kexec: fix Oops in crash_shrink_memory()

When crashkernel is not enabled, "echo 0 > /sys/kernel/kexec_crash_size" OOPSes the kernel in crash_shrink_memory. This happens when crash_shrink_memory tries to release the 'crashk_res' resource which are not reserved. Also value of "/sys/kernel/kexec_crash_size" shows as 1, which should be 0. This patch fixes the OOPS in crash_shrink_memory and shows "/sys/kernel/kexec_crash_size" as 0 when crash kernel memory is not reserved. Signed-off-by: Pavan Naregundi <[email protected]> Reviewed-by: WANG Cong <[email protected]> Cc: Simon Horman <[email protected]> Cc: Vivek Goyal <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
goeke · Jun 29, 2010 · e05bd33 · e05bd33
1 parent 482ce51
commit e05bd33
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/kernel/kexec.c b/kernel/kexec.c
@@ -1089,9 +1089,10 @@ void crash_kexec(struct pt_regs *regs)
 
 size_t crash_get_memory_size(void)
 {
-	size_t size;
+	size_t size = 0;
 	mutex_lock(&kexec_mutex);
-	size = crashk_res.end - crashk_res.start + 1;
+	if (crashk_res.end != crashk_res.start)
+		size = crashk_res.end - crashk_res.start + 1;
 	mutex_unlock(&kexec_mutex);
 	return size;
 }
@@ -1134,7 +1135,7 @@ int crash_shrink_memory(unsigned long new_size)
 
 	free_reserved_phys_range(end, crashk_res.end);
 
-	if (start == end)
+	if ((start == end) && (crashk_res.parent != NULL))
 		release_resource(&crashk_res);
 	crashk_res.end = end - 1;