The patch titled
Subject: mm: clean up mem_cgroup_iter()
has been added to the -mm mm-unstable branch. Its filename is
mm-clean-up-mem_cgroup_iter.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-clean-up-mem_cgroup_iter.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Kinsey Ho <kinseyho@xxxxxxxxxx>
Subject: mm: clean up mem_cgroup_iter()
Date: Tue, 27 Aug 2024 23:07:42 +0000
A clean up to make variable names more clear and to improve code
readability.
No functional change.
Link: https://lkml.kernel.org/r/20240827230753.2073580-6-kinseyho@xxxxxxxxxx
Signed-off-by: Kinsey Ho <kinseyho@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Michal Koutný <mkoutny@xxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Cc: Zefan Li <lizefan.x@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 30 +++++++++++-------------------
1 file changed, 11 insertions(+), 19 deletions(-)
--- a/mm/memcontrol.c~mm-clean-up-mem_cgroup_iter
+++ a/mm/memcontrol.c
@@ -987,8 +987,8 @@ struct mem_cgroup *mem_cgroup_iter(struc
{
struct mem_cgroup_reclaim_iter *iter;
struct cgroup_subsys_state *css;
- struct mem_cgroup *memcg = NULL;
- struct mem_cgroup *pos = NULL;
+ struct mem_cgroup *pos;
+ struct mem_cgroup *next = NULL;
if (mem_cgroup_disabled())
return NULL;
@@ -1000,10 +1000,9 @@ struct mem_cgroup *mem_cgroup_iter(struc
restart:
if (reclaim) {
int gen;
- struct mem_cgroup_per_node *mz;
+ int nid = reclaim->pgdat->node_id;
- mz = root->nodeinfo[reclaim->pgdat->node_id];
- iter = &mz->iter;
+ iter = &root->nodeinfo[nid]->iter;
gen = atomic_read(&iter->generation);
/*
@@ -1016,29 +1015,22 @@ restart:
goto out_unlock;
pos = READ_ONCE(iter->position);
- } else if (prev) {
+ } else
pos = prev;
- }
css = pos ? &pos->css : NULL;
- for (;;) {
- css = css_next_descendant_pre(css, &root->css);
- if (!css) {
- break;
- }
-
+ while ((css = css_next_descendant_pre(css, &root->css))) {
/*
* Verify the css and acquire a reference. The root
* is provided by the caller, so we know it's alive
* and kicking, and don't take an extra reference.
*/
- if (css == &root->css || css_tryget(css)) {
+ if (css == &root->css || css_tryget(css))
break;
- }
}
- memcg = mem_cgroup_from_css(css);
+ next = mem_cgroup_from_css(css);
if (reclaim) {
/*
@@ -1046,13 +1038,13 @@ restart:
* thread, so check that the value hasn't changed since we read
* it to avoid reclaiming from the same cgroup twice.
*/
- if (cmpxchg(&iter->position, pos, memcg) != pos) {
+ if (cmpxchg(&iter->position, pos, next) != pos) {
if (css && css != &root->css)
css_put(css);
goto restart;
}
- if (!memcg) {
+ if (!next) {
atomic_inc(&iter->generation);
/*
@@ -1071,7 +1063,7 @@ out_unlock:
if (prev && prev != root)
css_put(&prev->css);
- return memcg;
+ return next;
}
/**
_
Patches currently in -mm which might be from kinseyho@xxxxxxxxxx are
cgroup-clarify-css-sibling-linkage-is-protected-by-cgroup_mutex-or-rcu.patch
mm-dont-hold-css-refcnt-during-traversal.patch
mm-increment-gen-before-restarting-traversal.patch
mm-restart-if-multiple-traversals-raced.patch
mm-clean-up-mem_cgroup_iter.patch
