include/linux/memcontrol.h | 32 ++------------------------------ mm/memcontrol.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 30 deletions(-)
The function __memcg_memory_event has been unnecessarily marked inline
even when it is not really performance critical. It is usually called
to track extreme conditions. Over the time, it has evolved to include
more functionality and inlining it is causing more harm.
Before the patch:
$ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o
text data bss dec hex filename
35645 10574 4192 50411 c4eb mm/memcontrol.o
54738 1658 0 56396 dc4c net/ipv4/tcp_input.o
34644 1065 0 35709 8b7d net/ipv4/tcp_output.o
After the patch:
$ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o
text data bss dec hex filename
35137 10446 4192 49775 c26f mm/memcontrol.o
54322 1562 0 55884 da4c net/ipv4/tcp_input.o
34492 1017 0 35509 8ab5 net/ipv4/tcp_output.o
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
---
include/linux/memcontrol.h | 32 ++------------------------------
mm/memcontrol.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+), 30 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d37e7c93bb8c..8d2e250535a8 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1002,36 +1002,8 @@ static inline void count_memcg_event_mm(struct mm_struct *mm,
count_memcg_events_mm(mm, idx, 1);
}
-static inline void __memcg_memory_event(struct mem_cgroup *memcg,
- enum memcg_memory_event event,
- bool allow_spinning)
-{
- bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
- event == MEMCG_SWAP_FAIL;
-
- /* For now only MEMCG_MAX can happen with !allow_spinning context. */
- VM_WARN_ON_ONCE(!allow_spinning && event != MEMCG_MAX);
-
- atomic_long_inc(&memcg->memory_events_local[event]);
- if (!swap_event && allow_spinning)
- cgroup_file_notify(&memcg->events_local_file);
-
- do {
- atomic_long_inc(&memcg->memory_events[event]);
- if (allow_spinning) {
- if (swap_event)
- cgroup_file_notify(&memcg->swap_events_file);
- else
- cgroup_file_notify(&memcg->events_file);
- }
-
- if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
- break;
- if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
- break;
- } while ((memcg = parent_mem_cgroup(memcg)) &&
- !mem_cgroup_is_root(memcg));
-}
+void __memcg_memory_event(struct mem_cgroup *memcg,
+ enum memcg_memory_event event, bool allow_spinning);
static inline void memcg_memory_event(struct mem_cgroup *memcg,
enum memcg_memory_event event)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1a95049d8b88..93f7c76f0ce9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1626,6 +1626,37 @@ unsigned long mem_cgroup_size(struct mem_cgroup *memcg)
return page_counter_read(&memcg->memory);
}
+void __memcg_memory_event(struct mem_cgroup *memcg,
+ enum memcg_memory_event event, bool allow_spinning)
+{
+ bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
+ event == MEMCG_SWAP_FAIL;
+
+ /* For now only MEMCG_MAX can happen with !allow_spinning context. */
+ VM_WARN_ON_ONCE(!allow_spinning && event != MEMCG_MAX);
+
+ atomic_long_inc(&memcg->memory_events_local[event]);
+ if (!swap_event && allow_spinning)
+ cgroup_file_notify(&memcg->events_local_file);
+
+ do {
+ atomic_long_inc(&memcg->memory_events[event]);
+ if (allow_spinning) {
+ if (swap_event)
+ cgroup_file_notify(&memcg->swap_events_file);
+ else
+ cgroup_file_notify(&memcg->events_file);
+ }
+
+ if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
+ break;
+ if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
+ break;
+ } while ((memcg = parent_mem_cgroup(memcg)) &&
+ !mem_cgroup_is_root(memcg));
+}
+EXPORT_SYMBOL(__memcg_memory_event);
+
static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
int order)
{
--
2.47.3On Tue 21-10-25 16:44:25, Shakeel Butt wrote: > The function __memcg_memory_event has been unnecessarily marked inline > even when it is not really performance critical. It is usually called > to track extreme conditions. Over the time, it has evolved to include > more functionality and inlining it is causing more harm. > > Before the patch: > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o > text data bss dec hex filename > 35645 10574 4192 50411 c4eb mm/memcontrol.o > 54738 1658 0 56396 dc4c net/ipv4/tcp_input.o > 34644 1065 0 35709 8b7d net/ipv4/tcp_output.o > > After the patch: > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o > text data bss dec hex filename > 35137 10446 4192 49775 c26f mm/memcontrol.o > 54322 1562 0 55884 da4c net/ipv4/tcp_input.o > 34492 1017 0 35509 8ab5 net/ipv4/tcp_output.o > > Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> As the only user is in tree should we make that EXPORT_SYMBOL_GPL instead? -- Michal Hocko SUSE Labs
On Thu, Oct 23, 2025 at 03:18:14PM +0200, Michal Hocko wrote: > As the only user is in tree should we make that EXPORT_SYMBOL_GPL > instead? Yes.
