On Mon, 14 Nov 2011, Mel Gorman wrote:
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 9dd443d..5402897 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -127,6 +127,20 @@ void pm_restrict_gfp_mask(void)
> saved_gfp_mask = gfp_allowed_mask;
> gfp_allowed_mask &= ~GFP_IOFS;
> }
> +
> +static bool pm_suspending(void)
> +{
> + if ((gfp_allowed_mask & GFP_IOFS) == GFP_IOFS)
> + return false;
> + return true;
> +}
> +
> +#else
> +
> +static bool pm_suspending(void)
> +{
> + return false;
> +}
> #endif /* CONFIG_PM_SLEEP */
>
> #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
> @@ -2214,6 +2228,14 @@ rebalance:
>
> goto restart;
> }
> +
> + /*
> + * Suspend converts GFP_KERNEL to __GFP_WAIT which can
> + * prevent reclaim making forward progress without
> + * invoking OOM. Bail if we are suspending
> + */
> + if (pm_suspending())
> + goto nopage;
> }
>
> /* Check if we should retry the allocation */
This allows all __GFP_NOFAIL allocations to fail while
pm_restrict_gfp_mask() is in effect, so I disagree with this unless it is
moved into the should_alloc_retry() logic. If you pass did_some_progress
into that function and then moved the check for __GFP_NOFAIL right under
the check for __GFP_NORETRY and checked for pm_suspending() there (and
before the check for PAGE_ALLOC_COSTLY_ORDER) then it would allow the
infinite loop for __GFP_NOFAIL which is required if __GFP_WAIT.
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