| Message ID | 20230816083419.41088-5-zhengqi.arch@bytedance.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | use refcount+RCU method to implement lockless slab shrink (part 1) | expand |
Am 16.08.23 um 10:34 schrieb Qi Zheng: > Currently, the synchronize_shrinkers() is only used by TTM pool. It only > requires that no shrinkers run in parallel. > > After we use RCU+refcount method to implement the lockless slab shrink, > we can not use shrinker_rwsem or synchronize_rcu() to guarantee that all > shrinker invocations have seen an update before freeing memory. > > So we introduce a new pool_shrink_rwsem to implement a private > synchronize_shrinkers(), so as to achieve the same purpose. > > Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> > Reviewed-by: Muchun Song <songmuchun@bytedance.com> > --- > drivers/gpu/drm/ttm/ttm_pool.c | 15 +++++++++++++++ > include/linux/shrinker.h | 1 - > mm/shrinker.c | 15 --------------- > 3 files changed, 15 insertions(+), 16 deletions(-) > > diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c > index cddb9151d20f..713b1c0a70e1 100644 > --- a/drivers/gpu/drm/ttm/ttm_pool.c > +++ b/drivers/gpu/drm/ttm/ttm_pool.c > @@ -74,6 +74,7 @@ static struct ttm_pool_type global_dma32_uncached[MAX_ORDER + 1]; > static spinlock_t shrinker_lock; > static struct list_head shrinker_list; > static struct shrinker mm_shrinker; > +static DECLARE_RWSEM(pool_shrink_rwsem); > > /* Allocate pages of size 1 << order with the given gfp_flags */ > static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t gfp_flags, > @@ -317,6 +318,7 @@ static unsigned int ttm_pool_shrink(void) > unsigned int num_pages; > struct page *p; > > + down_read(&pool_shrink_rwsem); > spin_lock(&shrinker_lock); > pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list); > list_move_tail(&pt->shrinker_list, &shrinker_list); > @@ -329,6 +331,7 @@ static unsigned int ttm_pool_shrink(void) > } else { > num_pages = 0; > } > + up_read(&pool_shrink_rwsem); > > return num_pages; > } > @@ -572,6 +575,18 @@ void ttm_pool_init(struct ttm_pool *pool, struct device *dev, > } > EXPORT_SYMBOL(ttm_pool_init); > > +/** > + * synchronize_shrinkers - Wait for all running shrinkers to complete. > + * > + * This is useful to guarantee that all shrinker invocations have seen an > + * update, before freeing memory, similar to rcu. > + */ > +static void synchronize_shrinkers(void) Please rename that function to ttm_pool_synchronize_shrinkers(). With that done feel free to add Reviewed-by: Christian König <christian.koenig@amd.com> Regards, Christian. > +{ > + down_write(&pool_shrink_rwsem); > + up_write(&pool_shrink_rwsem); > +} > + > /** > * ttm_pool_fini - Cleanup a pool > * > diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h > index 8dc15aa37410..6b5843c3b827 100644 > --- a/include/linux/shrinker.h > +++ b/include/linux/shrinker.h > @@ -103,7 +103,6 @@ extern int __printf(2, 3) register_shrinker(struct shrinker *shrinker, > const char *fmt, ...); > extern void unregister_shrinker(struct shrinker *shrinker); > extern void free_prealloced_shrinker(struct shrinker *shrinker); > -extern void synchronize_shrinkers(void); > > #ifdef CONFIG_SHRINKER_DEBUG > extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker *shrinker, > diff --git a/mm/shrinker.c b/mm/shrinker.c > index 043c87ccfab4..a16cd448b924 100644 > --- a/mm/shrinker.c > +++ b/mm/shrinker.c > @@ -692,18 +692,3 @@ void unregister_shrinker(struct shrinker *shrinker) > shrinker->nr_deferred = NULL; > } > EXPORT_SYMBOL(unregister_shrinker); > - > -/** > - * synchronize_shrinkers - Wait for all running shrinkers to complete. > - * > - * This is equivalent to calling unregister_shrink() and register_shrinker(), > - * but atomically and with less overhead. This is useful to guarantee that all > - * shrinker invocations have seen an update, before freeing memory, similar to > - * rcu. > - */ > -void synchronize_shrinkers(void) > -{ > - down_write(&shrinker_rwsem); > - up_write(&shrinker_rwsem); > -} > -EXPORT_SYMBOL(synchronize_shrinkers);
