| Message ID | 20230827175449.1766701-13-dmitry.osipenko@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add generic memory shrinker to VirtIO-GPU and Panfrost DRM drivers | expand |
On Sun, 27 Aug 2023 20:54:38 +0300 Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote: > Add separate pages_pin_count for tracking of whether drm-shmem pages are > moveable or not. With the addition of memory shrinker support to drm-shmem, > the pages_use_count will no longer determine whether pages are hard-pinned > in memory, but whether pages exit and are soft-pinned (and could be swapped ^exist > out). The pages_pin_count > 1 will hard-pin pages in memory. > > Suggested-by: Boris Brezillon <boris.brezillon@collabora.com> > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> > --- > drivers/gpu/drm/drm_gem_shmem_helper.c | 22 +++++++++++++++++----- > include/drm/drm_gem_shmem_helper.h | 10 ++++++++++ > 2 files changed, 27 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index d545d3d227d7..1a7e5c332fd8 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -234,14 +234,22 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) > > dma_resv_assert_held(shmem->base.resv); > > + if (kref_get_unless_zero(&shmem->pages_pin_count)) > + return 0; > + > ret = drm_gem_shmem_get_pages_locked(shmem); > + if (!ret) > + kref_init(&shmem->pages_pin_count); > > return ret; > } > > -static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem) > +static void drm_gem_shmem_kref_unpin_pages(struct kref *kref) > { > - dma_resv_assert_held(shmem->base.resv); > + struct drm_gem_shmem_object *shmem; > + > + shmem = container_of(kref, struct drm_gem_shmem_object, > + pages_pin_count); > > drm_gem_shmem_put_pages_locked(shmem); > } > @@ -263,6 +271,9 @@ int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem) > > drm_WARN_ON(obj->dev, obj->import_attach); > > + if (kref_get_unless_zero(&shmem->pages_pin_count)) > + return 0; > + > ret = dma_resv_lock_interruptible(shmem->base.resv, NULL); > if (ret) > return ret; > @@ -286,9 +297,10 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem) > > drm_WARN_ON(obj->dev, obj->import_attach); > > - dma_resv_lock(shmem->base.resv, NULL); > - drm_gem_shmem_unpin_locked(shmem); > - dma_resv_unlock(shmem->base.resv); > + if (kref_put_dma_resv(&shmem->pages_pin_count, > + drm_gem_shmem_kref_unpin_pages, > + obj->resv, NULL)) > + dma_resv_unlock(obj->resv); > } > EXPORT_SYMBOL_GPL(drm_gem_shmem_unpin); > > diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h > index ec2d8b24e3cf..afb7cd671e2a 100644 > --- a/include/drm/drm_gem_shmem_helper.h > +++ b/include/drm/drm_gem_shmem_helper.h > @@ -39,6 +39,16 @@ struct drm_gem_shmem_object { > */ > unsigned int pages_use_count; > > + /** > + * @pages_pin_count: > + * > + * Reference count on the pinned pages table. > + * The pages allowed to be evicted and purged by memory > + * shrinker only when the count is zero, otherwise pages > + * are hard-pinned in memory. > + */ > + struct kref pages_pin_count; > + > /** > * @madv: State for madvise > *
On Sun, 27 Aug 2023 20:54:38 +0300 Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote: > Add separate pages_pin_count for tracking of whether drm-shmem pages are > moveable or not. With the addition of memory shrinker support to drm-shmem, > the pages_use_count will no longer determine whether pages are hard-pinned > in memory, but whether pages exit and are soft-pinned (and could be swapped > out). The pages_pin_count > 1 will hard-pin pages in memory. > > Suggested-by: Boris Brezillon <boris.brezillon@collabora.com> > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> > --- > drivers/gpu/drm/drm_gem_shmem_helper.c | 22 +++++++++++++++++----- > include/drm/drm_gem_shmem_helper.h | 10 ++++++++++ > 2 files changed, 27 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index d545d3d227d7..1a7e5c332fd8 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -234,14 +234,22 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) > > dma_resv_assert_held(shmem->base.resv); > > + if (kref_get_unless_zero(&shmem->pages_pin_count)) > + return 0; > + > ret = drm_gem_shmem_get_pages_locked(shmem); > + if (!ret) > + kref_init(&shmem->pages_pin_count); > > return ret; > } > > -static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem) > +static