akpm@xxxxxxxxxxxxxxxxxxxx writes: > The mm-of-the-moment snapshot 2018-07-10-16-50 has been uploaded to > > http://www.ozlabs.org/~akpm/mmotm/ ... > * 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 > * mm-sparse-optimize-memmap-allocation-during-sparse_init.patch > * mm-sparse-optimize-memmap-allocation-during-sparse_init-checkpatch-fixes.patch > * 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 $ qemu-system-ppc64 -nographic -vga none -M pseries -m 2G -kernel vmlinux ... vmemmap_populate f000000000000000..f000000000004000, node 0 * f000000000000000..f000000001000000 allocated at c00000007e000000 hash__vmemmap_create_mapping: start 0xf000000000000000 size 0x1000000 phys 0x7e000000 vmemmap_populate f000000000000000..f000000000008000, node 0 * f000000000000000..f000000001000000 allocated at c00000007d000000 hash__vmemmap_create_mapping: start 0xf000000000000000 size 0x1000000 phys 0x7d000000 vmemmap_populate f000000000000000..f00000000000c000, node 0 * f000000000000000..f000000001000000 allocated at c00000007c000000 hash__vmemmap_create_mapping: start 0xf000000000000000 size 0x1000000 phys 0x7c000000 vmemmap_populate f000000000000000..f000000000010000, node 0 * f000000000000000..f000000001000000 allocated at c00000007b000000 hash__vmemmap_create_mapping: start 0xf000000000000000 size 0x1000000 phys 0x7b000000 vmemmap_populate f000000000000000..f000000000014000, node 0 * f000000000000000..f000000001000000 allocated at c00000007a000000 hash__vmemmap_create_mapping: start 0xf000000000000000 size 0x1000000 phys 0x7a000000 vmemmap_populate f000000000000000..f000000000018000, node 0 * f000000000000000..f000000001000000 allocated at c000000079000000 hash__vmemmap_create_mapping: start 0xf000000000000000 size 0x1000000 phys 0x79000000 vmemmap_populate f000000000000000..f00000000001c000, node 0 * f000000000000000..f000000001000000 allocated at c000000078000000 hash__vmemmap_create_mapping: start 0xf000000000000000 size 0x1000000 phys 0x78000000 vmemmap_populate f000000000000000..f000000000020000, node 0 * f000000000000000..f000000001000000 allocated at c000000077000000 hash__vmemmap_create_mapping: start 0xf000000000000000 size 0x1000000 phys 0x77000000 vmemmap_populate f000000000000000..f000000000024000, node 0 * f000000000000000..f000000001000000 allocated at c000000076000000 hash__vmemmap_create_mapping: start 0xf000000000000000 size 0x1000000 phys 0x76000000 hash__vmemmap_create_mapping: failed -1 <repeated many times> Then there's lots of other warnings about bad page states and eventually a NULL deref and we panic(). The problem seems to be that we're calling down into hash__vmemmap_create_mapping() for every call to vmemmap_populate(), whereas previously we would only call hash__vmemmap_create_mapping() once because our vmemmap_populated() would return true. There's actually a comment in sparse_init() that says: * powerpc need to call sparse_init_one_section right after each * sparse_early_mem_map_alloc, so allocate usemap_map at first. So changing that behaviour does seem to be the problem. I assume that comment is talking about the fact that we use pfn_valid() in vmemmap_populated(). I'm not clear on how to fix it though. Any ideas? cheers
