Messages in this thread | | | Subject | Re: [PATCH v3 04/11] arm64/mm: Add temporary arch_remove_memory() implementation | From | David Hildenbrand <> | Date | Tue, 4 Jun 2019 08:56:15 +0200 |
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On 03.06.19 23:41, Wei Yang wrote: > On Mon, May 27, 2019 at 01:11:45PM +0200, David Hildenbrand wrote: >> A proper arch_remove_memory() implementation is on its way, which also >> cleanly removes page tables in arch_add_memory() in case something goes >> wrong. > > Would this be better to understand? > > removes page tables created in arch_add_memory
That's not what this sentence expresses. Have a look at arch_add_memory(), in case __add_pages() fails, the page tables are not removed. This will also be fixed by Anshuman in the same shot.
> >> >> As we want to use arch_remove_memory() in case something goes wrong >> during memory hotplug after arch_add_memory() finished, let's add >> a temporary hack that is sufficient enough until we get a proper >> implementation that cleans up page table entries. >> >> We will remove CONFIG_MEMORY_HOTREMOVE around this code in follow up >> patches. >> >> Cc: Catalin Marinas <catalin.marinas@arm.com> >> Cc: Will Deacon <will.deacon@arm.com> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> Cc: Chintan Pandya <cpandya@codeaurora.org> >> Cc: Mike Rapoport <rppt@linux.ibm.com> >> Cc: Jun Yao <yaojun8558363@gmail.com> >> Cc: Yu Zhao <yuzhao@google.com> >> Cc: Robin Murphy <robin.murphy@arm.com> >> Cc: Anshuman Khandual <anshuman.khandual@arm.com> >> Signed-off-by: David Hildenbrand <david@redhat.com> >> --- >> arch/arm64/mm/mmu.c | 19 +++++++++++++++++++ >> 1 file changed, 19 insertions(+) >> >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index a1bfc4413982..e569a543c384 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -1084,4 +1084,23 @@ int arch_add_memory(int nid, u64 start, u64 size, >> return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, >> restrictions); >> } >> +#ifdef CONFIG_MEMORY_HOTREMOVE >> +void arch_remove_memory(int nid, u64 start, u64 size, >> + struct vmem_altmap *altmap) >> +{ >> + unsigned long start_pfn = start >> PAGE_SHIFT; >> + unsigned long nr_pages = size >> PAGE_SHIFT; >> + struct zone *zone; >> + >> + /* >> + * FIXME: Cleanup page tables (also in arch_add_memory() in case >> + * adding fails). Until then, this function should only be used >> + * during memory hotplug (adding memory), not for memory >> + * unplug. ARCH_ENABLE_MEMORY_HOTREMOVE must not be >> + * unlocked yet. >> + */ >> + zone = page_zone(pfn_to_page(start_pfn)); > > Compared with arch_remove_memory in x86. If altmap is not NULL, zone will be > retrieved from page related to altmap. Not sure why this is not the same?
This is a minimal implementation, sufficient for this use case here. A full implementation is in the works. For now, this function will not be used with an altmap (ZONE_DEVICE is not esupported for arm64 yet).
Thanks!
> >> + __remove_pages(zone, start_pfn, nr_pages, altmap); >> +} >> +#endif >> #endif >> -- >> 2.20.1 >
--
Thanks,
David / dhildenb
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