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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, alex@ghiti.fr, aou@eecs.berkeley.edu,
	ard.biesheuvel@linaro.org, arnd@arndb.de,
	benh@kernel.crashing.org, borntraeger@de.ibm.com, bp@alien8.de,
	catalin.marinas@arm.com, dave.hansen@linux.intel.com,
	davem@davemloft.net, gor@linux.ibm.com,
	heiko.carstens@de.ibm.com, hpa@zytor.com, james.morse@arm.com,
	jglisse@redhat.com, jhogan@kernel.org, kan.liang@linux.intel.com,
	linux-mm@kvack.org, linux@armlinux.org.uk, luto@kernel.org,
	mark.rutland@arm.com, mingo@redhat.com,
	mm-commits@vger.kernel.org, mpe@ellerman.id.au,
	paul.burton@mips.com, paul.walmsley@sifive.com, paulus@samba.org,
	peterz@infradead.org, ralf@linux-mips.org, steven.price@arm.com,
	tglx@linutronix.de, torvalds@linux-foundation.org,
	vgupta@synopsys.com, will@kernel.org, zong.li@sifive.com
Subject: [patch 35/67] mm: pagewalk: allow walking without vma
Date: Mon, 03 Feb 2020 17:35:50 -0800
Message-ID: <20200204013550._5CR33Gg1%akpm@linux-foundation.org> (raw)
In-Reply-To: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org>

From: Steven Price <steven.price@arm.com>
Subject: mm: pagewalk: allow walking without vma

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.

Link: http://lkml.kernel.org/r/20191218162402.45610-13-steven.price@arm.com
Signed-off-by: Steven Price <steven.price@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zong Li <zong.li@sifive.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/pagewalk.h |    5 ++++
 mm/pagewalk.c            |   40 +++++++++++++++++++++++++++++--------
 2 files changed, 37 insertions(+), 8 deletions(-)

--- a/include/linux/pagewalk.h~mm-pagewalk-allow-walking-without-vma
+++ a/include/linux/pagewalk.h
@@ -73,6 +73,7 @@ enum page_walk_action {
  * @mm:		mm_struct representing the target process of page table walk
  * @vma:	vma currently walked (NULL if walking outside vmas)
  * @action:	next action to perform (see enum page_walk_action)
+ * @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)
@@ -82,12 +83,16 @@ struct mm_walk {
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
 	enum page_walk_action action;
+	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);
 int walk_page_mapping(struct address_space *mapping, pgoff_t first_index,
--- a/mm/pagewalk.c~mm-pagewalk-allow-walking-without-vma
+++ a/mm/pagewalk.c
@@ -39,7 +39,7 @@ static int walk_pmd_range(pud_t *pud, un
 	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)
@@ -65,13 +65,16 @@ again:
 		 * Check this here so we only break down trans_huge
 		 * pages when we _need_ to
 		 */
-		if (walk->action == ACTION_CONTINUE ||
+		if ((!walk->vma && (pmd_leaf(*pmd) || !pmd_present(*pmd))) ||
+		    walk->action == ACTION_CONTINUE ||
 		    !(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;
+		}
 
 		err = walk_pte_range(pmd, addr, next, walk);
 		if (err)
@@ -93,7 +96,7 @@ static int walk_pud_range(p4d_t *p4d, un
 	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)
@@ -111,11 +114,13 @@ static int walk_pud_range(p4d_t *p4d, un
 		if (walk->action == ACTION_AGAIN)
 			goto again;
 
-		if (walk->action == ACTION_CONTINUE ||
+		if ((!walk->vma && (pud_leaf(*pud) || !pud_present(*pud))) ||
+		    walk->action == ACTION_CONTINUE ||
 		    !(ops->pmd_entry || ops->pte_entry))
 			continue;
 
-		split_huge_pud(walk->vma, pud, addr);
+		if (walk->vma)
+			split_huge_pud(walk->vma, pud, addr);
 		if (pud_none(*pud))
 			goto again;
 