On Thu, Oct 23, 2025 at 03:18:14PM +0200, Michal Hocko wrote: > On Tue 21-10-25 16:44:25, Shakeel Butt wrote: > > The function __memcg_memory_event has been unnecessarily marked inline > > even when it is not really performance critical. It is usually called > > to track extreme conditions. Over the time, it has evolved to include > > more functionality and inlining it is causing more harm. > > > > Before the patch: > > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o > > text data bss dec hex filename > > 35645 10574 4192 50411 c4eb mm/memcontrol.o > > 54738 1658 0 56396 dc4c net/ipv4/tcp_input.o > > 34644 1065 0 35709 8b7d net/ipv4/tcp_output.o > > > > After the patch: > > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o > > text data bss dec hex filename > > 35137 10446 4192 49775 c26f mm/memcontrol.o > > 54322 1562 0 55884 da4c net/ipv4/tcp_input.o > > 34492 1017 0 35509 8ab5 net/ipv4/tcp_output.o > > > > Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> > > Acked-by: Michal Hocko <mhocko@suse.com> Thanks. > > As the only user is in tree should we make that EXPORT_SYMBOL_GPL > instead? I just followed the file convention i.e. all other exports in memcontrol.c are like that. I would keep this as is unless you have strong opinion otherwise.
On Tue, 21 Oct 2025 16:44:25 -0700 Shakeel Butt <shakeel.butt@linux.dev> wrote:
> The function __memcg_memory_event has been unnecessarily marked inline
> even when it is not really performance critical. It is usually called
> to track extreme conditions. Over the time, it has evolved to include
> more functionality and inlining it is causing more harm.
>
> Before the patch:
> $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o
> text data bss dec hex filename
> 35645 10574 4192 50411 c4eb mm/memcontrol.o
> 54738 1658 0 56396 dc4c net/ipv4/tcp_input.o
> 34644 1065 0 35709 8b7d net/ipv4/tcp_output.o
>
> After the patch:
> $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o
> text data bss dec hex filename
> 35137 10446 4192 49775 c26f mm/memcontrol.o
> 54322 1562 0 55884 da4c net/ipv4/tcp_input.o
> 34492 1017 0 35509 8ab5 net/ipv4/tcp_output.o
>
> Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
> ---
> include/linux/memcontrol.h | 32 ++------------------------------
> mm/memcontrol.c | 31 +++++++++++++++++++++++++++++++
> 2 files changed, 33 insertions(+), 30 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index d37e7c93bb8c..8d2e250535a8 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1002,36 +1002,8 @@ static inline void count_memcg_event_mm(struct mm_struct *mm,
> count_memcg_events_mm(mm, idx, 1);
> }
>
> -static inline void __memcg_memory_event(struct mem_cgroup *memcg,
> - enum memcg_memory_event event,
> - bool allow_spinning)
> -{
> - bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
> - event == MEMCG_SWAP_FAIL;
> -
> - /* For now only MEMCG_MAX can happen with !allow_spinning context. */
> - VM_WARN_ON_ONCE(!allow_spinning && event != MEMCG_MAX);
> -
> - atomic_long_inc(&memcg->memory_events_local[event]);
> - if (!swap_event && allow_spinning)
> - cgroup_file_notify(&memcg->events_local_file);
> -
> - do {
> - atomic_long_inc(&memcg->memory_events[event]);
> - if (allow_spinning) {
> - if (swap_event)
> - cgroup_file_notify(&memcg->swap_events_file);
> - else
> - cgroup_file_notify(&memcg->events_file);
> - }
> -
> - if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> - break;
> - if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
> - break;
> - } while ((memcg = parent_mem_cgroup(memcg)) &&
> - !mem_cgroup_is_root(memcg));
> -}
> +void __memcg_memory_event(struct mem_cgroup *memcg,
> + enum memcg_memory_event event, bool allow_spinning);
>
> static inline void memcg_memory_event(struct mem_cgroup *memcg,
> enum memcg_memory_event event)
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 1a95049d8b88..93f7c76f0ce9 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1626,6 +1626,37 @@ unsigned long mem_cgroup_size(struct mem_cgroup *memcg)
> return page_counter_read(&memcg->memory);
> }
>
> +void __memcg_memory_event(struct mem_cgroup *memcg,
> + enum memcg_memory_event event, bool allow_spinning)
Seems this function is called only from memcontrol.c. Why not making it a
static function?
