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

From: Andrew Morton <akpm@linux-foundation.org>
To: Mike Rapoport <rppt@kernel.org>
Cc: Rich Felker <dalias@libc.org>,
	linux-ia64@vger.kernel.org,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	linux-sh@vger.kernel.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	linux-mm@kvack.org, Paul Mackerras <paulus@samba.org>,
	linux-hexagon@vger.kernel.org, Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu, Jonas Bonn <jonas@southpole.se>,
	linux-arch@vger.kernel.org, Brian Cain <bcain@codeaurora.org>,
	Marc Zyngier <maz@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Ley Foon Tan <ley.foon.tan@intel.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	uclinux-h8-devel@lists.sourceforge.jp,
	Fenghua Yu <fenghua.yu@intel.com>, Arnd Bergmann <arnd@arndb.de>,
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	Tony Luck <tony.luck@intel.com>,
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	Michael Ellerman <mpe@ellerman.id.au>,
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Subject: Re: [PATCH v4 08/14] powerpc: add support for folded p4d page tables
Date: Wed, 3 Jun 2020 12:05:22 -0700	[thread overview]
Message-ID: <20200603120522.7646d56a23088416a7d3fc1a@linux-foundation.org> (raw)
In-Reply-To: <20200414153455.21744-9-rppt@kernel.org>

On Tue, 14 Apr 2020 18:34:49 +0300 Mike Rapoport <rppt@kernel.org> 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

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