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Message-ID: <CALCETrUT3jCVt0DXbdvwSNtszGmqhk2tnCcZ2TkhMftHofTdRQ@mail.gmail.com>
Date: Fri, 17 Jun 2016 15:18:18 -0700
From: Andy Lutomirski <luto@...capital.net>
To: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Andy Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, linux-arch <linux-arch@...r.kernel.org>,
Borislav Petkov <bp@...en8.de>, Nadav Amit <nadav.amit@...il.com>, Kees Cook <keescook@...omium.org>,
Brian Gerst <brgerst@...il.com>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>,
Linus Torvalds <torvalds@...ux-foundation.org>, Jann Horn <jann@...jh.net>,
Heiko Carstens <heiko.carstens@...ibm.com>, Vladimir Davydov <vdavydov@...tuozzo.com>,
Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH v2 05/13] mm: Move memcg stack accounting to account_kernel_stack
On Fri, Jun 17, 2016 at 1:55 PM, Josh Poimboeuf <jpoimboe@...hat.com> 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@...tuozzo.com>
>> Cc: Johannes Weiner <hannes@...xchg.org>
>> Cc: Michal Hocko <mhocko@...nel.org>
>> Cc: linux-mm@...ck.org
>> Signed-off-by: Andy Lutomirski <luto@...nel.org>
>> ---
>> 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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