[PATCH] unpaged: sound nopage get_page

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@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/sound/usb/usx2y/usx2yhwdeppcm.c b/sound/usb/usx2y/usx2yhwdeppcm.c
index 0dc828ff9e94dea68e8aea8fed84370d37dbd6f8..c9136a98755fa0c396fb6b4e4ea79ae97a749147 100644 (file)
--- a/sound/usb/usx2y/usx2yhwdeppcm.c
+++ b/sound/usb/usx2y/usx2yhwdeppcm.c
@@ -691,6 +691,7 @@ static struct page * snd_usX2Y_hwdep_pcm_vm_nopage(struct vm_area_struct *area,
        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;