> +{
> + bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
> + event == MEMCG_SWAP_FAIL;
> +
> + /* For now only MEMCG_MAX can happen with !allow_spinning context. */
> + VM_WARN_ON_ONCE(!allow_spinning && event != MEMCG_MAX);
> +
> + atomic_long_inc(&memcg->memory_events_local[event]);
> + if (!swap_event && allow_spinning)
> + cgroup_file_notify(&memcg->events_local_file);
> +
> + do {
> + atomic_long_inc(&memcg->memory_events[event]);
> + if (allow_spinning) {
> + if (swap_event)
> + cgroup_file_notify(&memcg->swap_events_file);
> + else
> + cgroup_file_notify(&memcg->events_file);
> + }
> +
> + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> + break;
> + if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
> + break;
> + } while ((memcg = parent_mem_cgroup(memcg)) &&
> + !mem_cgroup_is_root(memcg));
> +}
> +EXPORT_SYMBOL(__memcg_memory_event);
Also, seems there is no reason to export this symbol?
Thanks,
SJ
[...]
On Tue, Oct 21, 2025 at 05:58:00PM -0700, SeongJae Park wrote:
> On Tue, 21 Oct 2025 16:44:25 -0700 Shakeel Butt <shakeel.butt@linux.dev> wrote:
>
> > The function __memcg_memory_event has been unnecessarily marked inline
> > even when it is not really performance critical. It is usually called
> > to track extreme conditions. Over the time, it has evolved to include
> > more functionality and inlining it is causing more harm.
> >
> > Before the patch:
> > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o
> > text data bss dec hex filename
> > 35645 10574 4192 50411 c4eb mm/memcontrol.o
> > 54738 1658 0 56396 dc4c net/ipv4/tcp_input.o
> > 34644 1065 0 35709 8b7d net/ipv4/tcp_output.o
> >
> > After the patch:
> > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o
> > text data bss dec hex filename
> > 35137 10446 4192 49775 c26f mm/memcontrol.o
> > 54322 1562 0 55884 da4c net/ipv4/tcp_input.o
> > 34492 1017 0 35509 8ab5 net/ipv4/tcp_output.o
> >
> > Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
> > ---
> > include/linux/memcontrol.h | 32 ++------------------------------
> > mm/memcontrol.c | 31 +++++++++++++++++++++++++++++++
> > 2 files changed, 33 insertions(+), 30 deletions(-)
> >
> > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > index d37e7c93bb8c..8d2e250535a8 100644
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -1002,36 +1002,8 @@ static inline void count_memcg_event_mm(struct mm_struct *mm,
> > count_memcg_events_mm(mm, idx, 1);
> > }
> >
> > -static inline void __memcg_memory_event(struct mem_cgroup *memcg,
> > - enum memcg_memory_event event,
> > - bool allow_spinning)
> > -{
> > - bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
> > - event == MEMCG_SWAP_FAIL;
> > -
> > - /* For now only MEMCG_MAX can happen with !allow_spinning context. */
> > - VM_WARN_ON_ONCE(!allow_spinning && event != MEMCG_MAX);
> > -
> > - atomic_long_inc(&memcg->memory_events_local[event]);
> > - if (!swap_event && allow_spinning)
> > - cgroup_file_notify(&memcg->events_local_file);
> > -
> > - do {
> > - atomic_long_inc(&memcg->memory_events[event]);
> > - if (allow_spinning) {
> > - if (swap_event)
> > - cgroup_file_notify(&memcg->swap_events_file);
> > - else
> > - cgroup_file_notify(&memcg->events_file);
> > - }
> > -
> > - if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> > - break;
> > - if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
> > - break;
> > - } while ((memcg = parent_mem_cgroup(memcg)) &&
> > - !mem_cgroup_is_root(memcg));
> > -}
> > +void __memcg_memory_event(struct mem_cgroup *memcg,
> > + enum memcg_memory_event event, bool allow_spinning);
> >
> > static inline void memcg_memory_event(struct mem_cgroup *memcg,
> > enum memcg_memory_event event)
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 1a95049d8b88..93f7c76f0ce9 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -1626,6 +1626,37 @@ unsigned long mem_cgroup_size(struct mem_cgroup *memcg)
> > return page_counter_read(&memcg->memory);
> > }
> >
> > +void __memcg_memory_event(struct mem_cgroup *memcg,
> > + enum memcg_memory_event event, bool allow_spinning)
>
> Seems this function is called only from memcontrol.c. Why not making it a
> static function?
