kexec: clear crashk_res if all its memory has been released

If the resource of crashk_res has been released, it is better to clear
crashk_res.start and crashk_res.end.  Because 'end = start - 1' is not
reasonable, and in some places the test is based on crashk_res.end, not
resource_size(&crashk_res).

Link: https://lkml.kernel.org/r/20230527123439.772-4-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Cong Wang <amwang@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index d1ab139dd490..bcc86a250ab3 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1137,15 +1137,18 @@ int crash_shrink_memory(unsigned long new_size)
 	end = start + new_size;
 	crash_free_reserved_phys_range(end, crashk_res.end);
 
-	if (start == end)
-		release_resource(&crashk_res);
-
 	ram_res->start = end;
 	ram_res->end = crashk_res.end;
 	ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;
 	ram_res->name = "System RAM";
 
-	crashk_res.end = end - 1;
+	if (start == end) {
+		release_resource(&crashk_res);
+		crashk_res.start = 0;
+		crashk_res.end = 0;
+	} else {
+		crashk_res.end = end - 1;
+	}
 
 	insert_resource(&iomem_resource, ram_res);