The patch titled
Subject: memcg: let css_get_next() rely upon rcu_read_lock()
has been added to the -mm tree. Its filename is
memcg-let-css_get_next-rely-upon-rcu_read_lock.patch
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From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: memcg: let css_get_next() rely upon rcu_read_lock()
Remove lock and unlock around css_get_next()'s call to idr_get_next().
memcg iterators (only users of css_get_next) already did rcu_read_lock(),
and its comment demands that; but add a WARN_ON_ONCE to make sure of it.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Acked-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/cgroup.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff -puN kernel/cgroup.c~memcg-let-css_get_next-rely-upon-rcu_read_lock kernel/cgroup.c
--- a/kernel/cgroup.c~memcg-let-css_get_next-rely-upon-rcu_read_lock
+++ a/kernel/cgroup.c
@@ -5087,6 +5087,8 @@ css_get_next(struct cgroup_subsys *ss, i
return NULL;
BUG_ON(!ss->use_id);
+ WARN_ON_ONCE(!rcu_read_lock_held());
+
/* fill start point for scan */
tmpid = id;
while (1) {
@@ -5094,10 +5096,7 @@ css_get_next(struct cgroup_subsys *ss, i
* scan next entry from bitmap(tree), tmpid is updated after
* idr_get_next().
*/
- spin_lock(&ss->id_lock);
tmp = idr_get_next(&ss->idr, &tmpid);
- spin_unlock(&ss->id_lock);
-
if (!tmp)
break;
if (tmp->depth >= depth && tmp->stack[depth] == rootid) {
_
Subject: Subject: memcg: let css_get_next() rely upon rcu_read_lock()
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
proc-clear_refs-do-not-clear-reserved-pages.patch
mm-memcg-update-the-correct-soft-limit-tree-during-migration.patch
shm_unlock-fix-long-unpreemptible-section.patch
shm_unlock-fix-unevictable-pages-stranded-after-swap.patch
mm-fix-rss-count-leakage-during-migration.patch
mm-add-rss-counters-consistency-check.patch
mm-postpone-migrated-page-mapping-reset.patch
memcg-replace-mem_cont-by-mem_res_ctlr.patch
memcg-replace-mem-and-mem_cont-stragglers.patch
memcg-lru_size-instead-of-mem_cgroup_zstat.patch
memcg-enum-lru_list-lru.patch
memcg-remove-redundant-returns.patch
idr-make-idr_get_next-good-for-rcu_read_lock.patch
cgroup-revert-ss_id_lock-to-spinlock.patch
memcg-let-css_get_next-rely-upon-rcu_read_lock.patch
prio_tree-debugging-patch.patch
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