Re: [PATCH] mremap.2: Add note about mremap with locked areas

[Michal Hocko <mhocko@kernel.org>]

On Fri 28-08-15 14:42:52, Eric B Munson wrote:
> When mremap() is used to move or expand a mapping that is locked with
> mlock() or equivalent it will attempt to populate the new area.
> However, like mmap(MAP_LOCKED), mremap() will not fail if the area
> cannot be populated.  Also like mmap(MAP_LOCKED) this might come as a
> surprise to users and should be noted.
> 
> Signed-off-by: Eric B Munson <emunson@akamai.com>
> Cc: Michal Hocko <mhocko@suse.cz>

Acked-by: Michal Hocko <mhocko@suse.com>

Thank you for following on this.

> Cc: David Rientjes <rientjes@google.com>
> Cc: linux-man@vger.kernel.org
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  man2/mremap.2 | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/man2/mremap.2 b/man2/mremap.2
> index 071adb5..cf884e6 100644
> --- a/man2/mremap.2
> +++ b/man2/mremap.2
> @@ -196,6 +196,17 @@ and the prototype for
>  did not allow for the
>  .I new_address
>  argument.
> +
> +If
> +.BR mremap ()
> +is used to move or expand an area locked with
> +.BR mlock (2)
> +or equivalent, the
> +.BR mremap ()
> +call will make a best effort to populate the new area but will not fail
> +with
> +.B ENOMEM
> +if the area cannot be populated.
>  .SH SEE ALSO
>  .BR brk (2),
>  .BR getpagesize (2),
> -- 
> 1.9.1

-- 
Michal Hocko
SUSE Labs

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