path: root/mm/mmap.c
diff options
authorMagnus Damm <damm@opensource.se>2009-12-14 17:59:49 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-15 08:53:21 -0800
commitc9d0bf241451a3ab7d02e1652c22b80cd7d93e8f (patch)
treef72d7eedf3fee82193407c7190321399833f422c /mm/mmap.c
parent62c0c2f198c1f2ead05c961e83ef486c45888325 (diff)
mm: uncached vma support with writenotify
Modify the generic mmap() code to keep the cache attribute in vma->vm_page_prot regardless if writenotify is enabled or not. Without this patch the cache configuration selected by f_op->mmap() is overwritten if writenotify is enabled, making it impossible to keep the vma uncached. Needed by drivers such as drivers/video/sh_mobile_lcdcfb.c which uses deferred io together with uncached memory. Signed-off-by: Magnus Damm <damm@opensource.se> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Jaya Kumar <jayakumar.lkml@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
1 files changed, 13 insertions, 1 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 02c09f33df8..d9c77b2dbe9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1198,8 +1198,20 @@ munmap_back:
goto free_vma;
- if (vma_wants_writenotify(vma))
+ if (vma_wants_writenotify(vma)) {
+ pgprot_t pprot = vma->vm_page_prot;
+ /* Can vma->vm_page_prot have changed??
+ *
+ * Answer: Yes, drivers may have changed it in their
+ * f_op->mmap method.
+ *
+ * Ensures that vmas marked as uncached stay that way.
+ */
vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
+ if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+ }
vma_link(mm, vma, prev, rb_link, rb_parent);
file = vma->vm_file;