linux-kernel - Re: [PATCHv7 08/19] x86/mm: Make PGDIR_SHIFT and PTRS_PER

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Date:   Tue, 19 Sep 2017 17:03:46 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Cyrill Gorcunov <gorcunov@...nvz.org>,
        Borislav Petkov <bp@...e.de>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv7 08/19] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D
 variable

On Mon, Sep 18, 2017 at 10:55:42AM +0000, Kirill A. Shutemov wrote:
> For boot-time switching between 4- and 5-level paging we need to be able
> to fold p4d page table level at runtime. It requires variable
> PGDIR_SHIFT and PTRS_PER_P4D.
> 
> The change doesn't affect the kernel image size much:
> 
>    text    data     bss     dec     hex filename
> 10710172        4879964  860160 16450296         fb02f8 vmlinux.before
> 10710340        4880000  860160 16450500         fb03c4 vmlinux.after
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

Fixup for the patch:

diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index a1d983a45ab0..10dcbec70ef9 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -428,7 +428,7 @@ static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
 }
 
 #define pgd_large(a) (pgtable_l5_enabled ? pgd_large(a) : p4d_large(__p4d(pgd_val(a))))
-#define pgd_none(a)  (pgtable_l5_enabled ? pgd_none(a) : pgd_none(a))
+#define pgd_none(a)  (pgtable_l5_enabled ? pgd_none(a) : p4d_none(__p4d(pgd_val(a))))
 
 static inline bool is_hypervisor_range(int idx)
 {
-- 
 Kirill A. Shutemov