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    Subject[PATCH] memcg: replace in_interrupt() by !in_task() in active_memcg()
    Date
    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
    Fixes: 37d5985c003d ("mm: kmem: prepare remote memcg charging infra for interrupt contexts")
    Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
    ---
    include/linux/sched/mm.h | 2 +-
    mm/memcontrol.c | 2 +-
    2 files changed, 2 insertions(+), 2 deletions(-)

    diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
    index e24b1fe348e3..9dd071f78dba 100644
    --- 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 ae1f5d0cb581..3ebf792ef2c0 100644
    --- a/mm/memcontrol.c
    +++ b/mm/memcontrol.c
    @@ -905,7 +905,7 @@ 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;
    --
    2.25.1
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