linux-kernel - Re: [PATCH] mm, vmstat: Make sure mutex is a global static

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Date:   Wed, 8 Nov 2017 15:20:43 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Ying Huang <ying.huang@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm, vmstat: Make sure mutex is a global static

On Wed 08-11-17 08:43:44, Vlastimil Babka wrote:
> On 11/07/2017 10:38 PM, Kees Cook wrote:
[...]
> > +static DEFINE_MUTEX(vm_numa_stat_lock);
> > +
> >  int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
> >  		void __user *buffer, size_t *length, loff_t *ppos)
> >  {
> >  	int ret, oldval;
> > -	DEFINE_MUTEX(vm_numa_stat_lock);
> 
> Yeah it was Michal who suggested scoping the mutex here instead of
> global scope, but I think he didn't mean to remove the 'static'
> qualifier, and we both missed that in the review :(
> So the scope under sysctl_vm_numa_stat_handler() should be okay, just
> with the 'static' added.

exactly! Sorry that I've missed the missing static and thanks for
catching that Kees.

-- 
Michal Hocko
SUSE Labs