Re: [PATCH v4 08/14] powerpc: add support for folded p4d page tables

[Andrew Morton]

On Tue, 14 Apr 2020 18:34:49 +0300 Mike Rapoport <rppt@xxxxxxxxxx> wrote:

> Implement primitives necessary for the 4th level folding, add walks of p4d
> level where appropriate and replace 5level-fixup.h with pgtable-nop4d.h.

A bunch of new material just landed in linux-next/powerpc.

The timing is awkward!  I trust this will be going into mainline during
this merge window?  If not, please drop it and repull after -rc1.

arch/powerpc/mm/ptdump/ptdump.c:walk_pagetables() was a problem. 
Here's what I ended up with - please check.

static void walk_pagetables(struct pg_state *st)
{
	unsigned int i;
	unsigned long addr = st->start_address & PGDIR_MASK;
	pgd_t *pgd = pgd_offset_k(addr);

	/*
	 * Traverse the linux pagetable structure and dump pages that are in
	 * the hash pagetable.
	 */
	for (i = pgd_index(addr); i < PTRS_PER_PGD; i++, pgd++, addr += PGDIR_SIZE) {
		p4d_t *p4d = p4d_offset(pgd, 0);

		if (pgd_none(*pgd) || pgd_is_leaf(*pgd))
			note_page(st, addr, 1, p4d_val(*p4d), PGDIR_SIZE);
		else if (is_hugepd(__hugepd(p4d_val(*p4d))))
			walk_hugepd(st, (hugepd_t *)pgd, addr, PGDIR_SHIFT, 1);
		else
			/* pgd exists */
			walk_pud(st, p4d, addr);
	}
}

Mike's series "mm: consolidate definitions of page table accessors"
took quite a lot of damage as well.  Patches which needed rework as a
result of this were:

powerpc-add-support-for-folded-p4d-page-tables-fix.patch
mm-introduce-include-linux-pgtableh.patch
mm-reorder-includes-after-introduction-of-linux-pgtableh.patch
mm-pgtable-add-shortcuts-for-accessing-kernel-pmd-and-pte.patch
mm-pgtable-add-shortcuts-for-accessing-kernel-pmd-and-pte-fix-2.patch
mm-consolidate-pte_index-and-pte_offset_-definitions.patch
mm-consolidate-pmd_index-and-pmd_offset-definitions.patch
mm-consolidate-pud_index-and-pud_offset-definitions.patch
mm-consolidate-pgd_index-and-pgd_offset_k-definitions.patch