There is a recent code where this is called (indirectly) from networking
stack for MEMCG_SOCK_THROTTLED.
>
> > +{
> > + bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
> > + event == MEMCG_SWAP_FAIL;
> > +
> > + /* For now only MEMCG_MAX can happen with !allow_spinning context. */
> > + VM_WARN_ON_ONCE(!allow_spinning && event != MEMCG_MAX);
> > +
> > + atomic_long_inc(&memcg->memory_events_local[event]);
> > + if (!swap_event && allow_spinning)
> > + cgroup_file_notify(&memcg->events_local_file);
> > +
> > + do {
> > + atomic_long_inc(&memcg->memory_events[event]);
> > + if (allow_spinning) {
> > + if (swap_event)
> > + cgroup_file_notify(&memcg->swap_events_file);
> > + else
> > + cgroup_file_notify(&memcg->events_file);
> > + }
> > +
> > + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> > + break;
> > + if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
> > + break;
> > + } while ((memcg = parent_mem_cgroup(memcg)) &&
> > + !mem_cgroup_is_root(memcg));
> > +}
> > +EXPORT_SYMBOL(__memcg_memory_event);
>
> Also, seems there is no reason to export this symbol?
The networking code needs this export.
Thanks for taking a look.
Shakeel Butt <shakeel.butt@linux.dev> writes: > On Tue, Oct 21, 2025 at 05:58:00PM -0700, SeongJae Park wrote: >> On Tue, 21 Oct 2025 16:44:25 -0700 Shakeel Butt <shakeel.butt@linux.dev> wrote: >> >> > The function __memcg_memory_event has been unnecessarily marked inline >> > even when it is not really performance critical. It is usually called >> > to track extreme conditions. Over the time, it has evolved to include >> > more functionality and inlining it is causing more harm. >> > >> > Before the patch: >> > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o >> > text data bss dec hex filename >> > 35645 10574 4192 50411 c4eb mm/memcontrol.o >> > 54738 1658 0 56396 dc4c net/ipv4/tcp_input.o >> > 34644 1065 0 35709 8b7d net/ipv4/tcp_output.o >> > >> > After the patch: >> > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o >> > text data bss dec hex filename >> > 35137 10446 4192 49775 c26f mm/memcontrol.o >> > 54322 1562 0 55884 da4c net/ipv4/tcp_input.o >> > 34492 1017 0 35509 8ab5 net/ipv4/tcp_output.o >> > >> > Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Thanks!
On Tue, 21 Oct 2025 18:28:02 -0700 Shakeel Butt <shakeel.butt@linux.dev> wrote:
> On Tue, Oct 21, 2025 at 05:58:00PM -0700, SeongJae Park wrote:
> > On Tue, 21 Oct 2025 16:44:25 -0700 Shakeel Butt <shakeel.butt@linux.dev> wrote:
> >
> > > The function __memcg_memory_event has been unnecessarily marked inline
> > > even when it is not really performance critical. It is usually called
> > > to track extreme conditions. Over the time, it has evolved to include
> > > more functionality and inlining it is causing more harm.