Hi Christian, On 2023/8/16 17:14, Christian König wrote: > Am 16.08.23 um 10:34 schrieb Qi Zheng: >> Currently, the synchronize_shrinkers() is only used by TTM pool. It only >> requires that no shrinkers run in parallel. >> >> After we use RCU+refcount method to implement the lockless slab shrink, >> we can not use shrinker_rwsem or synchronize_rcu() to guarantee that all >> shrinker invocations have seen an update before freeing memory. >> >> So we introduce a new pool_shrink_rwsem to implement a private >> synchronize_shrinkers(), so as to achieve the same purpose. >> >> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> >> Reviewed-by: Muchun Song <songmuchun@bytedance.com> >> --- >> drivers/gpu/drm/ttm/ttm_pool.c | 15 +++++++++++++++ >> include/linux/shrinker.h | 1 - >> mm/shrinker.c | 15 --------------- >> 3 files changed, 15 insertions(+), 16 deletions(-) >> >> diff --git a/drivers/gpu/drm/ttm/ttm_pool.c >> b/drivers/gpu/drm/ttm/ttm_pool.c >> index cddb9151d20f..713b1c0a70e1 100644 >> --- a/drivers/gpu/drm/ttm/ttm_pool.c >> +++ b/drivers/gpu/drm/ttm/ttm_pool.c >> @@ -74,6 +74,7 @@ static struct ttm_pool_type >> global_dma32_uncached[MAX_ORDER + 1]; >> static spinlock_t shrinker_lock; >> static struct list_head shrinker_list; >> static struct shrinker mm_shrinker; >> +static DECLARE_RWSEM(pool_shrink_rwsem); >> /* Allocate pages of size 1 << order with the given gfp_flags */ >> static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t >> gfp_flags, >> @@ -317,6 +318,7 @@ static unsigned int ttm_pool_shrink(void) >> unsigned int num_pages; >> struct page *p; >> + down_read(&pool_shrink_rwsem); >> spin_lock(&shrinker_lock); >> pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list); >> list_move_tail(&pt->shrinker_list, &shrinker_list); >> @@ -329,6 +331,7 @@ static unsigned int ttm_pool_shrink(void) >> } else { >> num_pages = 0; >> } >> + up_read(&pool_shrink_rwsem); >> return num_pages; >> } >> @@ -572,6 +575,18 @@ void ttm_pool_init(struct ttm_pool *pool, struct >> device *dev, >> } >> EXPORT_SYMBOL(ttm_pool_init); >> +/** >> + * synchronize_shrinkers - Wait for all running shrinkers to complete. >> + * >> + * This is useful to guarantee that all shrinker invocations have >> seen an >> + * update, before freeing memory, similar to rcu. >> + */ >> +static void synchronize_shrinkers(void) > > Please rename that function to ttm_pool_synchronize_shrinkers(). OK, will do. > > With that done feel free to add Reviewed-by: Christian König > <christian.koenig@amd.com> > Thanks, Qi > Regards, > Christian. > >> +{ >> + down_write(&pool_shrink_rwsem); >> + up_write(&pool_shrink_rwsem); >> +} >> + >> /** >> * ttm_pool_fini - Cleanup a pool >> * >> diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h >> index 8dc15aa37410..6b5843c3b827 100644 >> --- a/include/linux/shrinker.h >> +++ b/include/linux/shrinker.h >> @@ -103,7 +103,6 @@ extern int __printf(2, 3) register_shrinker(struct >> shrinker *shrinker, >> const char *fmt, ...); >> extern void unregister_shrinker(struct shrinker *shrinker); >> extern void free_prealloced_shrinker(struct shrinker *shrinker); >> -extern void synchronize_shrinkers(void); >> #ifdef CONFIG_SHRINKER_DEBUG >> extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker >> *shrinker, >> diff --git a/mm/shrinker.c b/mm/shrinker.c >> index 043c87ccfab4..a16cd448b924 100644 >> --- a/mm/shrinker.c >> +++ b/mm/shrinker.c >> @@ -692,18 +692,3 @@ void unregister_shrinker(struct shrinker *shrinker) >> shrinker->nr_deferred = NULL; >> } >> EXPORT_SYMBOL(unregister_shrinker); >> - >> -/** >> - * synchronize_shrinkers - Wait for all running shrinkers to complete. >> - * >> - * This is equivalent to calling unregister_shrink() and >> register_shrinker(), >> - * but atomically and with less overhead. This is useful to guarantee >> that all >> - * shrinker invocations have seen an update, before freeing memory, >> similar to >> - * rcu. >> - */ >> -void synchronize_shrinkers(void) >> -{ >> - down_write(&shrinker_rwsem); >> - up_write(&shrinker_rwsem); >> -} >> -EXPORT_SYMBOL(synchronize_shrinkers); >
diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c index cddb9151d20f..713b1c0a70e1 100644 --- a/drivers/gpu/drm/ttm/ttm_pool.c +++ b/drivers/gpu/drm/ttm/ttm_pool.c @@ -74,6 +74,7 @@ static struct ttm_pool_type global_dma32_uncached[MAX_ORDER + 1]; static spinlock_t shrinker_lock; static struct list_head shrinker_list; static struct shrinker mm_shrinker; +static DECLARE_RWSEM(pool_shrink_rwsem); /* Allocate pages of size 1 << order with the given gfp_flags */ static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t gfp_flags, @@ -317,6 +318,7 @@ static unsigned int ttm_pool_shrink(void) unsigned int num_pages; struct page *p; + down_read(&pool_shrink_rwsem); spin_lock(&shrinker_lock); pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list); list_move_tail(&pt->shrinker_list, &shrinker_list); @@ -329,6 +331,7 @@ static unsigned int ttm_pool_shrink(void) } else { num_pages = 0; } + up_read(&pool_shrink_rwsem); return num_pages; } @@ -572,6 +575,18 @@ void ttm_pool_init(struct ttm_pool *pool, struct device *dev, } EXPORT_SYMBOL(ttm_pool_init); +/** + * synchronize_shrinkers - Wait for all running shrinkers to complete. + * + * This is useful to guarantee that all shrinker invocations have seen an + * update, before freeing memory, similar to rcu. + */ +static void synchronize_shrinkers(void) +{ + down_write(&pool_shrink_rwsem); + up_write(&pool_shrink_rwsem); +} + /** * ttm_pool_fini - Cleanup a pool * diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 8dc15aa37410..6b5843c3b827 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -103,7 +103,6 @@ extern int __printf(2, 3) register_shrinker(struct shrinker *shrinker, const char *fmt, ...); extern void unregister_shrinker(struct shrinker *shrinker); extern void free_prealloced_shrinker(struct shrinker *shrinker); -extern void synchronize_shrinkers(void); #ifdef CONFIG_SHRINKER_DEBUG extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker *shrinker, diff --git a/mm/shrinker.c b/mm/shrinker.c index 043c87ccfab4..a16cd448b924 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -692,18 +692,3 @@ void unregister_shrinker(struct shrinker *shrinker) shrinker->nr_deferred = NULL; } EXPORT_SYMBOL(unregister_shrinker); - -/** - * synchronize_shrinkers - Wait for all running shrinkers to complete. - * - * This is equivalent to calling unregister_shrink() and register_shrinker(), - * but atomically and with less overhead. This is useful to guarantee that all - * shrinker invocations have seen an update, before freeing memory, similar to - * rcu. - */ -void synchronize_shrinkers(void) -{ - down_write(&shrinker_rwsem); - up_write(&shrinker_rwsem); -} -EXPORT_SYMBOL(synchronize_shrinkers);