From e05bd3367bd3d88715b53766f95bb3a8ec7ab59e Mon Sep 17 00:00:00 2001
From: Pavan Naregundi <pavan@linux.vnet.ibm.com>
Date: Tue, 29 Jun 2010 15:05:28 -0700
Subject: [PATCH] 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 <pavan@linux.vnet.ibm.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Simon Horman <horms@verge.net.au>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/kexec.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 474a84715eaca..131b1703936f6 100644
--- 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;
--
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