Messages in this thread | | | Date | Tue, 15 Nov 2011 13:40:42 -0800 (PST) | From | David Rientjes <> | Subject | Re: [PATCH] mm: avoid livelock on !__GFP_FS allocations |
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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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