The quilt patch titled
Subject: drm/ttm: introduce pool_shrink_rwsem
has been removed from the -mm tree. Its filename was
drm-ttm-introduce-pool_shrink_rwsem.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Subject: drm/ttm: introduce pool_shrink_rwsem
Date: Mon, 11 Sep 2023 17:25:17 +0800
Currently, 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
ttm_pool_synchronize_shrinkers(), so as to achieve the same purpose.
Link: https://lkml.kernel.org/r/20230911092517.64141-5-zhengqi.arch@xxxxxxxxxxxxx
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Reviewed-by: Christian König <christian.koenig@xxxxxxx>
Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Chuck Lever <cel@xxxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Darrick J. Wong <djwong@xxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Kirill Tkhai <tkhai@xxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Steven Price <steven.price@xxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
Cc: Alasdair Kergon <agk@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Alyssa Rosenzweig <alyssa.rosenzweig@xxxxxxxxxxxxx>
Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
Cc: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Cc: Anna Schumaker <anna@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Bob Peterson <rpeterso@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Carlos Llamas <cmllamas@xxxxxxxxxx>
Cc: Chandan Babu R <chandan.babu@xxxxxxxxxx>
Cc: Chao Yu <chao@xxxxxxxxxx>
Cc: Chris Mason <clm@xxxxxx>
Cc: Coly Li <colyli@xxxxxxx>
Cc: Dai Ngo <Dai.Ngo@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Sterba <dsterba@xxxxxxxx>
Cc: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Cc: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
Cc: Huang Rui <ray.huang@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: Jeff Layton <jlayton@xxxxxxxxxx>
Cc: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Josef Bacik <josef@xxxxxxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Cc: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Nadav Amit <namit@xxxxxxxxxx>
Cc: Neil Brown <neilb@xxxxxxx>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Cc: Olga Kornievskaia <kolga@xxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Cc: Sean Paul <sean@xxxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
Cc: Tom Talpey <tom@xxxxxxxxxx>
Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
Cc: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Cc: Yue Hu <huyue2@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/ttm/ttm_pool.c | 17 ++++++++++++++++-
include/linux/shrinker.h | 1 -
mm/shrinker.c | 15 ---------------
3 files changed, 16 insertions(+), 17 deletions(-)
--- a/drivers/gpu/drm/ttm/ttm_pool.c~drm-ttm-introduce-pool_shrink_rwsem
+++ a/drivers/gpu/drm/ttm/ttm_pool.c
@@ -74,6 +74,7 @@ static struct ttm_pool_type global_dma32
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;
}
@@ -573,6 +576,18 @@ void ttm_pool_init(struct ttm_pool *pool
EXPORT_SYMBOL(ttm_pool_init);
/**
+ * ttm_pool_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 ttm_pool_synchronize_shrinkers(void)
+{
+ down_write(&pool_shrink_rwsem);
+ up_write(&pool_shrink_rwsem);
+}
+
+/**
* ttm_pool_fini - Cleanup a pool
*
* @pool: the pool to clean up
@@ -593,7 +608,7 @@ void ttm_pool_fini(struct ttm_pool *pool
/* We removed the pool types from the LRU, but we need to also make sure
* that no shrinker is concurrently freeing pages from the pool.
*/
- synchronize_shrinkers();
+ ttm_pool_synchronize_shrinkers();
}
EXPORT_SYMBOL(ttm_pool_fini);
--- a/include/linux/shrinker.h~drm-ttm-introduce-pool_shrink_rwsem
+++ a/include/linux/shrinker.h
@@ -103,7 +103,6 @@ extern int __printf(2, 3) register_shrin
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,
--- a/mm/shrinker.c~drm-ttm-introduce-pool_shrink_rwsem
+++ a/mm/shrinker.c
@@ -692,18 +692,3 @@ void unregister_shrinker(struct 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);
_
Patches currently in -mm which might be from zhengqi.arch@xxxxxxxxxxxxx are
