* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
-#include <linux/config.h>
#include <linux/module.h>
#include <linux/signal.h>
#include <linux/ptrace.h>
if (in_interrupt() || !mm)
goto no_context;
- down_read(&mm->mmap_sem);
+ /*
+ * As per x86, we may deadlock here. However, since the kernel only
+ * validly references user space from well defined areas of the code,
+ * we can bug out early if this is from code which shouldn't.
+ */
+ if (!down_read_trylock(&mm->mmap_sem)) {
+ if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
+ goto no_context;
+ down_read(&mm->mmap_sem);
+ }
+
fault = __do_page_fault(mm, addr, fsr, tsk);
up_read(&mm->mmap_sem);