Re: [patch v2] mm, pcp: allow restoring percpu_pagelist_fraction default

From: Oleg Drokin
Date: Wed Jun 04 2014 - 20:47:04 EST


Hello!

On Jun 4, 2014, at 8:34 PM, David Rientjes wrote:
> @@ -5850,23 +5851,39 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write,
> void __user *buffer, size_t *length, loff_t *ppos)
> {
> struct zone *zone;
> - unsigned int cpu;
> + int old_percpu_pagelist_fraction;
> int ret;
>
> + mutex_lock(&pcp_batch_high_lock);
> + old_percpu_pagelist_fraction = percpu_pagelist_fraction;
> +
> ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
> - if (!write || (ret < 0))
> - return ret;
> + if (!write || ret < 0)
> + goto out;
> +
> + /* Sanity checking to avoid pcp imbalance */
> + if (percpu_pagelist_fraction &&
> + percpu_pagelist_fraction < MIN_PERCPU_PAGELIST_FRACTION) {
> + percpu_pagelist_fraction = old_percpu_pagelist_fraction;
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + ret = 0;

Minor nitpick I guess, but ret cannot be anything but 0 here I think (until somebody changes the way proc_dointvec_minmax for write=true operates)?

The patch is good otherwise.

Thanks.--
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