> > >
> > > Before the patch:
> > > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o
> > > text data bss dec hex filename
> > > 35645 10574 4192 50411 c4eb mm/memcontrol.o
> > > 54738 1658 0 56396 dc4c net/ipv4/tcp_input.o
> > > 34644 1065 0 35709 8b7d net/ipv4/tcp_output.o
> > >
> > > After the patch:
> > > $ size mm/memcontrol.o net/ipv4/tcp_input.o net/ipv4/tcp_output.o
> > > text data bss dec hex filename
> > > 35137 10446 4192 49775 c26f mm/memcontrol.o
> > > 54322 1562 0 55884 da4c net/ipv4/tcp_input.o
> > > 34492 1017 0 35509 8ab5 net/ipv4/tcp_output.o
> > >
> > > Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
> > > ---
> > > include/linux/memcontrol.h | 32 ++------------------------------
> > > mm/memcontrol.c | 31 +++++++++++++++++++++++++++++++
> > > 2 files changed, 33 insertions(+), 30 deletions(-)
> > >
> > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > > index d37e7c93bb8c..8d2e250535a8 100644
> > > --- a/include/linux/memcontrol.h
> > > +++ b/include/linux/memcontrol.h
> > > @@ -1002,36 +1002,8 @@ static inline void count_memcg_event_mm(struct mm_struct *mm,
> > > count_memcg_events_mm(mm, idx, 1);
> > > }
> > >
> > > -static inline void __memcg_memory_event(struct mem_cgroup *memcg,
> > > - enum memcg_memory_event event,
> > > - bool allow_spinning)
> > > -{
> > > - bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
> > > - event == MEMCG_SWAP_FAIL;
> > > -
> > > - /* For now only MEMCG_MAX can happen with !allow_spinning context. */
> > > - VM_WARN_ON_ONCE(!allow_spinning && event != MEMCG_MAX);
> > > -
> > > - atomic_long_inc(&memcg->memory_events_local[event]);
> > > - if (!swap_event && allow_spinning)
> > > - cgroup_file_notify(&memcg->events_local_file);
> > > -
> > > - do {
> > > - atomic_long_inc(&memcg->memory_events[event]);
> > > - if (allow_spinning) {
> > > - if (swap_event)
> > > - cgroup_file_notify(&memcg->swap_events_file);
> > > - else
> > > - cgroup_file_notify(&memcg->events_file);
> > > - }
> > > -
> > > - if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> > > - break;
> > > - if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
> > > - break;
> > > - } while ((memcg = parent_mem_cgroup(memcg)) &&
> > > - !mem_cgroup_is_root(memcg));
> > > -}
> > > +void __memcg_memory_event(struct mem_cgroup *memcg,
> > > + enum memcg_memory_event event, bool allow_spinning);
> > >
> > > static inline void memcg_memory_event(struct mem_cgroup *memcg,
> > > enum memcg_memory_event event)
> > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > > index 1a95049d8b88..93f7c76f0ce9 100644
> > > --- a/mm/memcontrol.c
> > > +++ b/mm/memcontrol.c
> > > @@ -1626,6 +1626,37 @@ unsigned long mem_cgroup_size(struct mem_cgroup *memcg)
> > > return page_counter_read(&memcg->memory);
> > > }
> > >
> > > +void __memcg_memory_event(struct mem_cgroup *memcg,
> > > + enum memcg_memory_event event, bool allow_spinning)
> >
> > Seems this function is called only from memcontrol.c. Why not making it a
> > static function?
>
> There is a recent code where this is called (indirectly) from networking
> stack for MEMCG_SOCK_THROTTLED.
Thank you for enlightening me. Apparently the code is from
https://lore.kernel.org/20251016161035.86161-1-shakeel.butt@linux.dev.
>
> >
> > > +{
> > > + bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
> > > + event == MEMCG_SWAP_FAIL;
> > > +
> > > + /* For now only MEMCG_MAX can happen with !allow_spinning context. */
> > > + VM_WARN_ON_ONCE(!allow_spinning && event != MEMCG_MAX);
> > > +
> > > + atomic_long_inc(&memcg->memory_events_local[event]);
> > > + if (!swap_event && allow_spinning)
> > > + cgroup_file_notify(&memcg->events_local_file);
> > > +
> > > + do {
> > > + atomic_long_inc(&memcg->memory_events[event]);
> > > + if (allow_spinning) {
> > > + if (swap_event)
> > > + cgroup_file_notify(&memcg->swap_events_file);
> > > + else
> > > + cgroup_file_notify(&memcg->events_file);
> > > + }
> > > +
> > > + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> > > + break;
> > > + if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
> > > + break;
> > > + } while ((memcg = parent_mem_cgroup(memcg)) &&
> > > + !mem_cgroup_is_root(memcg));
> > > +}
> > > +EXPORT_SYMBOL(__memcg_memory_event);
> >
> > Also, seems there is no reason to export this symbol?
>
> The networking code needs this export.
>
> Thanks for taking a look.
Again, thank you for clarifying.
Acked-by: SeongJae Park <sj@kernel.org>
Thanks,
SJ
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