kexec: check if crashk_res_low exists when exclude it from crash mem ranges

Add a check if crashk_res_low exists just like GART region does.  If
crashk_res_low doesn't exist, calling exclude_mem_range is unnecessary.

Meanwhile, since crashk_res_low has been initialized at definition, it's
safe just use "if (crashk_low_res.end)" to check if it's exist.  And this
can make it consistent with other places of check.

Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index a618fcd2c07d..f5ab56d14287 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -237,7 +237,7 @@ static void fill_up_crash_elf_data(struct crash_elf_data *ced,
         ced->max_nr_ranges++;
 
         /* If crashk_low_res is not 0, another range split possible */
-        if (crashk_low_res.end != 0)
+        if (crashk_low_res.end)
                 ced->max_nr_ranges++;
 }
 
@@ -335,9 +335,11 @@ static int elf_header_exclude_ranges(struct crash_elf_data *ced,
         if (ret)
                 return ret;
 
-        ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
-        if (ret)
-                return ret;
+        if (crashk_low_res.end) {
+                ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
+                if (ret)
+                        return ret;
+        }
 
         /* Exclude GART region */
         if (ced->gart_end) {