Messages in this thread | | | Subject | Re: [PATCH] arm64: mm: account for hotplug memory when randomizing the linear region | From | David Hildenbrand <> | Date | Wed, 11 Nov 2020 10:11:03 +0100 |
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On 11.11.20 04:48, Anshuman Khandual wrote: > > > On 11/11/20 12:44 AM, Catalin Marinas wrote: >> On Wed, 14 Oct 2020 10:18:57 +0200, Ard Biesheuvel wrote: >>> As a hardening measure, we currently randomize the placement of >>> physical memory inside the linear region when KASLR is in effect. >>> Since the random offset at which to place the available physical >>> memory inside the linear region is chosen early at boot, it is >>> based on the memblock description of memory, which does not cover >>> hotplug memory. The consequence of this is that the randomization >>> offset may be chosen such that any hotplugged memory located above >>> memblock_end_of_DRAM() that appears later is pushed off the end of >>> the linear region, where it cannot be accessed. >>> >>> [...] >> >> Applied to arm64 (for-next/mem-hotplug), thanks! >> >> [1/1] arm64: mm: account for hotplug memory when randomizing the linear region >> https://git.kernel.org/arm64/c/97d6786e0669 >> > > Hello Catalin, > > Got delayed and never made here in time, sorry about that. Nonetheless, > I have got something working with respect to the generic mechanism that > David Hildenbrand had asked for earlier. > > https://patchwork.kernel.org/project/linux-arm-kernel/patch/1600332402-30123-1-git-send-email-anshuman.khandual@arm.com/ > > I am wondering if we could instead consider merging the above patch with > a small change that Ard had pointed out earlier [1], I will send out a > revision if required. > > I am asking this because the patch in question is a memory hotplug fix > and should be back ported to other stable releases. Implementing that > via the new proposed generic framework might make it difficult for a > possible arm64 specific backport. We could then add the new generic > framework and move this fix to an arch callback. Let me know if this > would be an feasible option. Thank you.
Sure, if it's a fix that is intended to be backported as well, then let's move forward with the simple fix and do a proper cleanup on top later. Thanks!
-- Thanks,
David / dhildenb
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