linux-kernel - Re: [PATCH v8 2/9] mmap: make mlock_future

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Date:   Tue, 10 Nov 2020 18:17:26 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Christopher Lameter <cl@...ux.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Elena Reshetova <elena.reshetova@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        James Bottomley <jejb@...ux.ibm.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Matthew Wilcox <willy@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Shuah Khan <shuah@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tycho Andersen <tycho@...ho.ws>, Will Deacon <will@...nel.org>,
        linux-api@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-riscv@...ts.infradead.org,
        x86@...nel.org
Subject: Re: [PATCH v8 2/9] mmap: make mlock_future_check() global

On 10.11.20 16:14, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@...ux.ibm.com>
> 
> It will be used by the upcoming secret memory implementation.
> 
> Signed-off-by: Mike Rapoport <rppt@...ux.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?

-- 
Thanks,

David / dhildenb