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kexec: enable kexec_crash_size to support two crash kernel regions

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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: 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>
This commit is contained in:
Zhen Lei 2023-05-27 20:34:39 +08:00 committed by Andrew Morton
parent 5b7bfb32cb
commit 16c6006af4
1 changed files with 38 additions and 5 deletions
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43
kernel/kexec_core.c
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@ -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();