2022-01-28 09:36:36

by Shakeel Butt

Subject: [PATCH] memcg: replace in_interrupt() with !in_task()

Replace the deprecated in_interrupt() with !in_task() because
in_interrupt() returns true for BH disabled even if the call happens in
the task context. in_task() is the right interface to differentiate
task context from NMI, hard IRQ and softirq contexts.

Signed-off-by: Shakeel Butt <[email protected]>
---
mm/memcontrol.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d067366002e6..215dfe325e9d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2688,7 +2688,7 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
READ_ONCE(memcg->swap.high);

/* Don't bother a random interrupted task */
- if (in_interrupt()) {
+ if (!in_task()) {
if (mem_high) {
schedule_work(&memcg->high_work);
break;
@@ -6968,7 +6968,7 @@ void mem_cgroup_sk_alloc(struct sock *sk)
return;

/* Do not associate the sock with unrelated interrupted task's memcg. */
- if (in_interrupt())
+ if (!in_task())
return;

rcu_read_lock();
--
2.35.0.rc0.227.g00780c9af4-goog

2022-01-31 10:10:42

by Michal Hocko

Subject: Re: [PATCH] memcg: replace in_interrupt() with !in_task()

On Thu 27-01-22 08:26:36, Shakeel Butt wrote:
> Replace the deprecated in_interrupt() with !in_task() because
> in_interrupt() returns true for BH disabled even if the call happens in
> the task context. in_task() is the right interface to differentiate
> task context from NMI, hard IRQ and softirq contexts.

Makes sense. I do not think this will have any visible effect. Except
for removing a deprecated call, right?

> Signed-off-by: Shakeel Butt <[email protected]>

Acked-by: Michal Hocko <[email protected]>

Thanks!

> ---
> mm/memcontrol.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index d067366002e6..215dfe325e9d 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2688,7 +2688,7 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
> READ_ONCE(memcg->swap.high);
>
> /* Don't bother a random interrupted task */
> - if (in_interrupt()) {
> + if (!in_task()) {
> if (mem_high) {
> schedule_work(&memcg->high_work);
> break;
> @@ -6968,7 +6968,7 @@ void mem_cgroup_sk_alloc(struct sock *sk)
> return;
>
> /* Do not associate the sock with unrelated interrupted task's memcg. */
> - if (in_interrupt())
> + if (!in_task())
> return;
>
> rcu_read_lock();
> --
> 2.35.0.rc0.227.g00780c9af4-goog

--
Michal Hocko
SUSE Labs

2022-01-31 11:16:59

by Shakeel Butt

Subject: Re: [PATCH] memcg: replace in_interrupt() with !in_task()

On Fri, Jan 28, 2022 at 4:23 AM Michal Hocko <[email protected]> wrote:
>
> On Thu 27-01-22 08:26:36, Shakeel Butt wrote:
> > Replace the deprecated in_interrupt() with !in_task() because
> > in_interrupt() returns true for BH disabled even if the call happens in
> > the task context. in_task() is the right interface to differentiate
> > task context from NMI, hard IRQ and softirq contexts.
>
> Makes sense. I do not think this will have any visible effect. Except
> for removing a deprecated call, right?

Correct, that is my understanding as well.