Re: [tip:x86/mm] mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y

[Kirill A. Shutemov]

On Thu, Nov 02, 2017 at 01:42:42PM +0000, Sudeep Holla wrote:
> 
> 
> On 02/11/17 13:34, Kirill A. Shutemov wrote:
> > On Thu, Nov 02, 2017 at 12:31:54PM +0000, Sudeep Holla wrote:
> >> (+Will, Catalin)
> >>
> >> On Fri, Oct 20, 2017 at 1:27 PM, tip-bot for Kirill A. Shutemov
> >> <tipbot@xxxxxxxxx> wrote:
> >>> Commit-ID:  83e3c48729d9ebb7af5a31a504f3fd6aff0348c4
> >>> Gitweb:     https://git.kernel.org/tip/83e3c48729d9ebb7af5a31a504f3fd6aff0348c4
> >>> Author:     Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> >>> AuthorDate: Fri, 29 Sep 2017 17:08:16 +0300
> >>> Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
> >>> CommitDate: Fri, 20 Oct 2017 13:07:09 +0200
> >>>
> >>> mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y
> >>>
> >>> Size of the mem_section[] array depends on the size of the physical address space.
> >>>
> >>> In preparation for boot-time switching between paging modes on x86-64
> >>> we need to make the allocation of mem_section[] dynamic, because otherwise
> >>> we waste a lot of RAM: with CONFIG_NODE_SHIFT=10, mem_section[] size is 32kB
> >>> for 4-level paging and 2MB for 5-level paging mode.
> >>>
> >>> The patch allocates the array on the first call to sparse_memory_present_with_active_regions().
> >>>
> >>
> >> I am seeing a boot failure with this patch in linux-next today(20171102)
> > 
> > Could you share the kernel config?
> > 
> 
> It's the default config on arm64. Generated file is almost 160kB, I will
> send it to you off-list.
> 
> > Have you bisected the failure to the commit?
> > 
> I just reverted this commit as I suspected that and it boots fine after
> the revert.

Could you try the patch below instead?