Messages in this thread | | | Subject | Re: [PATCH 2/2] arm64: allow hotpluggable sections to be offlined | From | Anshuman Khandual <> | Date | Mon, 19 Oct 2020 12:26:36 +0530 |
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On 10/17/2020 01:04 PM, David Hildenbrand wrote: > >> Am 17.10.2020 um 04:03 schrieb Sudarshan Rajagopalan <sudaraja@codeaurora.org>: >> >> On receiving the MEM_GOING_OFFLINE notification, we disallow offlining of >> any boot memory by checking if section_early or not. With the introduction >> of SECTION_MARK_HOTPLUGGABLE, allow boot mem sections that are marked as >> hotpluggable with this bit set to be offlined and removed. This now allows >> certain boot mem sections to be offlined. >> > > The check (notifier) is in arm64 code. I don‘t see why you cannot make such decisions completely in arm64 code? Why would you have to mark sections? > > Also, I think I am missing from *where* the code that marks sections removable is even called? Who makes such decisions?
From the previous patch.
+EXPORT_SYMBOL_GPL(mark_memory_hotpluggable);
> > This feels wrong. > >> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org> >> Cc: Catalin Marinas <catalin.marinas@arm.com> >> Cc: Will Deacon <will@kernel.org> >> Cc: Anshuman Khandual <anshuman.khandual@arm.com> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: Gavin Shan <gshan@redhat.com> >> Cc: Logan Gunthorpe <logang@deltatee.com> >> Cc: David Hildenbrand <david@redhat.com> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: Steven Price <steven.price@arm.com> >> Cc: Suren Baghdasaryan <surenb@google.com> >> --- >> arch/arm64/mm/mmu.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 75df62fea1b6..fb8878698672 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -1487,7 +1487,7 @@ static int prevent_bootmem_remove_notifier(struct notifier_block *nb, >> >> for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) { >> ms = __pfn_to_section(pfn); >> - if (early_section(ms)) >> + if (early_section(ms) && !removable_section(ms))
Till challenges related to boot memory removal on arm64 platform get resolved, no portion of boot memory can be offlined. Let alone via a driver making such decisions.
>> return NOTIFY_BAD; >> } >> return NOTIFY_OK; >> -- >> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, >> a Linux Foundation Collaborative Project >> > >
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