On Tue, 13 May 2014 17:29:16 +0200 Michal Hocko <mho...@suse.cz> wrote:
> force_empty has been introduced primarily to drop memory before it gets
> reparented on the group removal. This alone doesn't sound fully
> justified because reparented pages which are not in use can be reclaimed
> also later when there is a memory pressure on the parent level.
>
> Mark the knob CFTYPE_INSANE which tells the cgroup core that it
> shouldn't create the knob with the experimental sane_behavior. Other
> users will get informed about the deprecation and asked to tell us more
> because I do not expect most users will use sane_behavior cgroups mode
> very soon.
> Anyway I expect that most users will be simply cgroup remove handlers
> which do that since ever without having any good reason for it.
>
> If somebody really cares because reparented pages, which would be
> dropped otherwise, push out more important ones then we should fix the
> reparenting code and put pages to the tail.
>
> ...
>
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4793,6 +4793,10 @@ static int mem_cgroup_force_empty_write(struct
> cgroup_subsys_state *css,
>
> if (mem_cgroup_is_root(memcg))
> return -EINVAL;
> + pr_info("%s (%d): memory.force_empty is deprecated and will be
> removed.",
> + current->comm, task_pid_nr(current));
> + pr_cont(" Let us know if you know if it needed in your usecase at");
> + pr_cont(" linux...@kvack.org\n");
> return mem_cgroup_force_empty(memcg);
> }
>
Do we really want to spam the poor user each and every time they use
this? Using pr_info_once() is kinder and gentler?
From: Andrew Morton <a...@linux-foundation.org>
Subject: memcg-deprecate-memoryforce_empty-knob-fix
- s/pr_info/pr_info_once/
- fix garbled printk text
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: Michal Hocko <mho...@suse.cz>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
---
Documentation/cgroups/memory.txt | 2 +-
mm/memcontrol.c | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)
diff -puN
Documentation/cgroups/memory.txt~memcg-deprecate-memoryforce_empty-knob-fix
Documentation/cgroups/memory.txt
---
a/Documentation/cgroups/memory.txt~memcg-deprecate-memoryforce_empty-knob-fix
+++ a/Documentation/cgroups/memory.txt
@@ -482,7 +482,7 @@ About use_hierarchy, see Section 6.
memory.kmem.usage_in_bytes == memory.usage_in_bytes.
Please note that this knob is considered deprecated and will be removed
- in future.
+ in the future.
About use_hierarchy, see Section 6.
diff -puN mm/memcontrol.c~memcg-deprecate-memoryforce_empty-knob-fix
mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-deprecate-memoryforce_empty-knob-fix
+++ a/mm/memcontrol.c
@@ -4799,10 +4799,10 @@ static int mem_cgroup_force_empty_write(
if (mem_cgroup_is_root(memcg))
return -EINVAL;
- pr_info("%s (%d): memory.force_empty is deprecated and will be
removed.",
- current->comm, task_pid_nr(current));
- pr_cont(" Let us know if you know if it needed in your usecase at");
- pr_cont(" linux...@kvack.org\n");
+ pr_info_once("%s (%d): memory.force_empty is deprecated and will be "
+ "removed. Let us know if it is needed in your usecase at "
+ "linux...@kvack.org\n",
+ current->comm, task_pid_nr(current));
return mem_cgroup_force_empty(memcg);
}
_
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