diff options
| author | Zhen Lei <thunder.leizhen@huawei.com> | 2023-05-27 20:34:34 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-06-09 17:44:23 -0700 |
| commit | 1cba6c4309f03de570202c46f03df3f73a0d4c82 (patch) | |
| tree | 9762f1f38abce8ba9b94a98aeb38c638f3695c47 /kernel/kexec_core.c | |
| parent | 69fe5c430ccd09a4c6e2d0b13d1164812983e2a1 (diff) | |
kexec: fix a memory leak in crash_shrink_memory()
Patch series "kexec: enable kexec_crash_size to support two crash kernel
regions".
When crashkernel=X fails to reserve region under 4G, it will fall back to
reserve region above 4G and a region of the default size will also be
reserved under 4G. Unfortunately, /sys/kernel/kexec_crash_size only
supports one crash kernel region now, the user cannot sense the low memory
reserved by reading /sys/kernel/kexec_crash_size. Also, low memory cannot
be freed by writing this file.
For example:
resource_size(crashk_res) = 512M
resource_size(crashk_low_res) = 256M
The result of 'cat /sys/kernel/kexec_crash_size' is 512M, but it should be
768M. When we execute 'echo 0 > /sys/kernel/kexec_crash_size', the size
of crashk_res becomes 0 and resource_size(crashk_low_res) is still 256 MB,
which is incorrect.
Since crashk_res manages the memory with high address and crashk_low_res
manages the memory with low address, crashk_low_res is shrunken only when
all crashk_res is shrunken. And because when there is only one crash
kernel region, crashk_res is always used. Therefore, if all crashk_res is
shrunken and crashk_low_res still exists, swap them.
This patch (of 6):
If the value of parameter 'new_size' is in the semi-open and semi-closed
interval (crashk_res.end - KEXEC_CRASH_MEM_ALIGN + 1, crashk_res.end], the
calculation result of ram_res is:
ram_res->start = crashk_res.end + 1
ram_res->end = crashk_res.end
The operation of insert_resource() fails, and ram_res is not added to
iomem_resource. As a result, the memory of the control block ram_res is
leaked.
In fact, on all architectures, the start address and size of crashk_res
are already aligned by KEXEC_CRASH_MEM_ALIGN. Therefore, we do not need
to round up crashk_res.start again. Instead, we should round up
'new_size' in advance.
Link: https://lkml.kernel.org/r/20230527123439.772-1-thunder.leizhen@huawei.com
Link: https://lkml.kernel.org/r/20230527123439.772-2-thunder.leizhen@huawei.com
Fixes: 6480e5a09237 ("kdump: add missing RAM resource in crash_shrink_memory()")
Fixes: 06a7f711246b ("kexec: premit reduction of the reserved memory size")
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>
Diffstat (limited to 'kernel/kexec_core.c')
| -rw-r--r-- | kernel/kexec_core.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 3d578c6fefee..22acee18195a 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -1122,6 +1122,7 @@ int crash_shrink_memory(unsigned long new_size) start = crashk_res.start; end = crashk_res.end; old_size = (end == 0) ? 0 : end - start + 1; + new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN); if (new_size >= old_size) { ret = (new_size == old_size) ? 0 : -EINVAL; goto unlock; @@ -1133,9 +1134,7 @@ int crash_shrink_memory(unsigned long new_size) goto unlock; } - start = roundup(start, KEXEC_CRASH_MEM_ALIGN); - end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN); - + end = start + new_size; crash_free_reserved_phys_range(end, crashk_res.end); if ((start == end) && (crashk_res.parent != NULL)) |