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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>
This commit is contained in:
Miquel van Smoorenburg 2008-06-05 18:14:44 +02:00 committed by Ingo Molnar
parent f529626a86
commit b7f09ae583
1 changed files with 10 additions and 3 deletions
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13
arch/x86/kernel/pci-dma.c
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@ -378,6 +378,7 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
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 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
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;