On Thu, 8 Oct 2009, Lee Schermerhorn wrote:
> From rientjes@xxxxxxxxxx Wed Oct 7 02:25:10 2009
>
From: David Rientjes <rientjes@xxxxxxxxxx>
> [PATCH 10/12] mm: clear node in N_HIGH_MEMORY and stop kswapd when all memory is offlined
>
> mm: clear node in N_HIGH_MEMORY and stop kswapd when all memory is offlined
>
> When memory is hot-removed, its node must be cleared in N_HIGH_MEMORY if
> there are no present pages left.
>
> In such a situation, kswapd must also be stopped since it has nothing
> left to do.
>
> Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
> Cc: Yasunori Goto <y-goto@xxxxxxxxxxxxxx>
> Cc: Mel Gorman <mel@xxxxxxxxx>
> Cc: Rafael J. Wysocki <rjw@xxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
Thanks for adding these, but four of five never got cc'd on the patch :)
I've added them.
> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
>
> ---
>
> include/linux/swap.h | 1 +
> mm/memory_hotplug.c | 4 ++++
> mm/vmscan.c | 28 ++++++++++++++++++++++------
> 3 files changed, 27 insertions(+), 6 deletions(-)
>
> Index: linux-2.6.31-mmotm-090925-1435/include/linux/swap.h
> ===================================================================
> --- linux-2.6.31-mmotm-090925-1435.orig/include/linux/swap.h 2009-09-28 10:10:39.000000000 -0400
> +++ linux-2.6.31-mmotm-090925-1435/include/linux/swap.h 2009-10-07 16:24:43.000000000 -0400
> @@ -273,6 +273,7 @@ extern int scan_unevictable_register_nod
> extern void scan_unevictable_unregister_node(struct node *node);
>
> extern int kswapd_run(int nid);
> +extern void kswapd_stop(int nid);
>
> #ifdef CONFIG_MMU
> /* linux/mm/shmem.c */
> Index: linux-2.6.31-mmotm-090925-1435/mm/memory_hotplug.c
> ===================================================================
> --- linux-2.6.31-mmotm-090925-1435.orig/mm/memory_hotplug.c 2009-09-28 10:10:39.000000000 -0400
> +++ linux-2.6.31-mmotm-090925-1435/mm/memory_hotplug.c 2009-10-07 16:24:43.000000000 -0400
> @@ -838,6 +838,10 @@ repeat:
>
> setup_per_zone_wmarks();
> calculate_zone_inactive_ratio(zone);
> + if (!node_present_pages(node)) {
> + node_clear_state(node, N_HIGH_MEMORY);
> + kswapd_stop(node);
> + }
>
> vm_total_pages = nr_free_pagecache_pages();
> writeback_set_ratelimit();
> Index: linux-2.6.31-mmotm-090925-1435/mm/vmscan.c
> ===================================================================
> --- linux-2.6.31-mmotm-090925-1435.orig/mm/vmscan.c 2009-09-28 10:10:43.000000000 -0400
> +++ linux-2.6.31-mmotm-090925-1435/mm/vmscan.c 2009-10-07 16:24:43.000000000 -0400
> @@ -2167,6 +2167,7 @@ static int kswapd(void *p)
> order = 0;
> for ( ; ; ) {
> unsigned long new_order;
> + int ret;
>
> prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
> new_order = pgdat->kswapd_max_order;
> @@ -2178,19 +2179,23 @@ static int kswapd(void *p)
> */
> order = new_order;
> } else {
> - if (!freezing(current))
> + if (!freezing(current) && !kthread_should_stop())
> schedule();
>
> order = pgdat->kswapd_max_order;
> }
> finish_wait(&pgdat->kswapd_wait, &wait);
>
> - if (!try_to_freeze()) {
> - /* We can speed up thawing tasks if we don't call
> - * balance_pgdat after returning from the refrigerator
> - */
> + ret = try_to_freeze();
> + if (kthread_should_stop())
> + break;
> +
> + /*
> + * We can speed up thawing tasks if we don't call balance_pgdat
> + * after returning from the refrigerator
> + */
> + if (!ret)
> balance_pgdat(pgdat, order);
> - }
> }
> return 0;
> }
> @@ -2445,6 +2450,17 @@ int kswapd_run(int nid)
> return ret;
> }
>
> +/*
> + * Called by memory hotplug when all memory in a node is offlined.
> + */
> +void kswapd_stop(int nid)
> +{
> + struct task_struct *kswapd = NODE_DATA(nid)->kswapd;
> +
> + if (kswapd)
> + kthread_stop(kswapd);
> +}
> +
> static int __init kswapd_init(void)
> {
> int nid;
>
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