Re: [PATCH 03/31] mm: expose gfp_to_alloc_flags()
From: David Rientjes <rientjes@google.com>
Date: 2009-10-02 09:30:27
Also in:
linux-mm, lkml
Subsystem:
memory management, memory management - core, memory management - page allocator, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Vlastimil Babka, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2009-10-02 · Re: [PATCH 03/31] mm: expose gfp_to_alloc_flags() · Suresh Jayaraman <hidden>
- 2009-10-01 · Re: [PATCH 03/31] mm: expose gfp_to_alloc_flags() · David Rientjes <rientjes@google.com>
- 2009-10-01 · [PATCH 03/31] mm: expose gfp_to_alloc_flags() · Suresh Jayaraman <hidden>
On Fri, 2 Oct 2009, Neil Brown wrote:
So something like this? Then change every occurrence of + if (!(gfp_to_alloc_flags(gfpflags) & ALLOC_NO_WATERMARKS)) to + if (!(gfp_has_no_watermarks(gfpflags))) ??
No, it's not even necessary to call gfp_to_alloc_flags() at all, just create a globally exported function such as can_alloc_use_reserves() and use it in gfp_to_alloc_flags(). [ Using 'p' in gfp_to_alloc_flags() is actually wrong since test_thread_flag() only works on current anyway, so it would be inconsistent if p were set to anything other than current; we can get rid of that auto variable. ] Something like the following, which you can fold into this patch proposal and modify later for GFP_MEMALLOC. Signed-off-by: David Rientjes <rientjes@google.com> ---
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 557bdad..7dd62a0 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h@@ -265,6 +265,8 @@ static inline void arch_free_page(struct page *page, int order) { } static inline void arch_alloc_page(struct page *page, int order) { } #endif +int can_alloc_use_reserves(void); + struct page * __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist, nodemask_t *nodemask);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bf72055..cf1d765 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c@@ -1744,10 +1744,19 @@ void wake_all_kswapd(unsigned int order, struct zonelist *zonelist, wakeup_kswapd(zone, order); } +/* + * Does the current context allow the allocation to utilize memory reserves + * by ignoring watermarks for all zones? + */ +int can_alloc_use_reserves(void) +{ + return !in_interrupt() && ((current->flags & PF_MEMALLOC) || + unlikely(test_thread_flag(TIF_MEMDIE))); +} + static inline int gfp_to_alloc_flags(gfp_t gfp_mask) { - struct task_struct *p = current; int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET; const gfp_t wait = gfp_mask & __GFP_WAIT;
@@ -1769,15 +1778,12 @@ gfp_to_alloc_flags(gfp_t gfp_mask) * See also cpuset_zone_allowed() comment in kernel/cpuset.c. */ alloc_flags &= ~ALLOC_CPUSET; - } else if (unlikely(rt_task(p))) + } else if (unlikely(rt_task(current))) alloc_flags |= ALLOC_HARDER; - if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) { - if (!in_interrupt() && - ((p->flags & PF_MEMALLOC) || - unlikely(test_thread_flag(TIF_MEMDIE)))) + if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) + if (can_alloc_use_reserves()) alloc_flags |= ALLOC_NO_WATERMARKS; - } return alloc_flags; } --
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