Re: [PATCH 2/4] (CMA_AGGRESSIVE) Add argument hibernation to function shrink_all_memory

From: Rafael J. Wysocki
Date: Thu Oct 16 2014 - 04:25:14 EST


[CC list trimmed]

On Thursday, October 16, 2014 11:35:49 AM Hui Zhu wrote:
> Function shrink_all_memory try to free `nr_to_reclaim' of memory.
> CMA_AGGRESSIVE_SHRINK function will call this functon to free `nr_to_reclaim' of
> memory. It need different scan_control with current caller function
> hibernate_preallocate_memory.
>
> If hibernation is true, the caller is hibernate_preallocate_memory.
> if not, the caller is CMA alloc function.
>
> Signed-off-by: Hui Zhu <zhuhui@xxxxxxxxxx>
> ---
> include/linux/swap.h | 3 ++-
> kernel/power/snapshot.c | 2 +-
> mm/vmscan.c | 19 +++++++++++++------
> 3 files changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 37a585b..9f2cb43 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -335,7 +335,8 @@ extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
> gfp_t gfp_mask, bool noswap,
> struct zone *zone,
> unsigned long *nr_scanned);
> -extern unsigned long shrink_all_memory(unsigned long nr_pages);
> +extern unsigned long shrink_all_memory(unsigned long nr_pages,
> + bool hibernation);
> extern int vm_swappiness;
> extern int remove_mapping(struct address_space *mapping, struct page *page);
> extern unsigned long vm_total_pages;
> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> index 791a618..a00fc35 100644
> --- a/kernel/power/snapshot.c
> +++ b/kernel/power/snapshot.c
> @@ -1657,7 +1657,7 @@ int hibernate_preallocate_memory(void)
> * NOTE: If this is not done, performance will be hurt badly in some
> * test cases.
> */
> - shrink_all_memory(saveable - size);
> + shrink_all_memory(saveable - size, true);

Instead of doing this, can you please define

__shrink_all_memory()

that will take the appropriate struct scan_control as an argument and
then define two wrappers around that, one for hibernation and one for CMA?

The way you did it opens a field for bugs caused by passing a wrong value
as the second argument.

>
> /*
> * The number of saveable pages in memory was too high, so apply some
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index dcb4707..fdcfa30 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -3404,7 +3404,7 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
> wake_up_interruptible(&pgdat->kswapd_wait);
> }
>
> -#ifdef CONFIG_HIBERNATION
> +#if defined CONFIG_HIBERNATION || defined CONFIG_CMA_AGGRESSIVE
> /*
> * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
> * freed pages.
> @@ -3413,22 +3413,29 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
> * LRU order by reclaiming preferentially
> * inactive > active > active referenced > active mapped
> */
> -unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
> +unsigned long shrink_all_memory(unsigned long nr_to_reclaim, bool hibernation)
> {
> struct reclaim_state reclaim_state;
> struct scan_control sc = {
> .nr_to_reclaim = nr_to_reclaim,
> - .gfp_mask = GFP_HIGHUSER_MOVABLE,
> .priority = DEF_PRIORITY,
> - .may_writepage = 1,
> .may_unmap = 1,
> .may_swap = 1,
> - .hibernation_mode = 1,
> };
> struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
> struct task_struct *p = current;
> unsigned long nr_reclaimed;
>
> + if (hibernation) {
> + sc.hibernation_mode = 1;
> + sc.may_writepage = 1;
> + sc.gfp_mask = GFP_HIGHUSER_MOVABLE;
> + } else {
> + sc.hibernation_mode = 0;
> + sc.may_writepage = !laptop_mode;
> + sc.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_HIGHMEM;
> + }
> +
> p->flags |= PF_MEMALLOC;
> lockdep_set_current_reclaim_state(sc.gfp_mask);
> reclaim_state.reclaimed_slab = 0;
> @@ -3442,7 +3449,7 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
>
> return nr_reclaimed;
> }
> -#endif /* CONFIG_HIBERNATION */
> +#endif /* CONFIG_HIBERNATION || CONFIG_CMA_AGGRESSIVE */
>
> /* It's optimal to keep kswapds on the same CPUs as their memory, but
> not required for correctness. So if the last cpu in a node goes
>

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/