diff mbox series

[v2,1/2] mm/memcg: rename mem_cgroup_split_huge_fixup to split_page_memcg

Message ID 20210304074053.65527-2-zhouguanghui1@huawei.com (mailing list archive)
State New
Headers show
Series set memcg when split page | expand

Commit Message

Zhou Guanghui March 4, 2021, 7:40 a.m. UTC
Rename mem_cgroup_split_huge_fixup to split_page_memcg and explicitly
pass in page number argument.

In this way, the interface name is more common and can be used by
potential users. In addition, the complete info(memcg and flag) of
the memcg needs to be set to the tail pages.

Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>
---
 include/linux/memcontrol.h |  6 ++----
 mm/huge_memory.c           |  2 +-
 mm/memcontrol.c            | 15 ++++++---------
 3 files changed, 9 insertions(+), 14 deletions(-)

Comments

Johannes Weiner March 4, 2021, 3:50 p.m. UTC | #1
On Thu, Mar 04, 2021 at 07:40:52AM +0000, Zhou Guanghui wrote:
> Rename mem_cgroup_split_huge_fixup to split_page_memcg and explicitly
> pass in page number argument.
> 
> In this way, the interface name is more common and can be used by
> potential users. In addition, the complete info(memcg and flag) of
> the memcg needs to be set to the tail pages.
> 
> Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Zi Yan March 4, 2021, 4:20 p.m. UTC | #2
On 4 Mar 2021, at 2:40, Zhou Guanghui wrote:

> Rename mem_cgroup_split_huge_fixup to split_page_memcg and explicitly
> pass in page number argument.
>
> In this way, the interface name is more common and can be used by
> potential users. In addition, the complete info(memcg and flag) of
> the memcg needs to be set to the tail pages.
>
> Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>
> ---
>  include/linux/memcontrol.h |  6 ++----
>  mm/huge_memory.c           |  2 +-
>  mm/memcontrol.c            | 15 ++++++---------
>  3 files changed, 9 insertions(+), 14 deletions(-)
>
LGTM. Thanks.

Reviewed-by: Zi Yan <ziy@nvidia.com>

—
Best Regards,
Yan Zi
Shakeel Butt March 4, 2021, 6:54 p.m. UTC | #3
On Wed, Mar 3, 2021 at 11:55 PM Zhou Guanghui <zhouguanghui1@huawei.com> wrote:
>
> Rename mem_cgroup_split_huge_fixup to split_page_memcg and explicitly
> pass in page number argument.
>
> In this way, the interface name is more common and can be used by
> potential users. In addition, the complete info(memcg and flag) of
> the memcg needs to be set to the tail pages.
>
> Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>

Reviewed-by: Shakeel Butt <shakeelb@google.com>
Balbir Singh March 8, 2021, 10:37 p.m. UTC | #4
On 4/3/21 6:40 pm, Zhou Guanghui wrote:
> Rename mem_cgroup_split_huge_fixup to split_page_memcg and explicitly
> pass in page number argument.
> 
> In this way, the interface name is more common and can be used by
> potential users. In addition, the complete info(memcg and flag) of
> the memcg needs to be set to the tail pages.
> 
> Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>
> ---
>  include/linux/memcontrol.h |  6 ++----
>  mm/huge_memory.c           |  2 +-
>  mm/memcontrol.c            | 15 ++++++---------
>  3 files changed, 9 insertions(+), 14 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index e6dc793d587d..0c04d39a7967 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1061,9 +1061,7 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm,
>  	rcu_read_unlock();
>  }
>  
> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -void mem_cgroup_split_huge_fixup(struct page *head);
> -#endif
> +void split_page_memcg(struct page *head, unsigned int nr);
>  
>  #else /* CONFIG_MEMCG */
>  
> @@ -1400,7 +1398,7 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
>  	return 0;
>  }
>  
> -static inline void mem_cgroup_split_huge_fixup(struct page *head)
> +static inline void split_page_memcg(struct page *head, unsigned int nr)
>  {
>  }
>  
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 395c75111d33..e7f29308ebc8 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2471,7 +2471,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
>  	int i;
>  
>  	/* complete memcg works before add pages to LRU */
> -	mem_cgroup_split_huge_fixup(head);
> +	split_page_memcg(head, nr);
>  
>  	if (PageAnon(head) && PageSwapCache(head)) {
>  		swp_entry_t entry = { .val = page_private(head) };
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 845eec01ef9d..e064ac0d850a 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3287,24 +3287,21 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
>  
>  #endif /* CONFIG_MEMCG_KMEM */
>  
> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  /*
> - * Because page_memcg(head) is not set on compound tails, set it now.
> + * Because page_memcg(head) is not set on tails, set it now.
>   */
> -void mem_cgroup_split_huge_fixup(struct page *head)
> +void split_page_memcg(struct page *head, unsigned int nr)
>  {

