[PATCH] unpaged: fix sound Bad page states

Earlier I unifdefed PageCompound, so that snd_pcm_mmap_control_nopage and
others can give out a 0-order component of a higher-order page, which won't
be mistakenly freed when zap_pte_range unmaps it.  But many Bad page states
reported a PG_reserved was freed after all: I had missed that we need to
say __GFP_COMP to get compound page behaviour.

Some of these higher-order pages are allocated by snd_malloc_pages, some by
snd_malloc_dev_pages; or if SBUS, by sbus_alloc_consistent - but that has
no gfp arg, so add __GFP_COMP into its sparc32/64 implementations.

I'm still rather puzzled that DRM seems not to need a similar change.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/sparc/kernel/ioport.c

@@ -252,7 +252,7 @@ void *sbus_alloc_consistent(struct sbus_dev *sdev, long len, u32 *dma_addrp)
 	}
 
 	order = get_order(len_total);
-	if ((va = __get_free_pages(GFP_KERNEL, order)) == 0)
+	if ((va = __get_free_pages(GFP_KERNEL|__GFP_COMP, order)) == 0)
 		goto err_nopages;
 
 	if ((res = kmalloc(sizeof(struct resource), GFP_KERNEL)) == NULL)

arch/sparc64/kernel/sbus.c

@@ -327,7 +327,7 @@ void *sbus_alloc_consistent(struct sbus_dev *sdev, size_t size, dma_addr_t *dvma
 	order = get_order(size);
 	if (order >= 10)
 		return NULL;
-	first_page = __get_free_pages(GFP_KERNEL, order);
+	first_page = __get_free_pages(GFP_KERNEL|__GFP_COMP, order);
 	if (first_page == 0UL)
 		return NULL;
 	memset((char *)first_page, 0, PAGE_SIZE << order);

sound/core/memalloc.c

@@ -197,6 +197,7 @@ void *snd_malloc_pages(size_t size, gfp_t gfp_flags)
 
 	snd_assert(size > 0, return NULL);
 	snd_assert(gfp_flags != 0, return NULL);
+	gfp_flags |= __GFP_COMP;	/* compound page lets parts be mapped */
 	pg = get_order(size);
 	if ((res = (void *) __get_free_pages(gfp_flags, pg)) != NULL) {
 		mark_pages(virt_to_page(res), pg);
@@ -241,6 +242,7 @@ static void *snd_malloc_dev_pages(struct device *dev, size_t size, dma_addr_t *d
 	snd_assert(dma != NULL, return NULL);
 	pg = get_order(size);
 	gfp_flags = GFP_KERNEL
+		| __GFP_COMP	/* compound page lets parts be mapped */
 		| __GFP_NORETRY /* don't trigger OOM-killer */
 		| __GFP_NOWARN; /* no stack trace print - this call is non-critical */
 	res = dma_alloc_coherent(dev, PAGE_SIZE << pg, dma, gfp_flags);