void drm_gem_shmem_kref_unpin_pages(struct kref *kref) > { > - dma_resv_assert_held(shmem->base.resv); > + struct drm_gem_shmem_object *shmem; > + > + shmem = container_of(kref, struct drm_gem_shmem_object, > + pages_pin_count); > > drm_gem_shmem_put_pages_locked(shmem); > } > @@ -263,6 +271,9 @@ int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem) > > drm_WARN_ON(obj->dev, obj->import_attach); > > + if (kref_get_unless_zero(&shmem->pages_pin_count)) > + return 0; > + > ret = dma_resv_lock_interruptible(shmem->base.resv, NULL); > if (ret) > return ret; > @@ -286,9 +297,10 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem) > > drm_WARN_ON(obj->dev, obj->import_attach); > > - dma_resv_lock(shmem->base.resv, NULL); > - drm_gem_shmem_unpin_locked(shmem); > - dma_resv_unlock(shmem->base.resv); > + if (kref_put_dma_resv(&shmem->pages_pin_count, > + drm_gem_shmem_kref_unpin_pages, > + obj->resv, NULL)) > + dma_resv_unlock(obj->resv); > } > EXPORT_SYMBOL_GPL(drm_gem_shmem_unpin); > > diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h > index ec2d8b24e3cf..afb7cd671e2a 100644 > --- a/include/drm/drm_gem_shmem_helper.h > +++ b/include/drm/drm_gem_shmem_helper.h > @@ -39,6 +39,16 @@ struct drm_gem_shmem_object { > */ > unsigned int pages_use_count; > > + /** > + * @pages_pin_count: > + * > + * Reference count on the pinned pages table. > + * The pages allowed to be evicted and purged by memory > + * shrinker only when the count is zero, otherwise pages > + * are hard-pinned in memory. > + */ > + struct kref pages_pin_count; I know it's tempting to use kref for the pages use/pin count, but I'm wondering if we wouldn't be better using a refcount_t, which provides overflow/underflow protection while still letting us control how we want to handle the locking for 0 <-> 1 transitions. By doing that, we avoid introducing core locking changes that might be more controversial/longer to get accepted. Besides, I suspect the resulting code (the one using a refcount_t) won't be more verbose/complicated (no release functions needed if you don't use kref_put(), which makes things closer to what we have right now). > + > /** > * @madv: State for madvise > *
On 8/28/23 14:46, Boris Brezillon wrote: > On Sun, 27 Aug 2023 20:54:38 +0300 > Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote: > >> Add separate pages_pin_count for tracking of whether drm-shmem pages are >> moveable or not. With the addition of memory shrinker support to drm-shmem, >> the pages_use_count will no longer determine whether pages are hard-pinned >> in memory, but whether pages exit and are soft-pinned (and could be swapped >> out). The pages_pin_count > 1 will hard-pin pages in memory. >> >> Suggested-by: Boris Brezillon <boris.brezillon@collabora.com> >> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> >> --- >> drivers/gpu/drm/drm_gem_shmem_helper.c | 22 +++++++++++++++++----- >> include/drm/drm_gem_shmem_helper.h | 10 ++++++++++ >> 2 files changed, 27 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c >> index d545d3d227d7..1a7e5c332fd8 100644 >> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c >> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c >> @@ -234,14 +234,22 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) >> >> dma_resv_assert_held(shmem->base.resv); >> >> + if (kref_get_unless_zero(&shmem->pages_pin_count)) >> + return 0; >> + >> ret = drm_gem_shmem_get_pages_locked(shmem); >> + if (!ret) >> + kref_init(&shmem->pages_pin_count); >> >> return ret; >> } >> >> -static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem) >> +static void drm_gem_shmem_kref_unpin_pages(struct kref *kref) >> { >> - dma_resv_assert_held(shmem->base.resv); >> + struct drm_gem_shmem_object *shmem; >> + >> + shmem = container_of(kref, struct drm_gem_shmem_object, >> + pages_pin_count); >> >> drm_gem_shmem_put_pages_locked(shmem); >> } >> @@ -263,6 +271,9 @@ int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem) >> >> drm_WARN_ON(obj->dev, obj->import_attach); >> >> + if (kref_get_unless_zero(&shmem->pages_pin_count)) >> + return 0; >> + >> ret = dma_resv_lock_interruptible(shmem->base.resv, NULL); >> if (ret) >> return ret; >> @@ -286,9 +297,10 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem) >> >> drm_WARN_ON(obj->dev, obj->import_attach); >> >> - dma_resv_lock(shmem->base.resv, NULL); >> - drm_gem_shmem_unpin_locked(shmem); >> - dma_resv_unlock(shmem->base.resv); >> + if (kref_put_dma_resv(&shmem->pages_pin_count, >> + drm_gem_shmem_kref_unpin_pages, >> + obj->resv, NULL)) >> + dma_resv_unlock(obj->resv); >> } >> EXPORT_SYMBOL_GPL(drm_gem_shmem_unpin); >> >> diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h >> index ec2d8b24e3cf..afb7cd671e2a 100644 >> --- a/include/drm/drm_gem_shmem_helper.h >> +++ b/include/drm/drm_gem_shmem_helper.h >> @@ -39,6 +39,16 @@ struct drm_gem_shmem_object { >> */ >> unsigned int pages_use_count; >> >> + /** >> + * @pages_pin_count: >> + * >> + * Reference count on the pinned pages table. >> + * The pages allowed to be evicted and purged by memory >> + * shrinker only when the count is zero, otherwise pages >> + * are hard-pinned in memory. >> + */ >> + struct kref pages_pin_count; > > I know it's tempting to use kref for the pages use/pin count, but I'm > wondering if we wouldn't be better using a refcount_t, which provides > overflow/underflow protection while still letting us control how we > want to handle the locking for 0 <-> 1 transitions. By doing that, we > avoid introducing core locking changes that might be more > controversial/longer to get accepted. Besides, I suspect the resulting > code (the one using a refcount_t) won't be more verbose/complicated (no > release functions needed if you don't use kref_put(), which makes > things closer to what we have right now). Alright, let's try to use refcount_t since Christian also doesn't like kref
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index d545d3d227d7..1a7e5c332fd8 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -234,14 +234,22 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) dma_resv_assert_held(shmem->base.resv); + if (kref_get_unless_zero(&shmem->pages_pin_count)) + return 0; + ret = drm_gem_shmem_get_pages_locked(shmem); + if (!ret) + kref_init(&shmem->pages_pin_count); return ret; } -static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem) +static void drm_gem_shmem_kref_unpin_pages(struct kref *kref) { - dma_resv_assert_held(shmem->base.resv); + struct drm_gem_shmem_object *shmem; + + shmem = container_of(kref, struct drm_gem_shmem_object, + pages_pin_count); drm_gem_shmem_put_pages_locked(shmem); } @@ -263,6 +271,9 @@ int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem) drm_WARN_ON(obj->dev, obj->import_attach); + if (kref_get_unless_zero(&shmem->pages_pin_count)) + return 0; + ret = dma_resv_lock_interruptible(shmem->base.resv, NULL); if (ret) return ret; @@ -286,9 +297,10 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem) drm_WARN_ON(obj->dev, obj->import_attach); - dma_resv_lock(shmem->base.resv, NULL); - drm_gem_shmem_unpin_locked(shmem); - dma_resv_unlock(shmem->base.resv); + if (kref_put_dma_resv(&shmem->pages_pin_count, + drm_gem_shmem_kref_unpin_pages, + obj->resv, NULL)) + dma_resv_unlock(obj->resv); } EXPORT_SYMBOL_GPL(drm_gem_shmem_unpin); diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h index ec2d8b24e3cf..afb7cd671e2a 100644 --- a/include/drm/drm_gem_shmem_helper.h +++ b/include/drm/drm_gem_shmem_helper.h @@ -39,6 +39,16 @@ struct drm_gem_shmem_object { */ unsigned int pages_use_count; + /** + * @pages_pin_count: + * + * Reference count on the pinned pages table. + * The pages allowed to be evicted and purged by memory + * shrinker only when the count is zero, otherwise pages + * are hard-pinned in memory. + */ + struct kref pages_pin_count; + /** * @madv: State for madvise *
Add separate pages_pin_count for tracking of whether drm-shmem pages are moveable or not. With the addition of memory shrinker support to drm-shmem, the pages_use_count will no longer determine whether pages are hard-pinned in memory, but whether pages exit and are soft-pinned (and could be swapped out). The pages_pin_count > 1 will hard-pin pages in memory. Suggested-by: Boris Brezillon <boris.brezillon@collabora.com> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> --- drivers/gpu/drm/drm_gem_shmem_helper.c | 22 +++++++++++++++++----- include/drm/drm_gem_shmem_helper.h | 10 ++++++++++ 2 files changed, 27 insertions(+), 5 deletions(-)