Commit 16c6006a authored by Zhen Lei's avatar Zhen Lei Committed by Andrew Morton
Browse files

kexec: enable kexec_crash_size to support two crash kernel regions 

The crashk_low_res should be considered by /sys/kernel/kexec_crash_size
to support two crash kernel regions shrinking if existing.

While doing it, crashk_low_res will only be shrunk when the entire
crashk_res is empty; and if the crashk_res is empty and crahk_low_res
is not, change crashk_low_res to be crashk_res.

[bhe@redhat.com: redo changelog]
Link: https://lkml.kernel.org/r/20230527123439.772-7-thunder.leizhen@huawei.com


Signed-off-by: default avatarZhen Lei <thunder.leizhen@huawei.com>
Acked-by: default avatarBaoquan 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5b7bfb32

kernel/kexec_core.c

+38 −5
Original line number Diff line number Diff line
@@ -1091,6 +1091,11 @@ __bpf_kfunc void crash_kexec(struct pt_regs *regs) 
	}

}



static inline resource_size_t crash_resource_size(const struct resource *res)

{

	return !res->end ? 0 : resource_size(res);

}



ssize_t crash_get_memory_size(void)

{

	ssize_t size = 0;
@@ -1098,8 +1103,8 @@ ssize_t crash_get_memory_size(void) 
	if (!kexec_trylock())

		return -EBUSY;



	if (crashk_res.end != crashk_res.start)

		size = resource_size(&crashk_res);

	size += crash_resource_size(&crashk_res);

	size += crash_resource_size(&crashk_low_res);



	kexec_unlock();

	return size;
@@ -1136,7 +1141,7 @@ static int __crash_shrink_memory(struct resource *old_res, 
int crash_shrink_memory(unsigned long new_size)

{

	int ret = 0;

	unsigned long old_size;

	unsigned long old_size, low_size;



	if (!kexec_trylock())

		return -EBUSY;
@@ -1145,14 +1150,42 @@ int crash_shrink_memory(unsigned long new_size) 
		ret = -ENOENT;

		goto unlock;

	}

	old_size = !crashk_res.end ? 0 : resource_size(&crashk_res);



	low_size = crash_resource_size(&crashk_low_res);

	old_size = crash_resource_size(&crashk_res) + low_size;

	new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN);

	if (new_size >= old_size) {

		ret = (new_size == old_size) ? 0 : -EINVAL;

		goto unlock;

	}



	ret = __crash_shrink_memory(&crashk_res, new_size);

	/*

	 * (low_size > new_size) implies that low_size is greater than zero.

	 * This also means that if low_size is zero, the else branch is taken.

	 *

	 * If low_size is greater than 0, (low_size > new_size) indicates that

	 * crashk_low_res also needs to be shrunken. Otherwise, only crashk_res

	 * needs to be shrunken.

	 */

	if (low_size > new_size) {

		ret = __crash_shrink_memory(&crashk_res, 0);

		if (ret)

			goto unlock;



		ret = __crash_shrink_memory(&crashk_low_res, new_size);

	} else {

		ret = __crash_shrink_memory(&crashk_res, new_size - low_size);

	}



	/* Swap crashk_res and crashk_low_res if needed */

	if (!crashk_res.end && crashk_low_res.end) {

		crashk_res.start = crashk_low_res.start;

		crashk_res.end   = crashk_low_res.end;

		release_resource(&crashk_low_res);

		crashk_low_res.start = 0;

		crashk_low_res.end   = 0;

		insert_resource(&iomem_resource, &crashk_res);

	}



unlock:

	kexec_unlock();