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| author | Daniel De Graaf <dgdegra@tycho.nsa.gov> | 2010-08-10 18:02:45 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-11 08:59:12 -0700 |
| commit | c07fbfd17e614a76b194f371c5331e21e6cffb54 (patch) | |
| tree | 34bd53668b5b45b344411d49d8acf6d466004428 /drivers/video/fbmem.c | |
| parent | daf695fca877068d7533a1b431b09210e5ad0b6b (diff) | |
| download | lwn-c07fbfd17e614a76b194f371c5331e21e6cffb54.tar.gz lwn-c07fbfd17e614a76b194f371c5331e21e6cffb54.zip | |
fbmem: VM_IO set, but not propagated
When we setup up the VMA flags for the mmap flag and we end up using the
fallback mmap functionality we set the vma->vm_flags |= VM_IO. However we
neglect to propagate the flag to the vma->vm_page_prot.
This bug was found when Linux kernel was running under Xen. In that
scenario, any page that has VM_IO flag to it, means that it MUST be a
MMIO/VRAM backend memory , _not_ System RAM. That is what the fbmem.c
does: sets VM_IO, ioremaps the region - everything is peachy.
Well, not exactly. The vm_page_prot does not get the relevant PTE flags
set (_PAGE_IOMAP) which under Xen is a death-kneel to pages that are
referencing real physical devices but don't have that flag set.
This patch fixes this.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Tested-by: Eamon Walsh <ewalsh@tycho.nsa.gov>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/video/fbmem.c')
| -rw-r--r-- | drivers/video/fbmem.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index a8500c61bb16..b06647517c0e 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -1362,6 +1362,7 @@ fb_mmap(struct file *file, struct vm_area_struct * vma) vma->vm_pgoff = off >> PAGE_SHIFT; /* This is an IO map - tell maydump to skip this VMA */ vma->vm_flags |= VM_IO | VM_RESERVED; + vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); fb_pgprotect(file, vma, off); if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT, vma->vm_end - vma->vm_start, vma->vm_page_prot)) |