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Subject[PATCH 01/33] mm: gfp_to_alloc_flags()
Factor out the gfp to alloc_flags mapping so it can be used in other places.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
mm/internal.h | 11 ++++++
mm/page_alloc.c | 98 ++++++++++++++++++++++++++++++++------------------------
2 files changed, 67 insertions(+), 42 deletions(-)
Index: linux-2.6/mm/internal.h
===================================================================
--- linux-2.6.orig/mm/internal.h
+++ linux-2.6/mm/internal.h
@@ -47,4 +47,15 @@ static inline unsigned long page_order(s
VM_BUG_ON(!PageBuddy(page));
return page_private(page);
}
+
+#define ALLOC_HARDER 0x01 /* try to alloc harder */
+#define ALLOC_HIGH 0x02 /* __GFP_HIGH set */
+#define ALLOC_WMARK_MIN 0x04 /* use pages_min watermark */
+#define ALLOC_WMARK_LOW 0x08 /* use pages_low watermark */
+#define ALLOC_WMARK_HIGH 0x10 /* use pages_high watermark */
+#define ALLOC_NO_WATERMARKS 0x20 /* don't check watermarks at all */
+#define ALLOC_CPUSET 0x40 /* check for correct cpuset */
+
+int gfp_to_alloc_flags(gfp_t gfp_mask);
+
#endif
Index: linux-2.6/mm/page_alloc.c
===================================================================
--- linux-2.6.orig/mm/page_alloc.c
+++ linux-2.6/mm/page_alloc.c
@@ -1139,14 +1139,6 @@ failed:
return NULL;
}

-#define ALLOC_NO_WATERMARKS 0x01 /* don't check watermarks at all */
-#define ALLOC_WMARK_MIN 0x02 /* use pages_min watermark */
-#define ALLOC_WMARK_LOW 0x04 /* use pages_low watermark */
-#define ALLOC_WMARK_HIGH 0x08 /* use pages_high watermark */
-#define ALLOC_HARDER 0x10 /* try to alloc harder */
-#define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
-#define ALLOC_CPUSET 0x40 /* check for correct cpuset */
-
#ifdef CONFIG_FAIL_PAGE_ALLOC

static struct fail_page_alloc_attr {
@@ -1535,6 +1527,44 @@ static void set_page_owner(struct page *
#endif /* CONFIG_PAGE_OWNER */

/*
+ * get the deepest reaching allocation flags for the given gfp_mask
+ */
+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;
+
+ /*
+ * The caller may dip into page reserves a bit more if the caller
+ * cannot run direct reclaim, or if the caller has realtime scheduling
+ * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will
+ * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH).
+ */
+ if (gfp_mask & __GFP_HIGH)
+ alloc_flags |= ALLOC_HIGH;
+
+ if (!wait) {
+ alloc_flags |= ALLOC_HARDER;
+ /*
+ * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
+ * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
+ */
+ alloc_flags &= ~ALLOC_CPUSET;
+ } else if (unlikely(rt_task(p)) && !in_interrupt())
+ alloc_flags |= ALLOC_HARDER;
+
+ if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
+ if (!in_interrupt() &&
+ ((p->flags & PF_MEMALLOC) ||
+ unlikely(test_thread_flag(TIF_MEMDIE))))
+ alloc_flags |= ALLOC_NO_WATERMARKS;
+ }
+
+ return alloc_flags;
+}
+
+/*
* This is the 'heart' of the zoned buddy allocator.
*/
struct page * fastcall
@@ -1589,48 +1619,28 @@ restart:
* OK, we're below the kswapd watermark and have kicked background
* reclaim. Now things get more complex, so set up alloc_flags according
* to how we want to proceed.
- *
- * The caller may dip into page reserves a bit more if the caller
- * cannot run direct reclaim, or if the caller has realtime scheduling
- * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will
- * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH).
*/
- alloc_flags = ALLOC_WMARK_MIN;
- if ((unlikely(rt_task(p)) && !in_interrupt()) || !wait)
- alloc_flags |= ALLOC_HARDER;
- if (gfp_mask & __GFP_HIGH)
- alloc_flags |= ALLOC_HIGH;
- if (wait)
- alloc_flags |= ALLOC_CPUSET;
+ alloc_flags = gfp_to_alloc_flags(gfp_mask);

- /*
- * Go through the zonelist again. Let __GFP_HIGH and allocations
- * coming from realtime tasks go deeper into reserves.
- *
- * This is the last chance, in general, before the goto nopage.
- * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
- * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
- */
- page = get_page_from_freelist(gfp_mask, order, zonelist, alloc_flags);
+ /* This is the last chance, in general, before the goto nopage. */
+ page = get_page_from_freelist(gfp_mask, order, zonelist,
+ alloc_flags & ~ALLOC_NO_WATERMARKS);
if (page)
goto got_pg;

/* This allocation should allow future memory freeing. */
-
rebalance:
- if (((p->flags & PF_MEMALLOC) || unlikely(test_thread_flag(TIF_MEMDIE)))
- && !in_interrupt()) {
- if (!(gfp_mask & __GFP_NOMEMALLOC)) {
+ if (alloc_flags & ALLOC_NO_WATERMARKS) {
nofail_alloc:
- /* go through the zonelist yet again, ignoring mins */
- page = get_page_from_freelist(gfp_mask, order,
- zonelist, ALLOC_NO_WATERMARKS);
- if (page)
- goto got_pg;
- if (gfp_mask & __GFP_NOFAIL) {
- congestion_wait(WRITE, HZ/50);
- goto nofail_alloc;
- }
+ /* go through the zonelist yet again, ignoring mins */
+ page = get_page_from_freelist(gfp_mask, order, zonelist,
+ ALLOC_NO_WATERMARKS);
+ if (page)
+ goto got_pg;
+
+ if (wait && (gfp_mask & __GFP_NOFAIL)) {
+ congestion_wait(WRITE, HZ/50);
+ goto nofail_alloc;
}
goto nopage;
}
@@ -1639,6 +1649,10 @@ nofail_alloc:
if (!wait)
goto nopage;

+ /* Avoid recursion of direct reclaim */
+ if (p->flags & PF_MEMALLOC)
+ goto nopage;
+
cond_resched();

/* We now go into synchronous reclaim */
--

-
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