diff options
| author | Magnus Damm <damm@opensource.se> | 2009-12-14 17:59:49 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-15 08:53:21 -0800 |
| commit | c9d0bf241451a3ab7d02e1652c22b80cd7d93e8f (patch) | |
| tree | f72d7eedf3fee82193407c7190321399833f422c | |
| parent | 62c0c2f198c1f2ead05c961e83ef486c45888325 (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>
| -rw-r--r-- | mm/mmap.c | 14 |
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; |