Commit 475733dd authored by Kirill Tkhai's avatar Kirill Tkhai Committed by Andrew Morton

mm: vmscan: add shrinker_srcu_generation

After we make slab shrink lockless with SRCU, the longest sleep
unregister_shrinker() will be a sleep waiting for all do_shrink_slab()
calls.

To avoid long unbreakable action in the unregister_shrinker(), add
shrinker_srcu_generation to restore a check similar to the
rwsem_is_contendent() check that we had before.

And for memcg slab shrink, we unlock SRCU and continue iterations from the
next shrinker id.

Link: https://lkml.kernel.org/r/20230313112819.38938-5-zhengqi.arch@bytedance.comSigned-off-by: default avatarKirill Tkhai <tkhai@ya.ru>
Signed-off-by: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarRoman Gushchin <roman.gushchin@linux.dev>
Cc: Christian König <christian.koenig@amd.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Sultan Alsawaf <sultan@kerneltoast.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent caa05325
...@@ -204,6 +204,7 @@ static void set_task_reclaim_state(struct task_struct *task, ...@@ -204,6 +204,7 @@ static void set_task_reclaim_state(struct task_struct *task,
LIST_HEAD(shrinker_list); LIST_HEAD(shrinker_list);
DECLARE_RWSEM(shrinker_rwsem); DECLARE_RWSEM(shrinker_rwsem);
DEFINE_SRCU(shrinker_srcu); DEFINE_SRCU(shrinker_srcu);
static atomic_t shrinker_srcu_generation = ATOMIC_INIT(0);
#ifdef CONFIG_MEMCG #ifdef CONFIG_MEMCG
static int shrinker_nr_max; static int shrinker_nr_max;
...@@ -776,6 +777,7 @@ void unregister_shrinker(struct shrinker *shrinker) ...@@ -776,6 +777,7 @@ void unregister_shrinker(struct shrinker *shrinker)
debugfs_entry = shrinker_debugfs_remove(shrinker); debugfs_entry = shrinker_debugfs_remove(shrinker);
up_write(&shrinker_rwsem); up_write(&shrinker_rwsem);
atomic_inc(&shrinker_srcu_generation);
synchronize_srcu(&shrinker_srcu); synchronize_srcu(&shrinker_srcu);
debugfs_remove_recursive(debugfs_entry); debugfs_remove_recursive(debugfs_entry);
...@@ -797,6 +799,7 @@ void synchronize_shrinkers(void) ...@@ -797,6 +799,7 @@ void synchronize_shrinkers(void)
{ {
down_write(&shrinker_rwsem); down_write(&shrinker_rwsem);
up_write(&shrinker_rwsem); up_write(&shrinker_rwsem);
atomic_inc(&shrinker_srcu_generation);
synchronize_srcu(&shrinker_srcu); synchronize_srcu(&shrinker_srcu);
} }
EXPORT_SYMBOL(synchronize_shrinkers); EXPORT_SYMBOL(synchronize_shrinkers);
...@@ -906,18 +909,20 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, ...@@ -906,18 +909,20 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
{ {
struct shrinker_info *info; struct shrinker_info *info;
unsigned long ret, freed = 0; unsigned long ret, freed = 0;
int srcu_idx; int srcu_idx, generation;
int i; int i = 0;
if (!mem_cgroup_online(memcg)) if (!mem_cgroup_online(memcg))
return 0; return 0;
again:
srcu_idx = srcu_read_lock(&shrinker_srcu); srcu_idx = srcu_read_lock(&shrinker_srcu);
info = shrinker_info_srcu(memcg, nid); info = shrinker_info_srcu(memcg, nid);
if (unlikely(!info)) if (unlikely(!info))
goto unlock; goto unlock;
for_each_set_bit(i, info->map, info->map_nr_max) { generation = atomic_read(&shrinker_srcu_generation);
for_each_set_bit_from(i, info->map, info->map_nr_max) {
struct shrink_control sc = { struct shrink_control sc = {
.gfp_mask = gfp_mask, .gfp_mask = gfp_mask,
.nid = nid, .nid = nid,
...@@ -963,6 +968,11 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, ...@@ -963,6 +968,11 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
set_shrinker_bit(memcg, nid, i); set_shrinker_bit(memcg, nid, i);
} }
freed += ret; freed += ret;
if (atomic_read(&shrinker_srcu_generation) != generation) {
srcu_read_unlock(&shrinker_srcu, srcu_idx);
i++;
goto again;
}
} }
unlock: unlock:
srcu_read_unlock(&shrinker_srcu, srcu_idx); srcu_read_unlock(&shrinker_srcu, srcu_idx);
...@@ -1002,7 +1012,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, ...@@ -1002,7 +1012,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
{ {
unsigned long ret, freed = 0; unsigned long ret, freed = 0;
struct shrinker *shrinker; struct shrinker *shrinker;
int srcu_idx; int srcu_idx, generation;
/* /*
* The root memcg might be allocated even though memcg is disabled * The root memcg might be allocated even though memcg is disabled
...@@ -1016,6 +1026,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, ...@@ -1016,6 +1026,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
srcu_idx = srcu_read_lock(&shrinker_srcu); srcu_idx = srcu_read_lock(&shrinker_srcu);
generation = atomic_read(&shrinker_srcu_generation);
list_for_each_entry_srcu(shrinker, &shrinker_list, list, list_for_each_entry_srcu(shrinker, &shrinker_list, list,
srcu_read_lock_held(&shrinker_srcu)) { srcu_read_lock_held(&shrinker_srcu)) {
struct shrink_control sc = { struct shrink_control sc = {
...@@ -1028,6 +1039,11 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, ...@@ -1028,6 +1039,11 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
if (ret == SHRINK_EMPTY) if (ret == SHRINK_EMPTY)
ret = 0; ret = 0;
freed += ret; freed += ret;
if (atomic_read(&shrinker_srcu_generation) != generation) {
freed = freed ? : 1;
break;
}
} }
srcu_read_unlock(&shrinker_srcu, srcu_idx); srcu_read_unlock(&shrinker_srcu, srcu_idx);
......
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