Re: [RFC PATCH 1/2] mm, vmstat: hide /proc/pagetypeinfo from normal users

[David Rientjes]

On Wed, 23 Oct 2019, Michal Hocko wrote:

> From: Michal Hocko <mhocko@xxxxxxxx>
> 
> /proc/pagetypeinfo is a debugging tool to examine internal page
> allocator state wrt to fragmentation. It is not very useful for
> any other use so normal users really do not need to read this file.
> 
> Waiman Long has noticed that reading this file can have negative side
> effects because zone->lock is necessary for gathering data and that
> a) interferes with the page allocator and its users and b) can lead to
> hard lockups on large machines which have very long free_list.
> 
> Reduce both issues by simply not exporting the file to regular users.
> 
> Reported-by: Waiman Long <longman@xxxxxxxxxx>
> Cc: stable
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>

Acked-by: David Rientjes <rientjes@xxxxxxxxxx>