linux-kernel - Re: [PATCH v8 18/27] mm: Introduce do_mmap

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Date:   Mon, 19 Aug 2019 18:02:00 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Yu-cheng Yu <yu-cheng.yu@...el.com>
Cc:     x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-api@...r.kernel.org,
        Arnd Bergmann <arnd@...db.de>,
        Andy Lutomirski <luto@...capital.net>,
        Balbir Singh <bsingharora@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Eugene Syromiatnikov <esyr@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        "H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
        Peter Zijlstra <peterz@...radead.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>,
        Dave Martin <Dave.Martin@....com>
Subject: Re: [PATCH v8 18/27] mm: Introduce do_mmap_locked()

On Tue, Aug 13, 2019 at 01:52:16PM -0700, Yu-cheng Yu wrote:
> There are a few places that need do_mmap() with mm->mmap_sem held.
> Create an in-line function for that.
> 
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@...el.com>
> ---
>  include/linux/mm.h | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index bc58585014c9..275c385f53c6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2394,6 +2394,24 @@ static inline void mm_populate(unsigned long addr, unsigned long len)
>  static inline void mm_populate(unsigned long addr, unsigned long len) {}
>  #endif
>  
> +static inline unsigned long do_mmap_locked(struct file *file,
> +	unsigned long addr, unsigned long len, unsigned long prot,
> +	unsigned long flags, vm_flags_t vm_flags, struct list_head *uf)
> +{
> +	struct mm_struct *mm = current->mm;
> +	unsigned long populate;
> +
> +	down_write(&mm->mmap_sem);
> +	addr = do_mmap(file, addr, len, prot, flags, vm_flags, 0,
> +		       &populate, uf);
> +	up_write(&mm->mmap_sem);
> +
> +	if (populate)
> +		mm_populate(addr, populate);
> +
> +	return addr;
> +}

Any reason not to put this in cet.c, as suggested by PeterZ?  All of the
calls from CET have identical params except for @len, e.g. you can add
'static unsigned long cet_mmap(unsigned long len)' and bury most of the
copy-paste code in there.

https://lkml.kernel.org/r/20190607074707.GD3463@hirez.programming.kicks-ass.net

> +
>  /* These take the mm semaphore themselves */
>  extern int __must_check vm_brk(unsigned long, unsigned long);
>  extern int __must_check vm_brk_flags(unsigned long, unsigned long, unsigned long);
> -- 
> 2.17.1
>