Do we need input validation on nr? Can nr be aribtrary or can we enforce

VM_BUG_ON(!is_power_of_2(nr));


Balbir Singh
Michal Hocko March 9, 2021, 8:28 a.m. UTC | #5
On Tue 09-03-21 09:37:29, Balbir Singh wrote:
> On 4/3/21 6:40 pm, Zhou Guanghui wrote:
[...]
> > -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> >  /*
> > - * Because page_memcg(head) is not set on compound tails, set it now.
> > + * Because page_memcg(head) is not set on tails, set it now.
> >   */
> > -void mem_cgroup_split_huge_fixup(struct page *head)
> > +void split_page_memcg(struct page *head, unsigned int nr)
> >  {
> 
> Do we need input validation on nr? Can nr be aribtrary or can we enforce
> 
> VM_BUG_ON(!is_power_of_2(nr));

In practice this will be power of 2 but why should we bother to sanitze
that?
Balbir Singh March 10, 2021, 9:44 p.m. UTC | #6
On 9/3/21 7:28 pm, Michal Hocko wrote:
> On Tue 09-03-21 09:37:29, Balbir Singh wrote:
>> On 4/3/21 6:40 pm, Zhou Guanghui wrote:
> [...]
>>> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>>  /*
>>> - * Because page_memcg(head) is not set on compound tails, set it now.
>>> + * Because page_memcg(head) is not set on tails, set it now.
>>>   */
>>> -void mem_cgroup_split_huge_fixup(struct page *head)
>>> +void split_page_memcg(struct page *head, unsigned int nr)
>>>  {
>>
>> Do we need input validation on nr? Can nr be aribtrary or can we enforce
>>
>> VM_BUG_ON(!is_power_of_2(nr));
> 
> In practice this will be power of 2 but why should we bother to sanitze
> that? 
> 

Just when DEBUG_VM is enabled to ensure the contract is valid, given that
nr is now variable, we could end up with subtle bugs unless we can audit
all callers. Even the power of 2 check does not catch the fact that nr
is indeed what we expect, but it still checks a large range of invalid
inputs.

Balbir Singh.
Hugh Dickins March 10, 2021, 10 p.m. UTC | #7
On Thu, 11 Mar 2021, Singh, Balbir wrote:
> On 9/3/21 7:28 pm, Michal Hocko wrote:
> > On Tue 09-03-21 09:37:29, Balbir Singh wrote:
> >> On 4/3/21 6:40 pm, Zhou Guanghui wrote:
> > [...]
> >>> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> >>>  /*
> >>> - * Because page_memcg(head) is not set on compound tails, set it now.
> >>> + * Because page_memcg(head) is not set on tails, set it now.
> >>>   */
> >>> -void mem_cgroup_split_huge_fixup(struct page *head)
> >>> +void split_page_memcg(struct page *head, unsigned int nr)
> >>>  {
> >>
> >> Do we need input validation on nr? Can nr be aribtrary or can we enforce
> >>
> >> VM_BUG_ON(!is_power_of_2(nr));
> > 
> > In practice this will be power of 2 but why should we bother to sanitze
> > that? 
> > 
> 
> Just when DEBUG_VM is enabled to ensure the contract is valid, given that
> nr is now variable, we could end up with subtle bugs unless we can audit
> all callers. Even the power of 2 check does not catch the fact that nr
> is indeed what we expect, but it still checks a large range of invalid
> inputs.

I think you imagine this is something it's not.

