Commit 60f583d5 authored by Dave Hansen's avatar Dave Hansen Committed by H. Peter Anvin
Browse files

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:

Signed-off-by: default avatarDave Hansen <>

Signed-off-by: default avatarDave Hansen <>
Tested-by: default avatarTetsuo Handa <>
Signed-off-by: default avatarH. Peter Anvin <>
parent 3c4aff6b
......@@ -563,6 +563,13 @@ int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags)
if (base > __pa(high_memory-1))
return 0;
* 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 :
Supports Markdown
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment