The patch titled
Subject: kdump: crashk_res init check for /sys/kernel/kexec_crash_size
has been added to the -mm tree. Its filename is
kdump-crashk_res-init-check-for-sys-kernel-kexec_crash_size.patch
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------------------------------------------------------
From: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx>
Subject: kdump: crashk_res init check for /sys/kernel/kexec_crash_size
Currently it is possible to set the crash_size via the sysfs
/sys/kernel/kexec_crash_size even if no crash kernel memory has been
defined with the "crashkernel" parameter. In this case "crashk_res" is
not initialized and crashk_res.start = crashk_res.end = 0. Unfortunately
resource_size(&crashk_res) returns 1 in this case. This breaks the s390
implementation of crash_(un)map_reserved_pages().
To fix the problem the correct "old_size" is now calculated in
crash_shrink_memory(). "old_size is set to "0" if crashk_res is not
initialized. With this change crash_shrink_memory() will do nothing, when
"crashk_res" is not initialized. It will return "0" for "echo 0 >
/sys/kernel/kexec_crash_size" and -EINVAL for "echo [not zero] >
/sys/kernel/kexec_crash_size".
In addition to that this patch also simplifies the "ret = -EINVAL" vs.
"ret = 0" logic as suggested by Simon Horman.
Signed-off-by: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Dave Young <dyoung@xxxxxxxxxx>
Reviewed-by: WANG Cong <xiyou.wangcong@xxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kexec.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff -puN kernel/kexec.c~kdump-crashk_res-init-check-for-sys-kernel-kexec_crash_size kernel/kexec.c
--- a/kernel/kexec.c~kdump-crashk_res-init-check-for-sys-kernel-kexec_crash_size
+++ a/kernel/kexec.c
@@ -1129,6 +1129,7 @@ int crash_shrink_memory(unsigned long ne
{
int ret = 0;
unsigned long start, end;
+ unsigned long old_size;
struct resource *ram_res;
mutex_lock(&kexec_mutex);
@@ -1139,11 +1140,9 @@ int crash_shrink_memory(unsigned long ne
}
start = crashk_res.start;
end = crashk_res.end;
-
- if (new_size >= end - start + 1) {
- ret = -EINVAL;
- if (new_size == end - start + 1)
- ret = 0;
+ old_size = (end == 0) ? 0 : end - start + 1;
+ if (new_size >= old_size) {
+ ret = (new_size == old_size) ? 0 : -EINVAL;
goto unlock;
}
_
Subject: Subject: kdump: crashk_res init check for /sys/kernel/kexec_crash_size
Patches currently in -mm which might be from holzheu@xxxxxxxxxxxxxxxxxx are
linux-next.patch
kdump-add-missing-ram-resource-in-crash_shrink_memory.patch
kdump-add-udev-events-for-memory-online-offline.patch
kdump-crashk_res-init-check-for-sys-kernel-kexec_crash_size.patch
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