Re: [Suspend2][ 07/13] [Suspend2] Page_alloc paranoia.

[Nick Piggin <nickpiggin@yahoo.com.au>]

Nigel Cunningham wrote:
> Add paranoia to the page_alloc code to ensure we don't start page reclaim
> during suspending.

Nack. Set PF_MEMALLOC if you must.

> Signed-off-by: Nigel Cunningham <nigel@suspend2.net>
>
>  mm/page_alloc.c |   18 +++++++++++++-----
>  1 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 253a450..838ae19 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -25,6 +25,7 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/suspend.h>
> +#include <linux/freezer.h>
>  #include <linux/pagevec.h>
>  #include <linux/blkdev.h>
>  #include <linux/slab.h>
> @@ -37,6 +38,7 @@
>  #include <linux/nodemask.h>
>  #include <linux/vmalloc.h>
>  #include <linux/mempolicy.h>
> +#include "../kernel/power/pageflags.h"
>  
>  #include <asm/tlbflush.h>
>  #include <asm/div64.h>
> @@ -905,7 +907,8 @@ get_page_from_freelist(gfp_t gfp_mask, u
>  			else
>  				mark = (*z)->pages_high;
>  			if (!zone_watermark_ok(*z, order, mark,
> -				    classzone_idx, alloc_flags))
> +				    classzone_idx, alloc_flags) &&
> +			    likely(!test_freezer_state(FREEZER_ON)))
>  				if (!zone_reclaim_mode ||
>  				    !zone_reclaim(*z, gfp_mask, order))
>  					continue;
> @@ -950,10 +953,12 @@ restart:
>  	if (page)
>  		goto got_pg;
>  
> -	do {
> -		if (cpuset_zone_allowed(*z, gfp_mask|__GFP_HARDWALL))
> -			wakeup_kswapd(*z, order);
> -	} while (*(++z));
> +	if (likely(!test_freezer_state(FREEZER_ON))) {
> +		do {
> +			if (cpuset_zone_allowed(*z, gfp_mask|__GFP_HARDWALL))
> +				wakeup_kswapd(*z, order);
> +		} while (*(++z));
> +	}
>  
>  	/*
>  	 * OK, we're below the kswapd watermark and have kicked background
> @@ -997,6 +1002,7 @@ nofail_alloc:
>  			if (page)
>  				goto got_pg;
>  			if (gfp_mask & __GFP_NOFAIL) {
> +				BUG_ON(unlikely(test_freezer_state(FREEZING_COMPLETE)));
>  				blk_congestion_wait(WRITE, HZ/50);
>  				goto nofail_alloc;
>  			}
> @@ -1009,6 +1015,8 @@ nofail_alloc:
>  		goto nopage;
>  
>  rebalance:
> +	BUG_ON(unlikely(test_freezer_state(FREEZER_ON)));
> +
>  	cond_resched();
>  
>  	/* We now go into synchronous reclaim */
>
> --
> Nigel Cunningham		nigel at suspend2 dot net

--
SUSE Labs, Novell Inc.
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