@@ -389,6 +394,25 @@ int walk_page_range(struct mm_struct *mm
 	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)
 {
_


  parent reply index

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-04  1:33 incoming Andrew Morton
2020-02-04  1:33 ` [patch 01/67] ocfs2: fix oops when writing cloned file Andrew Morton
2020-02-04  1:33 ` [patch 02/67] mm/page_alloc.c: fix uninitialized memmaps on a partially populated last section Andrew Morton
2020-02-04  1:33 ` [patch 03/67] fs/proc/page.c: allow inspection of last section and fix end detection Andrew Morton
2020-02-04  1:33 ` [patch 04/67] mm/page_alloc.c: initialize memmap of unavailable memory directly Andrew Morton
2020-02-04  1:33 ` [patch 05/67] mm/page_alloc: fix and rework pfn handling in memmap_init_zone() Andrew Morton
2020-02-04  2:45   ` Linus Torvalds
2020-02-04  1:34 ` [patch 06/67] mm: factor out next_present_section_nr() Andrew Morton
2020-02-04  3:04   ` Linus Torvalds
2020-02-04  4:29     ` Andrew Morton
2020-02-04  8:22     ` David Hildenbrand
2020-02-04  1:34 ` [patch 07/67] mm/memmap_init: update variable name in memmap_init_zone Andrew Morton
2020-02-04  1:34 ` [patch 08/67] mm/memory_hotplug: poison memmap in remove_pfn_range_from_zone() Andrew Morton
2020-02-04  1:34 ` [patch 09/67] mm/memory_hotplug: we always have a zone in find_(smallest|biggest)_section_pfn Andrew Morton
2020-02-04  1:34 ` [patch 10/67] mm/memory_hotplug: don't check for "all holes" in shrink_zone_span() Andrew Morton
2020-02-04  1:34 ` [patch 11/67] mm/memory_hotplug: drop local variables " Andrew Morton
2020-02-04  1:34 ` [patch 12/67] mm/memory_hotplug: cleanup __remove_pages() Andrew Morton
2020-02-04  1:34 ` [patch 13/67] mm/memory_hotplug: drop valid_start/valid_end from test_pages_in_a_zone() Andrew Morton
2020-02-04  1:34 ` [patch 14/67] smp_mb__{before,after}_atomic(): update Documentation Andrew Morton
2020-02-04  1:34 ` [patch 15/67] ipc/mqueue.c: remove duplicated code Andrew Morton
2020-02-04  1:34 ` [patch 16/67] ipc/mqueue.c: update/document memory barriers Andrew Morton
2020-02-04  1:34 ` [patch 17/67] ipc/msg.c: update and document " Andrew Morton
2020-02-04  1:34 ` [patch 18/67] ipc/sem.c: document and update " Andrew Morton
2020-02-04  1:34 ` [patch 19/67] ipc/msg.c: consolidate all xxxctl_down() functions Andrew Morton
2020-02-04  1:34 ` [patch 20/67] drivers/block/null_blk_main.c: fix layout Andrew Morton
2020-02-04  1:34 ` [patch 21/67] drivers/block/null_blk_main.c: fix uninitialized var warnings Andrew Morton
2020-02-04  1:34 ` [patch 22/67] pinctrl: fix pxa2xx.c build warnings Andrew Morton
2020-02-04  1:34 ` [patch 23/67] mm: remove __krealloc Andrew Morton
2020-02-04  1:35 ` [patch 24/67] mm: add generic p?d_leaf() macros Andrew Morton
2020-02-04  1:35 ` [patch 25/67] arc: mm: add p?d_leaf() definitions Andrew Morton
2020-02-04  1:35 ` [patch 26/67] arm: " Andrew Morton
2020-02-04  1:35 ` [patch 27/67] arm64: " Andrew Morton
2020-02-04  1:35 ` [patch 28/67] mips: " Andrew Morton
2020-02-04  1:35 ` [patch 29/67] powerpc: " Andrew Morton
2020-02-04  1:35 ` [patch 30/67] riscv: " Andrew Morton
2020-02-04  1:35 ` [patch 31/67] s390: " Andrew Morton
2020-02-04  1:35 ` [patch 32/67] sparc: " Andrew Morton
2020-02-04  1:35 ` [patch 33/67] x86: " Andrew Morton
2020-02-04  1:35 ` [patch 34/67] mm: pagewalk: add p4d_entry() and pgd_entry() Andrew Morton
2020-02-04  1:35 ` Andrew Morton [this message]
2020-02-04  1:35 ` [patch 36/67] mm: pagewalk: don't lock PTEs for walk_page_range_novma() Andrew Morton
2020-02-04  1:35 ` [patch 37/67] mm: pagewalk: fix termination condition in walk_pte_range() Andrew Morton
