linux-kernel - Re: [PATCH 1/4] ipc/shm: do not check for MAP

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Date:   Thu, 9 Feb 2017 18:15:14 -0800 (PST)
From:   Hugh Dickins <hughd@...gle.com>
To:     Davidlohr Bueso <dave@...olabs.net>
cc:     akpm@...ux-foundation.org, manfred@...orfullife.com,
        linux-kernel@...r.kernel.org, Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH 1/4] ipc/shm: do not check for MAP_POPULATE

On Thu, 9 Feb 2017, Davidlohr Bueso wrote:

> We do not support prefaulting functionality in sysv shm,
> nor MAP_NONBLOCK for that matter. Drop the pointless check
> for populate in do_shmat().

I haven't checked, but are you sure that "populated" does nothing
when the attacher had previously called mlockall(MCL_FUTURE)?

Hugh

> 
> Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
> ---
>  ipc/shm.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/ipc/shm.c b/ipc/shm.c
> index 06ea9ef7f54a..6b3769967789 100644
> --- a/ipc/shm.c
> +++ b/ipc/shm.c
> @@ -1234,8 +1234,6 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg,
>  		err = (long)addr;
>  invalid:
>  	up_write(&current->mm->mmap_sem);
> -	if (populate)
> -		mm_populate(addr, populate);
>  
>  out_fput:
>  	fput(file);
> -- 
> 2.6.6