Merge tag 'dma-mapping-2022-12-23' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping fixes from Christoph Hellwig:
 "Fix up the sound code to not pass __GFP_COMP to the non-coherent DMA
  allocator, as it copes with that just as badly as the coherent
  allocator, and then add a check to make sure no one passes the flag
  ever again"

* tag 'dma-mapping-2022-12-23' of git://git.infradead.org/users/hch/dma-mapping:
  dma-mapping: reject GFP_COMP for noncoherent allocations
  ALSA: memalloc: don't use GFP_COMP for non-coherent dma allocations

Author: torvalds

kernel/dma/mapping.c

@@ -560,6 +560,8 @@ static struct page *__dma_alloc_pages(struct device *dev, size_t size,
 		return NULL;
 	if (WARN_ON_ONCE(gfp & (__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM)))
 		return NULL;
+	if (WARN_ON_ONCE(gfp & __GFP_COMP))
+		return NULL;
 
 	size = PAGE_ALIGN(size);
 	if (dma_alloc_direct(dev, ops))
@@ -645,6 +647,8 @@ struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size,
 
 	if (WARN_ON_ONCE(attrs & ~DMA_ATTR_ALLOC_SINGLE_PAGES))
 		return NULL;
+	if (WARN_ON_ONCE(gfp & __GFP_COMP))
+		return NULL;
 
 	if (ops && ops->alloc_noncontiguous)
 		sgt = ops->alloc_noncontiguous(dev, size, dir, gfp, attrs);

sound/core/memalloc.c

@@ -542,7 +542,7 @@ static void *snd_dma_noncontig_alloc(struct snd_dma_buffer *dmab, size_t size)
 	void *p;
 
 	sgt = dma_alloc_noncontiguous(dmab->dev.dev, size, dmab->dev.dir,
-				      DEFAULT_GFP | __GFP_COMP, 0);
+				      DEFAULT_GFP, 0);
 #ifdef CONFIG_SND_DMA_SGBUF
 	if (!sgt && !get_dma_ops(dmab->dev.dev)) {
 		if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG)
@@ -820,7 +820,7 @@ static void *snd_dma_noncoherent_alloc(struct snd_dma_buffer *dmab, size_t size)
 	void *p;
 
 	p = dma_alloc_noncoherent(dmab->dev.dev, size, &dmab->addr,
-				  dmab->dev.dir, DEFAULT_GFP | __GFP_COMP);
+				  dmab->dev.dir, DEFAULT_GFP);
 	if (p)
 		dmab->dev.need_sync = dma_need_sync(dmab->dev.dev, dmab->addr);
 	return p;