|author||Dave Hansen <email@example.com>||2013-03-07 08:31:51 -0800|
|committer||H. Peter Anvin <firstname.lastname@example.org>||2013-03-07 13:23:28 -0800|
x86: Do not try to sync identity map for non-mapped pages
kernel_map_sync_memtype() is called from a variety of contexts. The pat.c code that calls it seems to ensure that it is not called for non-ram areas by checking via pat_pagerange_is_ram(). It is important that it only be called on the actual identity map because there *IS* no map to sync for highmem pages, or for memory holes. The ioremap.c uses are not as careful as those from pat.c, and call kernel_map_sync_memtype() on PCI space which is in the middle of the kernel identity map _range_, but is not actually mapped. This patch adds a check to kernel_map_sync_memtype() which probably duplicates some of the checks already in pat.c. But, it is necessary for the ioremap.c uses and shouldn't hurt other callers. I have reproduced this bug and this patch fixes it for me and the original bug reporter: https://lkml.org/lkml/2013/2/5/396 Signed-off-by: Dave Hansen <email@example.com> Link: http://lkml.kernel.org/r/20130307163151.D9B58C4E@kernel.stglabs.ibm.com Signed-off-by: Dave Hansen <firstname.lastname@example.org> Tested-by: Tetsuo Handa <email@example.com> Signed-off-by: H. Peter Anvin <firstname.lastname@example.org>
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 2610bd93c896..657438858e83 100644
@@ -563,6 +563,13 @@ int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags)
if (base > __pa(high_memory-1))
+ * some areas in the middle of the kernel identity range
+ * are not mapped, like the PCI space.
+ if (!page_is_ram(base >> PAGE_SHIFT))
+ return 0;
id_sz = (__pa(high_memory-1) <= base + size) ?
__pa(high_memory) - base :