Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
From: Steven Price <steven.price@arm.com>
To: Andrew Morton <akpm@linux-foundation.org>, 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>
Subject: [PATCH v15 12/23] mm: pagewalk: Allow walking without vma
Date: Fri,  1 Nov 2019 14:09:31 +0000
Message-ID: <20191101140942.51554-13-steven.price@arm.com> (raw)
In-Reply-To: <20191101140942.51554-1-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 in the generic code and add a new
function walk_page_range_novma() which ignores the VMAs and simply walks
the page tables.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 include/linux/pagewalk.h |  5 +++++
 mm/pagewalk.c            | 44 ++++++++++++++++++++++++++++++++--------
 2 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h
index 12004b097eae..ed2bb399fac2 100644
--- a/include/linux/pagewalk.h
+++ b/include/linux/pagewalk.h
@@ -53,6 +53,7 @@ struct mm_walk_ops {
  * @ops:	operation to call during the walk
  * @mm:		mm_struct representing the target process of page table walk
  * @vma:	vma currently walked (NULL if walking outside vmas)
+ * @no_vma:	walk ignoring vmas (vma will always be NULL)
  * @private:	private data for callbacks' usage
  *
  * (see the comment on walk_page_range() for more details)
@@ -61,12 +62,16 @@ struct mm_walk {
 	const struct mm_walk_ops *ops;
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
+	bool no_vma;
 	void *private;
 };
 
 int walk_page_range(struct mm_struct *mm, unsigned long start,
 		unsigned long end, const struct mm_walk_ops *ops,
 		void *private);
+int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
+			  unsigned long end, const struct mm_walk_ops *ops,
+			  void *private);
 int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
 		void *private);
 
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index fc4d98a3a5a0..626e7fdb0508 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -38,7 +38,7 @@ 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) || (!walk->vma && !walk->no_vma)) {
 			if (ops->pte_hole)
 				err = ops->pte_hole(addr, next, walk);
 			if (err)
@@ -61,9 +61,14 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 		if (!ops->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;
@@ -84,7 +89,7 @@ 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) || (!walk->vma && !walk->no_vma)) {
 			if (ops->pte_hole)
 				err = ops->pte_hole(addr, next, walk);
 			if (err)
@@ -98,9 +103,13 @@ 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 (ops->pmd_entry || ops->pte_entry)
 			err = walk_pmd_range(pud, addr, next, walk);
@@ -358,6 +367,25 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
 	return err;
 }
 
+int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
+			  unsigned long end, const struct mm_walk_ops *ops,
+			  void *private)
+{
+	struct mm_walk walk = {
+		.ops		= ops,
+		.mm		= mm,
+		.private	= private,
+		.no_vma		= true
+	};
+
+	if (start >= end || !walk.mm)
+		return -EINVAL;
+
+	lockdep_assert_held(&walk.mm->mmap_sem);
+
+	return __walk_page_range(start, end, &walk);
+}
+
 int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
 		void *private)
 {
-- 
2.20.1



  parent reply index

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-01 14:09 [PATCH v15 00/23] Generic page walk and ptdump Steven Price
2019-11-01 14:09 ` [PATCH v15 01/23] mm: Add generic p?d_leaf() macros Steven Price
2019-11-01 14:09 ` [PATCH v15 02/23] arc: mm: Add p?d_leaf() definitions Steven Price
2019-11-01 14:09 ` [PATCH v15 03/23] arm: " Steven Price
2019-11-01 14:09 ` [PATCH v15 04/23] arm64: " Steven Price
2019-11-01 14:09 ` [PATCH v15 05/23] mips: " Steven Price
2019-11-01 14:09 ` [PATCH v15 06/23] powerpc: " Steven Price
2019-11-01 14:09 ` [PATCH v15 07/23] riscv: " Steven Price
2019-11-01 14:09 ` [PATCH v15 08/23] s390: " Steven Price
2019-11-01 14:09 ` [PATCH v15 09/23] sparc: " Steven Price
2019-11-01 14:09 ` [PATCH v15 10/23] x86: " Steven Price
2019-11-01 14:09 ` [PATCH v15 11/23] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price
2019-11-01 14:09 ` Steven Price [this message]
2019-11-01 14:09 ` [PATCH v15 13/23] mm: pagewalk: Add test_p?d callbacks Steven Price
2019-11-01 14:09 ` [PATCH v15 14/23] mm: pagewalk: Add 'depth' parameter to pte_hole Steven Price
2019-11-01 14:09 ` [PATCH v15 15/23] x86: mm: Point to struct seq_file from struct pg_state Steven Price
2019-11-01 14:09 ` [PATCH v15 16/23] x86: mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price
2019-11-01 14:09 ` [PATCH v15 17/23] x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price
2019-11-01 14:09 ` [PATCH v15 18/23] x86: mm: Convert ptdump_walk_pgd_level_core() " Steven Price
2019-11-01 14:09 ` [PATCH v15 19/23] mm: Add generic ptdump Steven Price
2019-11-01 14:09 ` [PATCH v15 20/23] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price
2019-11-01 14:09 ` [PATCH v15 21/23] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price
2019-11-01 14:09 ` [PATCH v15 22/23] arm64: mm: Display non-present entries in ptdump Steven Price
2019-11-01 14:09 ` [PATCH v15 23/23] mm: ptdump: Reduce level numbers by 1 in note_page() Steven Price
2019-11-04 19:35 ` [PATCH v15 00/23] Generic page walk and ptdump Qian Cai
2019-11-06 13:31   ` Qian Cai
2019-11-06 15:05     ` Steven Price
2019-12-03 11:02       ` David Hildenbrand
2019-12-04 14:54         ` Qian Cai
2019-12-04 14:56           ` David Hildenbrand
2019-12-04 16:32             ` Steven Price
2019-12-04 17:51               ` Thomas Hellstrom
2019-12-05 13:15               ` Qian Cai
2019-12-05 14:32                 ` Thomas Hellstrom
2019-12-05 14:38                   ` Qian Cai

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191101140942.51554-13-steven.price@arm.com \
    --to=steven.price@arm.com \
    --cc=Mark.Rutland@arm.com \
    --cc=akpm@linux-foundation.org \
    --cc=ard.biesheuvel@linaro.org \
    --cc=arnd@arndb.de \
    --cc=bp@alien8.de \
    --cc=catalin.marinas@arm.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=hpa@zytor.com \
    --cc=james.morse@arm.com \
    --cc=jglisse@redhat.com \
    --cc=kan.liang@linux.intel.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=luto@kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=will@kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git