Re: [linux-pm] [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: Memory allocations in .suspend became very unreliable)

KOSAKI Motohiro
2010-01-18T02:20:40Z

> Index: linux-2.6/mm/page_alloc.c
> ===================================================================
> --- linux-2.6.orig/mm/page_alloc.c
> +++ linux-2.6/mm/page_alloc.c
> @@ -1963,10 +1963,13 @@ __alloc_pages_nodemask(gfp_t gfp_mask, u
> page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
> zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET,
> preferred_zone, migratetype);
> - if (unlikely(!page))
> + if (unlikely(!page)) {
> + mm_lock_suspend(gfp_mask);
> page = __alloc_pages_slowpath(gfp_mask, order,
> zonelist, high_zoneidx, nodemask,
> preferred_zone, migratetype);
> + mm_unlock_suspend(gfp_mask);
> + }
>
> trace_mm_page_alloc(page, order, gfp_mask, migratetype);
> return page;

I think we don't need read side lock at all. generally, no lock might makes race.
But in this case, changing gfp_allowed_mask and nvidia suspend method should be
serialized higher level. Why the above two code need to run concurrently?