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Introduce a function to get reserved memory size 

The size of the reserved memory in the functions show_reserved_mem,
check_crash_mem_reserved, and do_estimate are fetched from the sysfs
node `/sys/kernel/kexec_crash_size`. However, in the case of fadump,
the reserved area size is instead present in
/sys/kernel/fadump/mem_reserved.

For example:

$ kdumpctl showmem
kdump: Dump mode is fadump
kdump: Reserved 0MB memory for crash kernel

The above command showed 0MB for Reserved memory which is incorrect, the
actual reservation was 2048MB.

To resolve this issue a new helper function is introduced to fetch
reserved memory size based on the dump mode. For "fadump" mode,
it looks in `/sys/kernel/fadump/mem_reserved`, otherwise, it uses
`/sys/kernel/kexec_crash_size`. And all functions that previously
fetching reserved memory directly from `/sys/kernel/kexec_crash_size`
sysfs node are now updated to use this new function to get the reserved
memory size.

With the fix in place, the `kdumpctl showmem` command will now display
correct reserved memory size.

$ kdumpctl showmem
kdump: Dump mode is fadump
kdump: Reserved 2048MB memory for crash kernel

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Reported-by: Sachin P Bappalige <sachinpb@linux.vnet.ibm.com>
Reviewed-by: Coiby Xu <coxu@redhat.com>
This commit is contained in:
Sourabh Jain 2023-08-02 20:36:48 +05:30 committed by Coiby Xu
parent b725cdb45e
commit 4b7b7736ee
2 changed files with 16 additions and 3 deletions
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15
kdump-lib.sh
View File

@ -344,11 +344,24 @@ is_mount_in_dracut_args()
[[ " $(kdump_get_conf_val dracut_args)" =~ .*[[:space:]]--mount[=[:space:]].* ]]
}
get_reserved_mem_size()
{
local reserved_mem_size=0
if is_fadump_capable; then
reserved_mem_size=$(< /sys/kernel/fadump/mem_reserved)
else
reserved_mem_size=$(< /sys/kernel/kexec_crash_size)
fi
echo "$reserved_mem_size"
}
check_crash_mem_reserved()
{
local mem_reserved
mem_reserved=$(< /sys/kernel/kexec_crash_size)
mem_reserved=$(get_reserved_mem_size)
if [[ $mem_reserved -eq 0 ]]; then
derror "No memory reserved for crash kernel"
return 1

4
kdumpctl
View File

@ -856,7 +856,7 @@ show_reserved_mem()
local mem
local mem_mb
mem=$(< /sys/kernel/kexec_crash_size)
mem=$(get_reserved_mem_size)
mem_mb=$((mem / 1024 / 1024))
dinfo "Reserved ${mem_mb}MB memory for crash kernel"
@ -1270,7 +1270,7 @@ do_estimate()
# The default pre-reserved crashkernel value
baseline_size=$((baseline * size_mb))
# Current reserved crashkernel size
reserved_size=$(< /sys/kernel/kexec_crash_size)
reserved_size=$(get_reserved_mem_size)
# A pre-estimated value for userspace usage and kernel
# runtime allocation, 64M should good for most cases
runtime_size=$((64 * size_mb))