From bec013c40bc89671d8d457944fdf7d2b8e79d651 Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Thu, 12 Jan 2012 17:20:15 -0800 Subject: [PATCH] kdump: crashk_res init check for /sys/kernel/kexec_crash_size Currently it is possible to set the crash_size via the sysfs /sys/kernel/kexec_crash_size even if no crash kernel memory has been defined with the "crashkernel" parameter. In this case "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0. Unfortunately resource_size(&crashk_res) returns 1 in this case. This breaks the s390 implementation of crash_(un)map_reserved_pages(). To fix the problem the correct "old_size" is now calculated in crash_shrink_memory(). "old_size is set to "0" if crashk_res is not initialized. With this change crash_shrink_memory() will do nothing, when "crashk_res" is not initialized. It will return "0" for "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for "echo [not zero] > /sys/kernel/kexec_crash_size". In addition to that this patch also simplifies the "ret = -EINVAL" vs. "ret = 0" logic as suggested by Simon Horman. Signed-off-by: Michael Holzheu Reviewed-by: Dave Young Reviewed-by: WANG Cong Reviewed-by: Simon Horman Cc: Vivek Goyal Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/kexec.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/kernel/kexec.c b/kernel/kexec.c index 60bf181..7b088678 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1129,6 +1129,7 @@ int crash_shrink_memory(unsigned long new_size) { int ret = 0; unsigned long start, end; + unsigned long old_size; struct resource *ram_res; mutex_lock(&kexec_mutex); @@ -1139,11 +1140,9 @@ int crash_shrink_memory(unsigned long new_size) } start = crashk_res.start; end = crashk_res.end; - - if (new_size >= end - start + 1) { - ret = -EINVAL; - if (new_size == end - start + 1) - ret = 0; + old_size = (end == 0) ? 0 : end - start + 1; + if (new_size >= old_size) { + ret = (new_size == old_size) ? 0 : -EINVAL; goto unlock; } -- 2.7.4