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From: Steven Price <steven.price@arm.com>
To: linux-mm@kvack.org
Cc: "Steven Price" <steven.price@arm.com>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Arnd Bergmann" <arnd@arndb.de>, "Borislav Petkov" <bp@alien8.de>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"James Morse" <james.morse@arm.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Will Deacon" <will@kernel.org>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	"Mark Rutland" <Mark.Rutland@arm.com>,
	"Liang, Kan" <kan.liang@linux.intel.com>,
	"Andrew Morton" <akpm@linux-foundation.org>
Subject: [PATCH v10 12/22] mm: pagewalk: Allow walking without vma
Date: Wed, 31 Jul 2019 16:45:53 +0100
Message-ID: <20190731154603.41797-13-steven.price@arm.com> (raw)
In-Reply-To: <20190731154603.41797-1-steven.price@arm.com>

Since 48684a65b4e3: "mm: pagewalk: fix misbehavior of walk_page_range
for vma(VM_PFNMAP)", page_table_walk() will report any kernel area as
a hole, because it lacks a vma.

This means each arch has re-implemented page table walking when needed,
for example in the per-arch ptdump walker.

Remove the requirement to have a vma except when trying to split huge
pages.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 mm/pagewalk.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 98373a9f88b8..1cbef99e9258 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -36,7 +36,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 	do {
 again:
 		next = pmd_addr_end(addr, end);
-		if (pmd_none(*pmd) || !walk->vma) {
+		if (pmd_none(*pmd)) {
 			if (walk->pte_hole)
 				err = walk->pte_hole(addr, next, walk);
 			if (err)
@@ -59,9 +59,14 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 		if (!walk->pte_entry)
 			continue;
 
-		split_huge_pmd(walk->vma, pmd, addr);
-		if (pmd_trans_unstable(pmd))
-			goto again;
+		if (walk->vma) {
+			split_huge_pmd(walk->vma, pmd, addr);
+			if (pmd_trans_unstable(pmd))
+				goto again;
+		} else if (pmd_leaf(*pmd)) {
+			continue;
+		}
+
 		err = walk_pte_range(pmd, addr, next, walk);
 		if (err)
 			break;
@@ -81,7 +86,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 	do {
  again:
 		next = pud_addr_end(addr, end);
-		if (pud_none(*pud) || !walk->vma) {
+		if (pud_none(*pud)) {
 			if (walk->pte_hole)
 				err = walk->pte_hole(addr, next, walk);
 			if (err)
@@ -95,9 +100,13 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 				break;
 		}
 
-		split_huge_pud(walk->vma, pud, addr);
-		if (pud_none(*pud))
-			goto again;
+		if (walk->vma) {
+			split_huge_pud(walk->vma, pud, addr);
+			if (pud_none(*pud))
+				goto again;
+		} else if (pud_leaf(*pud)) {
+			continue;
+		}
 
 		if (walk->pmd_entry || walk->pte_entry)
 			err = walk_pmd_range(pud, addr, next, walk);
-- 
2.20.1


  parent reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-31 15:45 [PATCH v10 00/22] Generic page walk and ptdump Steven Price
2019-07-31 15:45 ` [PATCH v10 01/22] mm: Add generic p?d_leaf() macros Steven Price
2019-07-31 15:45 ` [PATCH v10 02/22] arc: mm: Add p?d_leaf() definitions Steven Price
2019-07-31 15:45 ` [PATCH v10 03/22] arm: " Steven Price
2019-07-31 15:45 ` [PATCH v10 04/22] arm64: " Steven Price
2019-07-31 15:45 ` [PATCH v10 05/22] mips: " Steven Price
2019-07-31 18:35   ` Paul Burton
2019-07-31 15:45 ` [PATCH v10 06/22] powerpc: " Steven Price
2019-07-31 15:45 ` [PATCH v10 07/22] riscv: " Steven Price
2019-07-31 15:45 ` [PATCH v10 08/22] s390: " Steven Price
2019-07-31 15:45 ` [PATCH v10 09/22] sparc: " Steven Price
2019-07-31 15:45 ` [PATCH v10 10/22] x86: " Steven Price
2019-07-31 15:45 ` [PATCH v10 11/22] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price
2019-07-31 15:45 ` Steven Price [this message]
2019-07-31 15:45 ` [PATCH v10 13/22] mm: pagewalk: Add test_p?d callbacks Steven Price
2019-07-31 15:45 ` [PATCH v10 14/22] mm: pagewalk: Add 'depth' parameter to pte_hole Steven Price
2019-07-31 15:45 ` [PATCH v10 15/22] x86: mm: Point to struct seq_file from struct pg_state Steven Price
2019-07-31 15:45 ` [PATCH v10 16/22] x86: mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price
2019-07-31 15:45 ` [PATCH v10 17/22] x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price
2019-07-31 15:45 ` [PATCH v10 18/22] x86: mm: Convert ptdump_walk_pgd_level_core() " Steven Price
2019-07-31 15:46 ` [PATCH v10 19/22] mm: Add generic ptdump Steven Price
2019-07-31 15:46 ` [PATCH v10 20/22] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price
2019-08-06 23:58   ` Andrew Morton
2019-08-07 12:58     ` Steven Price
2019-08-07 20:16       ` Andrew Morton
2019-07-31 15:46 ` [PATCH v10 21/22] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price
2019-07-31 15:46 ` [PATCH v10 22/22] arm64: mm: Display non-present entries in ptdump Steven Price

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