mm: do not export ioremap_page_range symbol for external module

Recently, I've found cases in which ioremap_page_range was used
incorrectly, in external modules, leading to crashes.  This can be
partly attributed to the fact that ioremap_page_range is lower-level,
with fewer protections, as compared to the other functions that an
external module would typically call.  Those include:

     ioremap_cache
     ioremap_nocache
     ioremap_prot
     ioremap_uc
     ioremap_wc
     ioremap_wt

...each of which wraps __ioremap_caller, which in turn provides a safer
way to achieve the mapping.

Therefore, stop EXPORT-ing ioremap_page_range.

Link: http://lkml.kernel.org/r/1485173220-29010-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Suggested-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/ioremap.c b/lib/ioremap.c
index 86c8911b0e3a6fff02b9e52faa11816cfe508362..a3e14ce92a5684a662c2c8f80f97e6fef95943b7 100644 (file)
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -144,4 +144,3 @@ int ioremap_page_range(unsigned long addr,
 
        return err;
 }
-EXPORT_SYMBOL_GPL(ioremap_page_range);