memcg: replace in_interrupt() by !in_task() in active_memcg()

set_active_memcg() uses in_interrupt() check to select proper storage for
cgroup: pointer on task struct or per-cpu pointer.

It isn't fully correct: obsoleted in_interrupt() includes tasks with
disabled BH.  It's better to use '!in_task()' instead.

Link: https://lkml.org/lkml/2021/7/26/487
Link: https://lkml.kernel.org/r/ed4448b0-4970-616f-7368-ef9dd3cb628d@virtuozzo.com
Fixes: 37d5985c003d ("mm: kmem: prepare remote memcg charging infra for interrupt contexts")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 8894825cc4db2897080809dd8a67d8a4b0456779..5561486fddef7a31675958319a240a9369e2bdd7 100644 (file)
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -306,7 +306,7 @@ set_active_memcg(struct mem_cgroup *memcg)
 {
        struct mem_cgroup *old;
 
-       if (in_interrupt()) {
+       if (!in_task()) {
                old = this_cpu_read(int_active_memcg);
                this_cpu_write(int_active_memcg, memcg);
        } else {

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4d8c9afecf98572b1cf557896ce0346911b1c907..b09f2639f28b1c25a3e2178c495c7bf2d337afd4 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -878,7 +878,7 @@ EXPORT_SYMBOL(mem_cgroup_from_task);
 
 static __always_inline struct mem_cgroup *active_memcg(void)
 {
-       if (in_interrupt())
+       if (!in_task())
                return this_cpu_read(int_active_memcg);
        else
                return current->active_memcg;