Re: Boot failures with "mm/sparse: Remove CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER" on powerpc (was Re: mmotm 2018-07-10-16-50 uploaded)

Oscar Salvador [off-list ref] writes:

El dc., 11 jul. 2018 , 15:56, Pavel Tatashin [off-list ref] va
escriure:

quoted

I am OK, if this patch is removed from Baoquan's series. But, I would
still like to get rid of CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER, I
can work on this in my sparse_init re-write series. ppc64 should
really fallback safely to small chunks allocs, and if it does not
there is some existing bug. Michael please send the config that you
used.

Thank you,
Pavel
On Wed, Jul 11, 2018 at 9:37 AM Oscar Salvador
[off-list ref] wrote:

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On Wed, Jul 11, 2018 at 10:49:58PM +1000, Michael Ellerman wrote:

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akpm@linux-foundation.org writes:

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The mm-of-the-moment snapshot 2018-07-10-16-50 has been uploaded to

   http://www.ozlabs.org/~akpm/mmotm/

...

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* mm-sparse-add-a-static-variable-nr_present_sections.patch
* mm-sparsemem-defer-the-ms-section_mem_map-clearing.patch
* mm-sparsemem-defer-the-ms-section_mem_map-clearing-fix.patch
*

mm-sparse-add-a-new-parameter-data_unit_size-for-alloc_usemap_and_memmap.patch

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* mm-sparse-optimize-memmap-allocation-during-sparse_init.patch
*

mm-sparse-optimize-memmap-allocation-during-sparse_init-checkpatch-fixes.patch

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* mm-sparse-remove-config_sparsemem_alloc_mem_map_together.patch

This seems to be breaking my powerpc pseries qemu boots.

The boot log with some extra debug shows eg:

  $ make pseries_le_defconfig

Could you please share the config?
I was not able to find such config in the kernel tree.

I just roughly check, but if I checked the right place,
vmemmap_populated() checks for the section to contain the flags we are
setting in sparse_init_one_section().

Yes.

But with this patch, we populate first everything, and then we call
sparse_init_one_section() in sparse_init().
As I said I could be mistaken because I just checked the surface.

Yeah I think that's correct.

This might just be a bug in our code, let me look at it a bit.

cheers