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From: Rafael Aquini <aquini@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Waiman Long <longman@redhat.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Roman Gushchin <guro@fb.com>, Vlastimil Babka <vbabka@suse.cz>,
	Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
	Jann Horn <jannh@google.com>, Song Liu <songliubraving@fb.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: Re: [RFC PATCH 1/2] mm, vmstat: hide /proc/pagetypeinfo from normal users
Date: Wed, 23 Oct 2019 11:10:05 -0400	[thread overview]
Message-ID: <20191023151005.GE22601@optiplex-lnx> (raw)
In-Reply-To: <20191023102737.32274-2-mhocko@kernel.org>

On Wed, Oct 23, 2019 at 12:27:36PM +0200, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> /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@redhat.com>
> Cc: stable
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  mm/vmstat.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 6afc892a148a..4e885ecd44d1 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1972,7 +1972,7 @@ void __init init_mm_internals(void)
>  #endif
>  #ifdef CONFIG_PROC_FS
>  	proc_create_seq("buddyinfo", 0444, NULL, &fragmentation_op);
> -	proc_create_seq("pagetypeinfo", 0444, NULL, &pagetypeinfo_op);
> +	proc_create_seq("pagetypeinfo", 0400, NULL, &pagetypeinfo_op);
>  	proc_create_seq("vmstat", 0444, NULL, &vmstat_op);
>  	proc_create_seq("zoneinfo", 0444, NULL, &zoneinfo_op);
>  #endif
> -- 
> 2.20.1
>
 
Acked-by: Rafael Aquini <aquini@redhat.com>


  parent reply	other threads:[~2019-10-23 15:10 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-22 16:21 [PATCH] mm/vmstat: Reduce zone lock hold time when reading /proc/pagetypeinfo Waiman Long
2019-10-22 16:57 ` Michal Hocko
2019-10-22 18:00   ` Waiman Long
2019-10-22 18:40     ` Waiman Long
2019-10-23  0:52       ` David Rientjes
2019-10-23  0:52         ` David Rientjes
2019-10-23  8:31   ` Mel Gorman
2019-10-23  9:04     ` Michal Hocko
2019-10-23  9:56       ` Mel Gorman
2019-10-23 10:27         ` [RFC PATCH 0/2] " Michal Hocko
2019-10-23 10:27           ` [RFC PATCH 1/2] mm, vmstat: hide /proc/pagetypeinfo from normal users Michal Hocko
2019-10-23 13:13             ` Mel Gorman
2019-10-23 13:27             ` Vlastimil Babka
2019-10-23 14:52             ` Waiman Long
2019-10-23 15:10             ` Rafael Aquini [this message]
2019-10-23 16:15             ` Vlastimil Babka
2019-10-24 19:01             ` David Rientjes
2019-10-24 19:01               ` David Rientjes
2019-10-23 10:27           ` [RFC PATCH 2/2] mm, vmstat: reduce zone->lock holding time by /proc/pagetypeinfo Michal Hocko
2019-10-23 13:15             ` Mel Gorman
2019-10-23 13:32             ` Vlastimil Babka
2019-10-23 13:37               ` Michal Hocko
2019-10-23 13:48                 ` Vlastimil Babka
2019-10-23 14:31                   ` Michal Hocko
2019-10-23 16:20                     ` Vlastimil Babka
2019-10-23 13:46               ` Rafael Aquini
2019-10-23 14:56             ` Waiman Long
2019-10-23 15:21               ` Waiman Long
2019-10-23 16:10               ` Michal Hocko
2019-10-23 16:17                 ` Waiman Long
2019-10-23 16:21                   ` Waiman Long
2019-10-23 16:15             ` Vlastimil Babka
2019-10-23 16:41             ` Michal Hocko
2019-10-23 16:47               ` Waiman Long
2019-10-23 17:34             ` [PATCH 1/2] mm, vmstat: Release zone lock more frequently when reading /proc/pagetypeinfo Waiman Long
2019-10-23 18:01               ` Michal Hocko
2019-10-23 18:14                 ` Waiman Long
2019-10-23 20:02                   ` Michal Hocko
2019-10-23 17:34             ` [PATCH 2/2] mm, vmstat: List total free blocks for each order in /proc/pagetypeinfo Waiman Long
2019-10-23 18:02               ` Michal Hocko
2019-10-23 18:07                 ` Waiman Long
2019-10-24  8:20           ` [RFC PATCH 0/2] mm/vmstat: Reduce zone lock hold time when reading /proc/pagetypeinfo Michal Hocko
2019-10-24 16:16             ` Waiman Long
2019-10-23 12:42         ` [PATCH] " Qian Cai
2019-10-23 13:25         ` Vlastimil Babka
2019-10-22 21:59 ` Andrew Morton
2019-10-23  6:15   ` Michal Hocko
2019-10-23 14:30   ` Waiman Long
2019-10-23 14:48     ` Qian Cai
2019-10-23 14:48       ` Qian Cai
2019-10-23 15:01       ` Waiman Long
2019-10-23 15:05         ` Qian Cai
2019-10-23 15:05           ` Qian Cai
2019-10-23 22:30         ` Andrew Morton
2019-10-24  5:33           ` Qian Cai
2019-10-24  7:42             ` Michal Hocko
2019-10-24 11:11               ` Qian Cai
2019-10-24 13:38                 ` Michal Hocko
2019-10-24 14:55                   ` Qian Cai
2019-10-24  3:33         ` Feng Tang
2019-10-24  4:34           ` Qian Cai
2019-10-24  5:34             ` Feng Tang
2019-10-24 10:51               ` Qian Cai
2019-10-25  1:38                 ` Feng Tang
2019-10-23 15:03       ` Rafael Aquini
2019-10-23 15:51         ` Qian Cai
2019-10-23 15:51           ` Qian Cai

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