[PATCH] mm: numa: Initialse numa balancing after jump label initialisation

[PATCH] mm: numa: Initialse numa balancing after jump label initialisation

[Mel Gorman]

The command line parsing takes place before jump labels are initialised which
generates a warning if numa_balancing= is specified and CONFIG_JUMP_LABEL
is set. On older kernls before commit c4b2c0c5 (static_key: WARN on
usage before jump_label_init was called) the kernel would have crashed.
This patch enables automatic numa balancing later in the initialisation
process if numa_balancing= is specified.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Stable <stable@vger.kernel.org>
---
 mm/mempolicy.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 0cd2c4d..5223684 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2657,7 +2657,7 @@ void mpol_free_shared_policy(struct shared_policy *p)
 }
 
 #ifdef CONFIG_NUMA_BALANCING
-static bool __initdata numabalancing_override;
+static int __initdata numabalancing_override;
 
 static void __init check_numabalancing_enable(void)
 {
@@ -2666,9 +2666,14 @@ static void __init check_numabalancing_enable(void)
 	if (IS_ENABLED(CONFIG_NUMA_BALANCING_DEFAULT_ENABLED))
 		numabalancing_default = true;
 
+	/* Parsed by setup_numabalancing. override == 1 enables, -1 disables */
+	if (numabalancing_override)
+		set_numabalancing_state(numabalancing_override == 1);
+
 	if (nr_node_ids > 1 && !numabalancing_override) {
-		printk(KERN_INFO "Enabling automatic NUMA balancing. "
-			"Configure with numa_balancing= or sysctl");
+		printk(KERN_INFO "%s automatic NUMA balancing. "
+			"Configure with numa_balancing= or sysctl",
+			numabalancing_default ? "Enabling" : "Disabling");
 		set_numabalancing_state(numabalancing_default);
 	}
 }
@@ -2678,13 +2683,12 @@ static int __init setup_numabalancing(char *str)
 	int ret = 0;
 	if (!str)
 		goto out;
-	numabalancing_override = true;
 
 	if (!strcmp(str, "enable")) {
-		set_numabalancing_state(true);
+		numabalancing_override = 1;
 		ret = 1;
 	} else if (!strcmp(str, "disable")) {
-		set_numabalancing_state(false);
+		numabalancing_override = -1;
 		ret = 1;
 	}
 out:

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Re: [PATCH] mm: numa: Initialse numa balancing after jump label initialisation

[Rik van Riel]

On 01/27/2014 10:51 AM, Mel Gorman wrote:
> The command line parsing takes place before jump labels are initialised which
> generates a warning if numa_balancing= is specified and CONFIG_JUMP_LABEL
> is set. On older kernls before commit c4b2c0c5 (static_key: WARN on
> usage before jump_label_init was called) the kernel would have crashed.
> This patch enables automatic numa balancing later in the initialisation
> process if numa_balancing= is specified.
> 
> Signed-off-by: Mel Gorman <mgorman@suse.de>
> Cc: Stable <stable@vger.kernel.org>

Acked-by: Rik van Riel <riel@redhat.com>

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Re: [PATCH] mm: numa: Initialse numa balancing after jump label initialisation

[Andrew Morton]

On Mon, 27 Jan 2014 15:51:27 +0000 Mel Gorman <mgorman@suse.de> wrote:

> The command line parsing takes place before jump labels are initialised which
> generates a warning if numa_balancing= is specified and CONFIG_JUMP_LABEL
> is set. On older kernls before commit c4b2c0c5 (static_key: WARN on
> usage before jump_label_init was called) the kernel would have crashed.
> This patch enables automatic numa balancing later in the initialisation
> process if numa_balancing= is specified.
> 
> ...
>
> @@ -2666,9 +2666,14 @@ static void __init check_numabalancing_enable(void)
>  	if (IS_ENABLED(CONFIG_NUMA_BALANCING_DEFAULT_ENABLED))
>  		numabalancing_default = true;
>  
> +	/* Parsed by setup_numabalancing. override == 1 enables, -1 disables */
> +	if (numabalancing_override)
> +		set_numabalancing_state(numabalancing_override == 1);
> +
>  	if (nr_node_ids > 1 && !numabalancing_override) {
> -		printk(KERN_INFO "Enabling automatic NUMA balancing. "
> -			"Configure with numa_balancing= or sysctl");
> +		printk(KERN_INFO "%s automatic NUMA balancing. "
> +			"Configure with numa_balancing= or sysctl",
> +			numabalancing_default ? "Enabling" : "Disabling");
>  		set_numabalancing_state(numabalancing_default);
>  	}
>  }

Current mainline is a bit different from this:

		printk(KERN_INFO "Enabling automatic NUMA balancing. "
			"Configure with numa_balancing= or the kernel.numa_balancing sysctl");

So this won't apply as-is to -stable.

I assume you suggested the -stable backport to fix the
it-crashes-before-c4b2c0c5 thing, so it isn't really needed in 3.12.x.

Or something.  Please sort all that out when Greg comes back with
a hey-that-didnt-apply.

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Re: [PATCH] mm: numa: Initialse numa balancing after jump label initialisation

[Mel Gorman]

On Mon, Jan 27, 2014 at 02:43:36PM -0800, Andrew Morton wrote:
> On Mon, 27 Jan 2014 15:51:27 +0000 Mel Gorman <mgorman@suse.de> wrote:
> 
> > The command line parsing takes place before jump labels are initialised which
> > generates a warning if numa_balancing= is specified and CONFIG_JUMP_LABEL
> > is set. On older kernls before commit c4b2c0c5 (static_key: WARN on
> > usage before jump_label_init was called) the kernel would have crashed.
> > This patch enables automatic numa balancing later in the initialisation
> > process if numa_balancing= is specified.
> > 
> > ...
> >
> > @@ -2666,9 +2666,14 @@ static void __init check_numabalancing_enable(void)
> >  	if (IS_ENABLED(CONFIG_NUMA_BALANCING_DEFAULT_ENABLED))
> >  		numabalancing_default = true;
> >  
> > +	/* Parsed by setup_numabalancing. override == 1 enables, -1 disables */
> > +	if (numabalancing_override)
> > +		set_numabalancing_state(numabalancing_override == 1);
> > +
> >  	if (nr_node_ids > 1 && !numabalancing_override) {
> > -		printk(KERN_INFO "Enabling automatic NUMA balancing. "
> > -			"Configure with numa_balancing= or sysctl");
> > +		printk(KERN_INFO "%s automatic NUMA balancing. "
> > +			"Configure with numa_balancing= or sysctl",
> > +			numabalancing_default ? "Enabling" : "Disabling");
> >  		set_numabalancing_state(numabalancing_default);
> >  	}
> >  }
> 
> Current mainline is a bit different from this:
> 
> 		printk(KERN_INFO "Enabling automatic NUMA balancing. "
> 			"Configure with numa_balancing= or the kernel.numa_balancing sysctl");
> 
> So this won't apply as-is to -stable.
> 

That's ok.

> I assume you suggested the -stable backport to fix the
> it-crashes-before-c4b2c0c5 thing, so it isn't really needed in 3.12.x.
> 

I am recommending this patch for -stable because 3.12.x crashes. c4b2c0c5
prevents a crash but it is still the case that the parameter is not handled
properly so backporting c4b2c0c5 is not a suitable alternative.

> Or something.  Please sort all that out when Greg comes back with
> a hey-that-didnt-apply.

I will.

-- 
Mel Gorman
SUSE Labs

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