[PATCH 03/11] unpaged: sound nopage get_page

[Hugh Dickins]

Something noticed when studying use of VM_RESERVED in different drivers:
snd_usX2Y_hwdep_pcm_vm_nopage omitted to get_page: fixed.

And how did this work before?  Aargh!  That nopage is returning a page
from within a buffer allocated by snd_malloc_pages, which allocates a
high-order page, then does SetPageReserved on each 0-order page within.

That would have worked in 2.6.14, because when the area was unmapped,
PageReserved inhibited put_page.  2.6.15-rc1 removed that inhibition
(while leaving ineffective PageReserveds around for now), but it hasn't
caused trouble because.. we've not been freeing from VM_RESERVED at all.

Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx>
---

 sound/usb/usx2y/usx2yhwdeppcm.c |    1 +
 1 files changed, 1 insertion(+)

--- unpaged02/sound/usb/usx2y/usx2yhwdeppcm.c	2005-11-12 09:01:30.000000000 +0000
+++ unpaged03/sound/usb/usx2y/usx2yhwdeppcm.c	2005-11-17 15:10:34.000000000 +0000
@@ -691,6 +691,7 @@ static struct page * snd_usX2Y_hwdep_pcm
 	snd_assert((offset % PAGE_SIZE) == 0, return NOPAGE_OOM);
 	vaddr = (char*)((usX2Ydev_t*)area->vm_private_data)->hwdep_pcm_shm + offset;
 	page = virt_to_page(vaddr);
+	get_page(page);
 
 	if (type)
 		*type = VM_FAULT_MINOR;
-
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