Third time is the charm? Let's see ... :) This is the follow up of [1]: [PATCH v1 0/3] mm/memory_hotplug: Make virtio-mem play nicely with kexec-tools and [2]: [PATCH v2 0/3] mm/memory_hotplug: Allow to not create firmware memmap entries kexec (via kexec_load()) can currently not properly handle memory added via dax/kmem, and will have similar issues with virtio-mem. kexec-tools will currently add all memory to the fixed-up initial firmware memmap. In case of dax/kmem, this means that - in contrast to a proper reboot - how that persistent memory will be used can no longer be configured by the kexec'd kernel. In case of virtio-mem it will be harmful, because that memory might contain inaccessible pieces that require coordination with hypervisor first. In both cases, we want to let the driver in the kexec'd kernel handle detecting and adding the memory, like during an ordinary reboot. Introduce add_memory_driver_managed(). More on the samentics are in patch #1. In the future, we might want to make this behavior configurable for dax/kmem- either by configuring it in the kernel (which would then also allow to configure kexec_file_load()) or in kexec-tools by also adding "System RAM (kmem)" memory from /proc/iomem to the fixed-up initial firmware memmap. More on the motivation can be found in [1] and [2]. v2 -> v3: - Don't use flags for add_memory() and friends, provide add_memory_driver_managed() instead. - Flag memory resources via IORESOURCE_MEM_DRIVER_MANAGED and handle them in kexec. - Name memory resources "System RAM ($DRIVER)", visible via /proc/iomem - Added more details to the patch descriptions, especially regarding the history of /sys/firmware/memmap - Add a comment to the device-dax change. Dropped Dave's Ack as the v1 -> v2: - Don't change the resource name - Rename the flag to MHP_NO_FIRMWARE_MEMMAP to reflect what it is doing - Rephrase subjects/descriptions - Use the flag for dax/kmem [1] https://lkml.kernel.org/r/20200429160803.109056-1-david@xxxxxxxxxx [2] https://lkml.kernel.org/r/20200430102908.10107-1-david@xxxxxxxxxx David Hildenbrand (3): mm/memory_hotplug: Introduce add_memory_device_managed() kexec_file: Don't place kexec images on IORESOURCE_MEM_DRIVER_MANAGED device-dax: Add memory via add_memory_driver_managed() drivers/dax/kmem.c | 8 ++++- include/linux/ioport.h | 1 + include/linux/memory_hotplug.h | 2 ++ kernel/kexec_file.c | 5 +++ mm/memory_hotplug.c | 62 +++++++++++++++++++++++++++++++--- 5 files changed, 73 insertions(+), 5 deletions(-) -- 2.25.3 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
