kdump: add missing RAM resource in crash_shrink_memory()
When shrinking crashkernel memory using /sys/kernel/kexec_crash_size for
the newly added memory no RAM resource is created at the moment.
Example:
$ cat /proc/iomem
00000000-bfffffff : System RAM
00000000-005b7ac3 : Kernel code
005b7ac4-009743bf : Kernel data
009bb000-00a85c33 : Kernel bss
c0000000-cfffffff : Crash kernel
d0000000-ffffffff : System RAM
$ echo 0 > /sys/kernel/kexec_crash_size
$ cat /proc/iomem
00000000-bfffffff : System RAM
00000000-005b7ac3 : Kernel code
005b7ac4-009743bf : Kernel data
009bb000-00a85c33 : Kernel bss
<<-- here is System RAM missing
d0000000-ffffffff : System RAM
One result of this bug is that the memory chunk can never be set offline
using memory hotplug. With this patch I insert a new "System RAM"
resource for the released memory. Then the upper example looks like the
following:
$ echo 0 > /sys/kernel/kexec_crash_size
$ cat /proc/iomem
00000000-bfffffff : System RAM
00000000-005b7ac3 : Kernel code
005b7ac4-009743bf : Kernel data
009bb000-00a85c33 : Kernel bss
c0000000-cfffffff : System RAM <<-- new rescoure
d0000000-ffffffff : System RAM
And now I can set chunk c0000000-cfffffff offline.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 20ed47a..60bf181 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1129,6 +1129,7 @@
{
int ret = 0;
unsigned long start, end;
+ struct resource *ram_res;
mutex_lock(&kexec_mutex);
@@ -1146,6 +1147,12 @@
goto unlock;
}
+ ram_res = kzalloc(sizeof(*ram_res), GFP_KERNEL);
+ if (!ram_res) {
+ ret = -ENOMEM;
+ goto unlock;
+ }
+
start = roundup(start, KEXEC_CRASH_MEM_ALIGN);
end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN);
@@ -1154,7 +1161,15 @@
if ((start == end) && (crashk_res.parent != NULL))
release_resource(&crashk_res);
+
+ ram_res->start = end;
+ ram_res->end = crashk_res.end;
+ ram_res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
+ ram_res->name = "System RAM";
+
crashk_res.end = end - 1;
+
+ insert_resource(&iomem_resource, ram_res);
crash_unmap_reserved_pages();
unlock: