Messages in this thread | | | Date | Thu, 7 Feb 2019 14:36:24 +0100 | From | Oscar Salvador <> | Subject | Re: [PATCH] mm/memory-hotplug: Add sysfs hot-remove trigger |
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On Wed, Feb 06, 2019 at 05:03:53PM +0000, Robin Murphy wrote: > ARCH_MEMORY_PROBE is a useful thing for testing and debugging hotplug, > but being able to exercise the (arguably trickier) hot-remove path would > be even more useful. Extend the feature to allow removal of offline > sections to be triggered manually to aid development. > > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > --- > > This is inspired by a previous proposal[1], but in coming up with a > more robust interface I ended up rewriting the whole thing from > scratch. The lack of documentation is semi-deliberate, since I don't > like the idea of anyone actually relying on this interface as ABI, but > as a handy tool it felt useful enough to be worth sharing :)
Hi Robin,
I think this might come in handy, especially when trying to test hot-remove on arch's that do not have any means to hot-remove memory, or even on virtual platforms that do not have yet support for hot-remove depending on the platform, like qemu/arm64.
I could have used this while testing hot-remove on other archs for [1]
> > Robin. > > [1] https://lore.kernel.org/lkml/22d34fe30df0fbacbfceeb47e20cb1184af73585.1511433386.git.ar@linux.vnet.ibm.com/ >
> + if (mem->state != MEM_OFFLINE) > + return -EBUSY;
We do have the helper "is_memblock_offlined()", although it is only used in one place now. So, I would rather use it here as well.
> + > + ret = lock_device_hotplug_sysfs(); > + if (ret) > + return ret; > + > + if (device_remove_file_self(dev, attr)) { > + __remove_memory(pfn_to_nid(start_pfn), PFN_PHYS(start_pfn), > + MIN_MEMORY_BLOCK_SIZE * sections_per_block);
Sorry, I am not into sysfs inners, but I thought that: device_del::device_remove_attrs::device_remove_groups::sysfs_remove_groups would be enough to remove the dev attributes. I guess in this case that is not enough, could you explain why?
[1] https://patchwork.kernel.org/patch/10775339/ -- Oscar Salvador SUSE L3
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