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kexec: fix Oops in crash_shrink_memory()

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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>
This commit is contained in:
Pavan Naregundi 2010-06-29 15:05:28 -07:00 • committed by Linus Torvalds
parent 482ce512c5
commit e05bd3367b
1 changed files with 4 additions and 3 deletions
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7
kernel/kexec.c
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@ -1089,9 +1089,10 @@ void crash_kexec(struct pt_regs *regs)
size_t crash_get_memory_size(void) size_t crash_get_memory_size(void)
{ {
size_t size; size_t size = 0;
mutex_lock(&kexec_mutex); 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); mutex_unlock(&kexec_mutex);
return size; return size;
} }
@ -1134,7 +1135,7 @@ int crash_shrink_memory(unsigned long new_size)
free_reserved_phys_range(end, crashk_res.end); free_reserved_phys_range(end, crashk_res.end);
if (start == end) if ((start == end) && (crashk_res.parent != NULL))
release_resource(&crashk_res); release_resource(&crashk_res);
crashk_res.end = end - 1; crashk_res.end = end - 1;