked(struct drm_gem_object *obj)
>         msm_obj->vaddr = NULL;
>  }
>
> -void msm_gem_vunmap(struct drm_gem_object *obj, enum msm_gem_lock subclass)
> -{
> -       struct msm_gem_object *msm_obj = to_msm_bo(obj);
> -
> -       mutex_lock_nested(&msm_obj->lock, subclass);
> -       msm_gem_vunmap_locked(obj);
> -       msm_gem_unlock(obj);
> -}
> -
>  /* must be called before _move_to_active().. */
>  int msm_gem_sync_object(struct drm_gem_object *obj,
>                 struct msm_fence_context *fctx, bool exclusive)
> @@ -986,7 +972,7 @@ static void free_object(struct msm_gem_object *msm_obj)
>
>                 drm_prime_gem_destroy(obj, msm_obj->sgt);
>         } else {
> -               msm_gem_vunmap_locked(obj);
> +               msm_gem_vunmap(obj);
>                 put_pages(obj);
>         }
>
> diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
> index d55d5401a2d2..c5232b8da794 100644
> --- a/drivers/gpu/drm/msm/msm_gem.h
> +++ b/drivers/gpu/drm/msm/msm_gem.h
> @@ -162,6 +162,13 @@ msm_gem_lock(struct drm_gem_object *obj)
>         mutex_lock(&msm_obj->lock);
>  }
>
> +static inline bool __must_check
> +msm_gem_trylock(struct drm_gem_object *obj)
> +{
> +       struct msm_gem_object *msm_obj = to_msm_bo(obj);
> +       return mutex_trylock_recursive(&msm_obj->lock) == MUTEX_TRYLOCK_SUCCESS;

This can just be

    return mutex_trylock(&msm_obj->lock) == 1;

now, right?

> +}
> +
>  static inline int
>  msm_gem_lock_interruptible(struct drm_gem_object *obj)
>  {
> @@ -190,6 +197,7 @@ static inline bool is_active(struct msm_gem_object *msm_obj)
>
>  static inline bool is_purgeable(struct msm_gem_object *msm_obj)
>  {
> +       WARN_ON(!msm_gem_is_locked(&msm_obj->base));
>         WARN_ON(!mutex_is_locked(&msm_obj->base.dev->struct_mutex));
>         return (msm_obj->madv == MSM_MADV_DONTNEED) && msm_obj->sgt &&
>                         !msm_obj->base.dma_buf && !msm_obj->base.import_attach;
> @@ -197,27 +205,12 @@ static inline bool is_purgeable(struct msm_gem_object *msm_obj)
>
>  static inline bool is_vunmapable(struct msm_gem_object *msm_obj)
>  {
> +       WARN_ON(!msm_gem_is_locked(&msm_obj->base));
>         return (msm_obj->vmap_count == 0) && msm_obj->vaddr;
>  }
>
> -/* The shrinker can be triggered while we hold objA->lock, and need
> - * to grab objB->lock to purge it.  Lockdep just sees these as a single
> - * class of lock, so we use subclasses to teach it the difference.
> - *
> - * OBJ_LOCK_NORMAL is implicit (ie. normal mutex_lock() call), and
> - * OBJ_LOCK_SHRINKER is used by shrinker.
> - *
> - * It is *essential* that we never go down paths that could trigger the
> - * shrinker for a purgable object.  This is ensured by checking that
> - * msm_obj->madv == MSM_MADV_WILLNEED.
> - */
> -enum msm_gem_lock {
> -       OBJ_LOCK_NORMAL,
> -       OBJ_LOCK_SHRINKER,
> -};
> -
> -void msm_gem_purge(struct drm_gem_object *obj, enum msm_gem_lock subclass);
> -void msm_gem_vunmap(struct drm_gem_object *obj, enum msm_gem_lock subclass);
> +void msm_gem_purge(struct drm_gem_object *obj);
> +void msm_gem_vunmap(struct drm_gem_object *obj);
>  void msm_gem_free_work(struct work_struct *work);
>
>  /* Created per submit-ioctl, to track bo's and cmdstream bufs, etc,
> diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c
> index 482576d7a39a..2dc0ffa925b4 100644
> --- a/drivers/gpu/drm/msm/msm_gem_shrinker.c
> +++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c
> @@ -52,8 +52,11 @@ msm_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
>                 return 0;
>
>         list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) {
> +               if (!msm_gem_trylock(&msm_obj->base))
> +                       continue;
>                 if (is_purgeable(msm_obj))
>                         count += msm_obj->base.size >> PAGE_SHIFT;
> +               msm_gem_unlock(&msm_obj->base);
>         }
>
>         if (unlock)
> @@ -78,10 +81,13 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
>         list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) {
>                 if (freed >= sc->nr_to_scan)
>                         break;
> +               if (!msm_gem_trylock(&msm_obj->base))
> +                       continue;
>                 if (is_purgeable(msm_obj)) {
> -                       msm_gem_purge(&msm_obj->base, OBJ_LOCK_SHRINKER);
> +                       msm_gem_purge(&msm_obj->base);
>                         freed += msm_obj->base.size >> PAGE_SHIFT;
>                 }
> +               msm_gem_unlock(&msm_obj->base);
>         }
>
>         if (unlock)
> @@ -107,15 +113,20 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
>                 return NOTIFY_DONE;
>
>         list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) {
> +               if (!msm_gem_trylock(&msm_obj->base))
> +                       continue;
>                 if (is_vunmapable(msm_obj)) {
> -                       msm_gem_vunmap(&msm_obj->base, OBJ_LOCK_SHRINKER);
> -                       /* since we don't know any better, lets bail after a few
> -                        * and if necessary the shrinker will be invoked again.
> -                        * Seems better than unmapping *everything*
> -                        */
> -                       if (++unmapped >= 15)
> -                               break;
> +                       msm_gem_vunmap(&msm_obj->base);
> +                       unmapped++;
>                 }
> +               msm_gem_unlock(&msm_obj->base);
> +
> +               /* since we don't know any better, lets bail after a few
> +                * and if necessary the shrinker will be invoked again.
> +                * Seems better than unmapping *everything*
> +                */
> +               if (++unmapped >= 15)
> +                       break;
>         }
>
>         if (unlock)
> --
> 2.26.2
>
> _______________________________________________
> Freedreno mailing list
> Freedreno@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/freedreno



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [Linux for Sparc]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux