linux-kernel - [PATCH v6 14/19] x86: mm: Don't display pages which aren't present in debugfs

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Date:   Tue, 26 Mar 2019 16:26:19 +0000
From:   Steven Price <steven.price@....com>
To:     linux-mm@...ck.org
Cc:     Steven Price <steven.price@....com>,
        Andy Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        James Morse <james.morse@....com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will.deacon@....com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Mark Rutland <Mark.Rutland@....com>,
        "Liang, Kan" <kan.liang@...ux.intel.com>
Subject: [PATCH v6 14/19] x86: mm: Don't display pages which aren't present in debugfs

For the /sys/kernel/debug/page_tables/ files, rather than outputing a
mostly empty line when a block of memory isn't present just skip the
line. This keeps the output shorter and will help with a future change
switching to using the generic page walk code as we no longer care about
the 'level' that the page table holes are at.

Signed-off-by: Steven Price <steven.price@....com>
---
 arch/x86/mm/dump_pagetables.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index ca270fb00805..e2b53db92c34 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -304,8 +304,8 @@ static void note_page(struct seq_file *m, struct pg_state *st,
 		/*
 		 * Now print the actual finished series
 		 */
-		if (!st->marker->max_lines ||
-		    st->lines < st->marker->max_lines) {
+		if ((cur & _PAGE_PRESENT) && (!st->marker->max_lines ||
+		    st->lines < st->marker->max_lines)) {
 			pt_dump_seq_printf(m, st->to_dmesg,
 					   "0x%0*lx-0x%0*lx   ",
 					   width, st->start_address,
@@ -321,7 +321,8 @@ static void note_page(struct seq_file *m, struct pg_state *st,
 			printk_prot(m, st->current_prot, st->level,
 				    st->to_dmesg);
 		}
-		st->lines++;
+		if (cur & _PAGE_PRESENT)
+			st->lines++;
 
 		/*
 		 * We print markers for special areas of address space,
-- 
2.20.1