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sysconfig: disable kfence in kdump kernel

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Resolves: https://issues.redhat.com/browse/RHEL-103429
Upstream: rhkdump/kdump-utils
Conflict: Need manually edit kdump.sysconfig files

commit ddb0bab1f7e1e43a802993aadad03f85a3c045a9
Author: Baoquan He <bhe@redhat.com>
Date:   Wed Jun 25 23:30:24 2025 +0800

    sysconfig: disable kfence in kdump kernel

    In the current fedora and RHEL, below config items related to kfence
    feature are set by default:

    ===
    CONFIG_HAVE_ARCH_KFENCE=y
    CONFIG_KFENCE=y
    CONFIG_KFENCE_SAMPLE_INTERVAL=100
    CONFIG_KFENCE_NUM_OBJECTS=255
    CONFIG_KFENCE_STRESS_TEST_FAULTS=0
    CONFIG_KFENCE_KUNIT_TEST=m
    ===

    With them set, on x86_64, it will cost 2M extra memory used for kfence when
    page size if 4K; while on arm64 with 64K page size, it will cost 32M extra
    memory. This doesn't take memory cost of initializing and running kfence
    itself into account, here only saying the kfence objects and guarded
    pages. However, it doesn't make any sense to have kfence in a kdump
    kernel. Hence, disable kfence in kdump kernel to save crashkernel
    memory.

Signed-off-by: Baoquan He <bhe@redhat.com>
This commit is contained in:
Baoquan He 2025-08-06 15:23:56 +08:00
parent dbc841969b
commit 6563c70944
7 changed files with 8 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
kdump.sysconfig
View File

@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet log_buf_len swio
# This variable lets us append arguments to the current kdump commandline
# after processed by KDUMP_COMMANDLINE_REMOVE
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices novmcoredd cma=0 hugetlb_cma=0"
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices novmcoredd cma=0 hugetlb_cma=0 kfence.sample_interval=0"
# Any additional kexec arguments required. In most situations, this should
# be left empty

2
kdump.sysconfig.aarch64
View File

@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet log_buf_len swio
# This variable lets us append arguments to the current kdump commandline
# after processed by KDUMP_COMMANDLINE_REMOVE
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory udev.children-max=2 panic=10 swiotlb=noforce novmcoredd cma=0 hugetlb_cma=0"
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory udev.children-max=2 panic=10 swiotlb=noforce novmcoredd cma=0 hugetlb_cma=0 kfence.sample_interval=0"
# Any additional kexec arguments required. In most situations, this should
# be left empty

2
kdump.sysconfig.i386
View File

@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet log_buf_len swio
# This variable lets us append arguments to the current kdump commandline
# after processed by KDUMP_COMMANDLINE_REMOVE
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off udev.children-max=2 panic=10 transparent_hugepage=never novmcoredd cma=0 hugetlb_cma=0"
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off udev.children-max=2 panic=10 transparent_hugepage=never novmcoredd cma=0 hugetlb_cma=0 kfence.sample_interval=0"
# Any additional kexec arguments required. In most situations, this should
# be left empty

2
kdump.sysconfig.ppc64
View File

@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet log_buf_len swio
# This variable lets us append arguments to the current kdump commandline
# after processed by KDUMP_COMMANDLINE_REMOVE
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never novmcoredd hugetlb_cma=0"
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never novmcoredd hugetlb_cma=0 kfence.sample_interval=0"
# Any additional kexec arguments required. In most situations, this should
# be left empty

4
kdump.sysconfig.ppc64le
View File

@ -21,11 +21,11 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet log_buf_len swio
# This variable lets us append arguments to the current kdump commandline
# after processed by KDUMP_COMMANDLINE_REMOVE
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never novmcoredd hugetlb_cma=0"
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never novmcoredd hugetlb_cma=0 kfence.sample_interval=0"
# This variable lets us append arguments to fadump (powerpc) capture kernel,
# further to the parameters passed via the bootloader.
FADUMP_COMMANDLINE_APPEND="nr_cpus=16 numa=off cgroup_disable=memory cma=0 kvm_cma_resv_ratio=0 hugetlb_cma=0 transparent_hugepage=never novmcoredd udev.children-max=2"
FADUMP_COMMANDLINE_APPEND="nr_cpus=16 numa=off cgroup_disable=memory cma=0 kvm_cma_resv_ratio=0 hugetlb_cma=0 transparent_hugepage=never novmcoredd udev.children-max=2 kfence.sample_interval=0"
# Any additional kexec arguments required. In most situations, this should
# be left empty

2
kdump.sysconfig.s390x
View File

@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet log_buf_len swio
# This variable lets us append arguments to the current kdump commandline
# after processed by KDUMP_COMMANDLINE_REMOVE
KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off udev.children-max=2 panic=10 transparent_hugepage=never novmcoredd vmcp_cma=0 cma=0 hugetlb_cma=0"
KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off udev.children-max=2 panic=10 transparent_hugepage=never novmcoredd vmcp_cma=0 cma=0 hugetlb_cma=0 kfence.sample_interval=0"
# Any additional /sbin/mkdumprd arguments required.
MKDUMPRD_ARGS=""

2
kdump.sysconfig.x86_64
View File

@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet log_buf_len swio
# This variable lets us append arguments to the current kdump commandline
# after processed by KDUMP_COMMANDLINE_REMOVE
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory mce=off numa=off udev.children-max=2 panic=10 acpi_no_memhotplug transparent_hugepage=never nokaslr hest_disable novmcoredd cma=0 hugetlb_cma=0 pcie_ports=compat"
KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory mce=off numa=off udev.children-max=2 panic=10 acpi_no_memhotplug transparent_hugepage=never nokaslr hest_disable novmcoredd cma=0 hugetlb_cma=0 pcie_ports=compat kfence.sample_interval=0"
# Any additional kexec arguments required. In most situations, this should
# be left empty