Messages in this thread | | | Subject | Re: [PATCH] arm64: mm: account for hotplug memory when randomizing the linear region | From | Anshuman Khandual <> | Date | Fri, 13 Nov 2020 08:46:27 +0530 |
| |
On 11/12/20 2:55 PM, Catalin Marinas wrote: > Hi Anshuman, > > On Wed, Nov 11, 2020 at 09:18:56AM +0530, 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 >> >> 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/ > > There was a lot of discussion around this patch but I haven't seen any > new version posted.
Just posted before some time.
https://lore.kernel.org/linux-arm-kernel/1605236574-14636-1-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. > > If your patch fixes the randomisation issue that Ard addressed, I'm > happy to replace that with your patch. But please post a new version and > get some acks in place from the parties involved in the discussion.
The above patch is not a replacement for Ard's randomization patch here but rather complements it. Hence both these patches should be considered, which will make memory hotplug better on the platform.
| |