The patch titled
Subject: memcg: replace memcg ID idr with xarray
has been added to the -mm mm-unstable branch. Its filename is
memcg-replace-memcg-id-idr-with-xarray.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/memcg-replace-memcg-id-idr-with-xarray.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Subject: memcg: replace memcg ID idr with xarray
Date: Fri, 9 Aug 2024 10:26:18 -0700
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.
Link: https://lkml.kernel.org/r/20240809172618.2946790-1-shakeel.butt@xxxxxxxxx
Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 34 +++++++---------------------------
1 file changed, 7 insertions(+), 27 deletions(-)
--- a/mm/memcontrol.c~memcg-replace-memcg-id-idr-with-xarray
+++ a/mm/memcontrol.c
@@ -3395,29 +3395,12 @@ static void memcg_wb_domain_size_changed
*/
#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;
}
}
@@ -3452,7 +3435,7 @@ static inline void mem_cgroup_id_put(str
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
@@ -3551,11 +3534,10 @@ static struct mem_cgroup *mem_cgroup_all
if (!memcg)
return ERR_PTR(error);
- 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;
- }
memcg->vmstats = kzalloc(sizeof(struct memcg_vmstats),
GFP_KERNEL_ACCOUNT);
@@ -3696,9 +3678,7 @@ static int mem_cgroup_css_online(struct
* 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:
_
Patches currently in -mm which might be from shakeel.butt@xxxxxxxxx are
memcg-increase-the-valid-index-range-for-memcg-stats.patch
memcg-replace-memcg-id-idr-with-xarray.patch