"all callers" are __split_huge_page() and split_page() (maybe Matthew
will have a third caller, maybe not).  It is not something drivers will
be calling directly themselves, and it won't ever get EXPORTed to them.

Hugh
Balbir Singh March 10, 2021, 11:50 p.m. UTC | #8
On 11/3/21 9:00 am, Hugh Dickins wrote:
> On Thu, 11 Mar 2021, Singh, Balbir wrote:
>> On 9/3/21 7:28 pm, Michal Hocko wrote:
>>> On Tue 09-03-21 09:37:29, Balbir Singh wrote:
>>>> On 4/3/21 6:40 pm, Zhou Guanghui wrote:
>>> [...]
>>>>> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>>>>  /*
>>>>> - * Because page_memcg(head) is not set on compound tails, set it now.
>>>>> + * Because page_memcg(head) is not set on tails, set it now.
>>>>>   */
>>>>> -void mem_cgroup_split_huge_fixup(struct page *head)
>>>>> +void split_page_memcg(struct page *head, unsigned int nr)
>>>>>  {
>>>>
>>>> Do we need input validation on nr? Can nr be aribtrary or can we enforce
>>>>
>>>> VM_BUG_ON(!is_power_of_2(nr));
>>>
>>> In practice this will be power of 2 but why should we bother to sanitze
>>> that? 
>>>
>>
>> Just when DEBUG_VM is enabled to ensure the contract is valid, given that
>> nr is now variable, we could end up with subtle bugs unless we can audit
>> all callers. Even the power of 2 check does not catch the fact that nr
>> is indeed what we expect, but it still checks a large range of invalid
>> inputs.
> 
> I think you imagine this is something it's not.
> 
> "all callers" are __split_huge_page() and split_page() (maybe Matthew
> will have a third caller, maybe not).  It is not something drivers will
> be calling directly themselves, and it won't ever get EXPORTed to them.
> 

Don't feel strongly about it if that is the case.

Thanks,
Balbir Singh
diff mbox series

Patch

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e6dc793d587d..0c04d39a7967 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1061,9 +1061,7 @@  static inline void memcg_memory_event_mm(struct mm_struct *mm,
 	rcu_read_unlock();
 }
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-void mem_cgroup_split_huge_fixup(struct page *head);
-#endif
+void split_page_memcg(struct page *head, unsigned int nr);
 
 #else /* CONFIG_MEMCG */
 
@@ -1400,7 +1398,7 @@  unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 	return 0;
 }
 
-static inline void mem_cgroup_split_huge_fixup(struct page *head)
+static inline void split_page_memcg(struct page *head, unsigned int nr)
 {
 }
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 395c75111d33..e7f29308ebc8 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2471,7 +2471,7 @@  static void __split_huge_page(struct page *page, struct list_head *list,
 	int i;
 
 	/* complete memcg works before add pages to LRU */
-	mem_cgroup_split_huge_fixup(head);
+	split_page_memcg(head, nr);
 
 	if (PageAnon(head) && PageSwapCache(head)) {
 		swp_entry_t entry = { .val = page_private(head) };
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 845eec01ef9d..e064ac0d850a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3287,24 +3287,21 @@  void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
 
 #endif /* CONFIG_MEMCG_KMEM */
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 /*
- * Because page_memcg(head) is not set on compound tails, set it now.
+ * Because page_memcg(head) is not set on tails, set it now.
  */
-void mem_cgroup_split_huge_fixup(struct page *head)
+void split_page_memcg(struct page *head, unsigned int nr)
 {
 	struct mem_cgroup *memcg = page_memcg(head);
 	int i;
 
-	if (mem_cgroup_disabled())
+	if (mem_cgroup_disabled() || !memcg)
 		return;
 
-	for (i = 1; i < HPAGE_PMD_NR; i++) {
-		css_get(&memcg->css);
-		head[i].memcg_data = (unsigned long)memcg;
-	}
+	for (i = 1; i < nr; i++)
+		head[i].memcg_data = head->memcg_data;
+	css_get_many(&memcg->css, nr - 1);
 }
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 #ifdef CONFIG_MEMCG_SWAP
 /**