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memcg: replace memcg ID idr with xarray

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At the moment memcg IDs are managed through IDR which requires external
synchronization mechanisms and makes the allocation code a bit awkward. 
Let's switch to xarray and make the code simpler.

[shakeel.butt@linux.dev: fix error path in mem_cgroup_alloc(), per Dan]
  Link: https://lkml.kernel.org/r/20240815155402.3630804-1-shakeel.butt@linux.dev
Link: https://lkml.kernel.org/r/20240809172618.2946790-1-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Shakeel Butt 2024-08-09 10:26:18 -07:00 committed by Andrew Morton
parent 072cd213b7
commit 0722237191
1 changed files with 10 additions and 29 deletions
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39
mm/memcontrol.c
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@ -3363,29 +3363,12 @@ static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
*/
#define MEM_CGROUP_ID_MAX ((1UL << MEM_CGROUP_ID_SHIFT) - 1)
static DEFINE_IDR(mem_cgroup_idr);
static DEFINE_SPINLOCK(memcg_idr_lock);
static int mem_cgroup_alloc_id(void)
{
int ret;
idr_preload(GFP_KERNEL);
spin_lock(&memcg_idr_lock);
ret = idr_alloc(&mem_cgroup_idr, NULL, 1, MEM_CGROUP_ID_MAX + 1,
GFP_NOWAIT);
spin_unlock(&memcg_idr_lock);
idr_preload_end();
return ret;
}
static DEFINE_XARRAY_ALLOC1(mem_cgroup_ids);
static void mem_cgroup_id_remove(struct mem_cgroup *memcg)
{
if (memcg->id.id > 0) {
spin_lock(&memcg_idr_lock);
idr_remove(&mem_cgroup_idr, memcg->id.id);
spin_unlock(&memcg_idr_lock);
xa_erase(&mem_cgroup_ids, memcg->id.id);
memcg->id.id = 0;
}
}
@ -3420,7 +3403,7 @@ static inline void mem_cgroup_id_put(struct mem_cgroup *memcg)
struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
{
WARN_ON_ONCE(!rcu_read_lock_held());
return idr_find(&mem_cgroup_idr, id);
return xa_load(&mem_cgroup_ids, id);
}
#ifdef CONFIG_SHRINKER_DEBUG
@ -3513,17 +3496,17 @@ static struct mem_cgroup *mem_cgroup_alloc(struct mem_cgroup *parent)
struct mem_cgroup *memcg;
int node, cpu;
int __maybe_unused i;
long error = -ENOMEM;
long error;
memcg = kzalloc(struct_size(memcg, nodeinfo, nr_node_ids), GFP_KERNEL);
if (!memcg)
return ERR_PTR(error);
return ERR_PTR(-ENOMEM);
memcg->id.id = mem_cgroup_alloc_id();
if (memcg->id.id < 0) {
error = memcg->id.id;
error = xa_alloc(&mem_cgroup_ids, &memcg->id.id, NULL,
XA_LIMIT(1, MEM_CGROUP_ID_MAX), GFP_KERNEL);
if (error)
goto fail;
}
error = -ENOMEM;
memcg->vmstats = kzalloc(sizeof(struct memcg_vmstats),
GFP_KERNEL_ACCOUNT);
@ -3664,9 +3647,7 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
* publish it here at the end of onlining. This matches the
* regular ID destruction during offlining.
*/
spin_lock(&memcg_idr_lock);
idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
spin_unlock(&memcg_idr_lock);
xa_store(&mem_cgroup_ids, memcg->id.id, memcg, GFP_KERNEL);
return 0;
offline_kmem: