linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Borislav Petkov <bp@alien8.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Christopher Lameter <cl@linux.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Elena Reshetova <elena.reshetova@intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	James Bottomley <jejb@linux.ibm.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Matthew Wilcox <willy@infradead.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Shuah Khan <shuah@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tycho Andersen <tycho@tycho.ws>, Will Deacon <will@kernel.org>,
	linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org,
	x86@kernel.org
Subject: Re: [PATCH v8 2/9] mmap: make mlock_future_check() global
Date: Thu, 12 Nov 2020 17:22:00 +0100	[thread overview]
Message-ID: <3194b507-a85f-965a-e0eb-512a79ede6a9@redhat.com> (raw)
In-Reply-To: <20201110180648.GB4758@kernel.org>

On 10.11.20 19:06, Mike Rapoport wrote:
> On Tue, Nov 10, 2020 at 06:17:26PM +0100, David Hildenbrand wrote:
>> On 10.11.20 16:14, Mike Rapoport wrote:
>>> From: Mike Rapoport <rppt@linux.ibm.com>
>>>
>>> It will be used by the upcoming secret memory implementation.
>>>
>>> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
>>> ---
>>>    mm/internal.h | 3 +++
>>>    mm/mmap.c     | 5 ++---
>>>    2 files changed, 5 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/mm/internal.h b/mm/internal.h
>>> index c43ccdddb0f6..ae146a260b14 100644
>>> --- a/mm/internal.h
>>> +++ b/mm/internal.h
>>> @@ -348,6 +348,9 @@ static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
>>>    extern void mlock_vma_page(struct page *page);
>>>    extern unsigned int munlock_vma_page(struct page *page);
>>> +extern int mlock_future_check(struct mm_struct *mm, unsigned long flags,
>>> +			      unsigned long len);
>>> +
>>>    /*
>>>     * Clear the page's PageMlocked().  This can be useful in a situation where
>>>     * we want to unconditionally remove a page from the pagecache -- e.g.,
>>> diff --git a/mm/mmap.c b/mm/mmap.c
>>> index 61f72b09d990..c481f088bd50 100644
>>> --- a/mm/mmap.c
>>> +++ b/mm/mmap.c
>>> @@ -1348,9 +1348,8 @@ static inline unsigned long round_hint_to_min(unsigned long hint)
>>>    	return hint;
>>>    }
>>> -static inline int mlock_future_check(struct mm_struct *mm,
>>> -				     unsigned long flags,
>>> -				     unsigned long len)
>>> +int mlock_future_check(struct mm_struct *mm, unsigned long flags,
>>> +		       unsigned long len)
>>>    {
>>>    	unsigned long locked, lock_limit;
>>>
>>
>> So, an interesting question is if you actually want to charge secretmem
>> pages against mlock now, or if you want a dedicated secretmem cgroup
>> controller instead?
> 
> Well, with the current implementation there are three limits an
> administrator can use to control secretmem limits: mlock, memcg and
> kernel parameter.
> 
> The kernel parameter puts a global upper limit for secretmem usage,
> memcg accounts all secretmem allocations, including the unused memory in
> large pages caching and mlock allows per task limit for secretmem
> mappings, well, like mlock does.
> 
> I didn't consider a dedicated cgroup, as it seems we already have enough
> existing knobs and a new one would be unnecessary.

To me it feels like the mlock() limit is a wrong fit for secretmem. But 
maybe there are other cases of using the mlock() limit without actually 
doing mlock() that I am not aware of (most probably :) )?

I mean, my concern is not earth shattering, this can be reworked later. 
As I said, it just feels wrong.

-- 
Thanks,

David / dhildenb


  reply	other threads:[~2020-11-12 16:22 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-10 15:14 [PATCH v8 0/9] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 1/9] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 2/9] mmap: make mlock_future_check() global Mike Rapoport
2020-11-10 17:17   ` David Hildenbrand
2020-11-10 18:06     ` Mike Rapoport
2020-11-12 16:22       ` David Hildenbrand [this message]
2020-11-12 19:08         ` Mike Rapoport
2020-11-12 20:15           ` David Hildenbrand
2020-11-15  8:26             ` Mike Rapoport
2020-11-17 15:09               ` David Hildenbrand
2020-11-17 15:58                 ` Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 3/9] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
2020-11-13 12:26   ` Catalin Marinas
2020-11-10 15:14 ` [PATCH v8 4/9] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2020-11-13 13:58   ` Matthew Wilcox
2020-11-15  8:53     ` Mike Rapoport
2020-11-13 14:06   ` Matthew Wilcox
2020-11-15  8:45     ` Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 5/9] secretmem: use PMD-size pages to amortize direct map fragmentation Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 6/9] secretmem: add memcg accounting Mike Rapoport
2020-11-13  1:35   ` Andrew Morton
2020-11-13 23:42   ` Roman Gushchin
2020-11-15  9:17     ` Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 7/9] PM: hibernate: disable when there are active secretmem users Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 8/9] arch, mm: wire up memfd_secret system call were relevant Mike Rapoport
2020-11-13 12:25   ` Catalin Marinas
2020-11-15  8:56     ` Mike Rapoport
2020-11-10 15:14 ` [PATCH v8 9/9] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport
2020-11-12 14:56 ` [PATCH v8 0/9] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=3194b507-a85f-965a-e0eb-512a79ede6a9@redhat.com \
    --to=david@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=arnd@arndb.de \
    --cc=bp@alien8.de \
    --cc=catalin.marinas@arm.com \
    --cc=cl@linux.com \
    --cc=dan.j.williams@intel.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=elena.reshetova@intel.com \
    --cc=hpa@zytor.com \
    --cc=jejb@linux.ibm.com \
    --cc=kirill@shutemov.name \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-nvdimm@lists.01.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=luto@kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mingo@redhat.com \
    --cc=mtk.manpages@gmail.com \
    --cc=palmer@dabbelt.com \
    --cc=paul.walmsley@sifive.com \
    --cc=peterz@infradead.org \
    --cc=rick.p.edgecombe@intel.com \
    --cc=rppt@kernel.org \
    --cc=rppt@linux.ibm.com \
    --cc=shuah@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tycho@tycho.ws \
    --cc=viro@zeniv.linux.org.uk \
    --cc=will@kernel.org \
    --cc=willy@infradead.org \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH v8 2/9] mmap: make mlock_future_check() global' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).