On Fri, Jun 17, 2016 at 1:55 PM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> On Fri, Jun 17, 2016 at 01:00:41PM -0700, Andy Lutomirski wrote:
>> We should account for stacks regardless of stack size. Move it into
>> account_kernel_stack.
>>
>> Fixes: 12580e4b54ba8 ("mm: memcontrol: report kernel stack usage in cgroup2 memory.stat")
>> Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
>> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
>> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
>> Cc: linux-mm@xxxxxxxxx
>> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
>> ---
>> kernel/fork.c | 15 ++++++---------
>> 1 file changed, 6 insertions(+), 9 deletions(-)
>>
>> diff --git a/kernel/fork.c b/kernel/fork.c
>> index be7f006af727..cd2abe6e4e41 100644
>> --- a/kernel/fork.c
>> +++ b/kernel/fork.c
>> @@ -165,20 +165,12 @@ static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
>> struct page *page = alloc_kmem_pages_node(node, THREADINFO_GFP,
>> THREAD_SIZE_ORDER);
>>
>> - if (page)
>> - memcg_kmem_update_page_stat(page, MEMCG_KERNEL_STACK,
>> - 1 << THREAD_SIZE_ORDER);
>> -
>> return page ? page_address(page) : NULL;
>> }
>>
>> static inline void free_thread_info(struct thread_info *ti)
>> {
>> - struct page *page = virt_to_page(ti);
>> -
>> - memcg_kmem_update_page_stat(page, MEMCG_KERNEL_STACK,
>> - -(1 << THREAD_SIZE_ORDER));
>> - __free_kmem_pages(page, THREAD_SIZE_ORDER);
>> + free_kmem_pages((unsigned long)ti, THREAD_SIZE_ORDER);
>> }
>> # else
>> static struct kmem_cache *thread_info_cache;
>> @@ -227,6 +219,11 @@ static void account_kernel_stack(struct thread_info *ti, int account)
>>
>> mod_zone_page_state(zone, NR_KERNEL_STACK_KB,
>> THREAD_SIZE / 1024 * account);
>> +
>> + /* All stack pages belong to the same memcg. */
>> + memcg_kmem_update_page_stat(
>> + virt_to_page(ti), MEMCG_KERNEL_STACK,
>> + account * (THREAD_SIZE / PAGE_SIZE));
>> }
>
> Won't this be broken in the case where THREAD_SIZE < PAGE_SIZE?
In my defense, it was broken before this change, too. Sigh. I'll
change this to count in KiB too.
As far as I can tell, this thing is used for display only.
--Andy
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