On 01/03/2017 11:24 AM, Dan Williams wrote: > On Tue, Jan 3, 2017 at 12:31 AM, Baoquan He <b...@redhat.com> wrote: >> Hi Dan, >> >> On 11/22/16 at 09:26am, Dan Williams wrote: >>> [ replying for Dave since he's offline today and tomorrow ] >>> >>> On Tue, Nov 22, 2016 at 12:47 AM, Ingo Molnar <mi...@kernel.org> wrote: >>>> >>>> * Dave Jiang <dave.ji...@intel.com> wrote: >>>> >>>>> CONFIG_RANDOMIZE_BASE relocates the kernel to a random base address. >>>>> However it does not take into account the memmap= parameter passed in from >>>>> the kernel commandline. >>>> >>>> memmap= parameters are often used as a list. >>>> >>>>> [...] This results in the kernel sometimes being put in the middle of the >>>>> user >>>>> memmap. [...] >>>> >>>> What does this mean? If memmap= is used to re-define the memory map then >>>> the >>>> kernel getting in the middle of a RAM area is what we want, isn't it? What >>>> we >>>> don't want is for the kernel to get into reserved areas, right? >>> >>> Right, this is about teaching kaslr to not land the kernel in newly >>> defined reserved regions that were not marked reserved in the initial >>> e820 map from platform firmware. >> >> If only tell kaslr to not land kernel in newly defined reserved regions, >> memory added by "memmap=nn[KMG]@ss[KMG]" should not be avoided since >> it's usable memory. Kernel randomized into this region is also what we >> want. Not sure if I understand it right. > > You're right, this is supposed to be for memmap=nn!ss cases which > defines reserved persistent memory ranges, not memmap=nn@ss which > defines usable memory. > > We need to fix mem_avoid_memmap() to only skip memmap= statements that > specify reserved memory. >
I think nn@ss is the only one that we should skip over, otherwise everything else looks like should be avoided. I'll update.
