x86, pci-dma.c: don't always add __GFP_NORETRY to gfp
Currently arch/x86/kernel/pci-dma.c always adds __GFP_NORETRY
to the allocation flags, because it wants to be reasonably
sure not to deadlock when calling alloc_pages().
But really that should only be done in two cases:
- when allocating memory in the lower 16 MB DMA zone.
If there's no free memory there, waiting or OOM killing is of no use
- when optimistically trying an allocation in the DMA32 zone
when dma_mask < DMA_32BIT_MASK hoping that the allocation
happens to fall within the limits of the dma_mask
Also blindly adding __GFP_NORETRY to the the gfp variable might
not be a good idea since we then also use it when calling
dma_ops->alloc_coherent(). Clearing it might also not be a
good idea, dma_alloc_coherent()'s caller might have set it
on purpose. The gfp variable should not be clobbered.
[ mingo@elte.hu: converted to delta patch ontop of previous version. ]
Signed-off-by: Miquel van Smoorenburg <miquels@cistron.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 069e843..dc00a13 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -378,6 +378,7 @@
struct page *page;
unsigned long dma_mask = 0;
dma_addr_t bus;
+ int noretry = 0;
/* ignore region specifiers */
gfp &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
@@ -397,19 +398,25 @@
if (dev->dma_mask == NULL)
return NULL;
+ /* Don't invoke OOM killer or retry in lower 16MB DMA zone */
+ if (gfp & __GFP_DMA)
+ noretry = 1;
+
#ifdef CONFIG_X86_64
/* Why <=? Even when the mask is smaller than 4GB it is often
larger than 16MB and in this case we have a chance of
finding fitting memory in the next higher zone first. If
not retry with true GFP_DMA. -AK */
- if (dma_mask <= DMA_32BIT_MASK && !(gfp & GFP_DMA))
+ if (dma_mask <= DMA_32BIT_MASK && !(gfp & GFP_DMA)) {
gfp |= GFP_DMA32;
+ if (dma_mask < DMA_32BIT_MASK)
+ noretry = 1;
+ }
#endif
again:
- /* Don't invoke OOM killer or retry in lower 16MB DMA zone */
page = dma_alloc_pages(dev,
- (gfp & GFP_DMA) ? gfp | __GFP_NORETRY : gfp, get_order(size));
+ noretry ? gfp | __GFP_NORETRY : gfp, get_order(size));
if (page == NULL)
return NULL;