2020-02-04  1:36 ` [patch 38/67] mm: pagewalk: add 'depth' parameter to pte_hole Andrew Morton
2020-02-04  1:36 ` [patch 39/67] x86: mm: point to struct seq_file from struct pg_state Andrew Morton
2020-02-04  1:36 ` [patch 40/67] x86: mm+efi: convert ptdump_walk_pgd_level() to take a mm_struct Andrew Morton
2020-02-04  1:36 ` [patch 41/67] x86: mm: convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Andrew Morton
2020-02-04  1:36 ` [patch 42/67] mm: add generic ptdump Andrew Morton
2020-02-04  1:36 ` [patch 43/67] x86: mm: convert dump_pagetables to use walk_page_range Andrew Morton
2020-02-04  1:36 ` [patch 44/67] arm64: mm: convert mm/dump.c to use walk_page_range() Andrew Morton
2020-02-04  1:36 ` [patch 45/67] arm64: mm: display non-present entries in ptdump Andrew Morton
2020-02-04  1:36 ` [patch 46/67] mm: ptdump: reduce level numbers by 1 in note_page() Andrew Morton
2020-02-04  1:36 ` [patch 47/67] x86: mm: avoid allocating struct mm_struct on the stack Andrew Morton
2020-02-04  1:36 ` [patch 48/67] powerpc/mmu_gather: enable RCU_TABLE_FREE even for !SMP case Andrew Morton
2020-02-04  1:36 ` [patch 49/67] mm/mmu_gather: invalidate TLB correctly on batch allocation failure and flush Andrew Morton
2020-02-04  1:36 ` [patch 50/67] asm-generic/tlb: avoid potential double flush Andrew Morton
2020-02-04  1:36 ` [patch 51/67] asm-gemeric/tlb: remove stray function declarations Andrew Morton
2020-02-04  1:36 ` [patch 52/67] asm-generic/tlb: add missing CONFIG symbol Andrew Morton
2020-02-04  1:37 ` [patch 53/67] asm-generic/tlb: rename HAVE_RCU_TABLE_FREE Andrew Morton
2020-02-04  1:37 ` [patch 54/67] asm-generic/tlb: rename HAVE_MMU_GATHER_PAGE_SIZE Andrew Morton
2020-02-04  1:37 ` [patch 55/67] asm-generic/tlb: rename HAVE_MMU_GATHER_NO_GATHER Andrew Morton
2020-02-04  1:37 ` [patch 56/67] asm-generic/tlb: provide MMU_GATHER_TABLE_FREE Andrew Morton
2020-02-04  1:37 ` [patch 57/67] proc: decouple proc from VFS with "struct proc_ops" Andrew Morton
2020-02-04  1:37 ` [patch 58/67] proc: convert everything to " Andrew Morton
2020-02-04  1:37 ` [patch 59/67] lib/string: add strnchrnul() Andrew Morton
2020-02-04  1:37 ` [patch 60/67] bitops: more BITS_TO_* macros Andrew Morton
2020-02-04  1:37 ` [patch 61/67] lib: add test for bitmap_parse() Andrew Morton
2020-02-04  1:37 ` [patch 62/67] lib: make bitmap_parse_user a wrapper on bitmap_parse Andrew Morton
2020-02-04  1:37 ` [patch 63/67] lib: rework bitmap_parse() Andrew Morton
2020-02-04  1:37 ` [patch 64/67] lib: new testcases for bitmap_parse{_user} Andrew Morton
2020-02-04  1:37 ` [patch 65/67] include/linux/cpumask.h: don't calculate length of the input string Andrew Morton
2020-02-04  1:37 ` [patch 66/67] treewide: remove redundant IS_ERR() before error code check Andrew Morton
2020-02-04  1:37 ` [patch 67/67] ARM: dma-api: fix max_pfn off-by-one error in __dma_supported() Andrew Morton
2020-02-04  2:27 ` incoming Linus Torvalds
2020-02-04  2:46   ` incoming Andrew Morton
2020-02-04  3:11     ` incoming Linus Torvalds
2020-02-14  6:26 ` mmotm 2020-02-13-22-26 uploaded Andrew Morton
2020-02-14 16:29   ` mmotm 2020-02-13-22-26 uploaded (mm/hugetlb.c) Randy Dunlap
2020-02-14 17:18     ` Mike Kravetz
2020-02-14 20:51       ` Mina Almasry
     [not found]       ` <20200214204544.231482-1-almasrymina@google.com>
2020-02-14 21:00         ` [PATCH] hugetlb: fix CONFIG_CGROUP_HUGETLB ifdefs Mina Almasry
2020-02-15  1:17           ` Randy Dunlap
2020-02-15  1:56             ` Randy Dunlap
2020-02-16 20:40               ` Mina Almasry
2020-02-16 21:03                 ` Mina Almasry
2020-02-17  2:48                   ` Randy Dunlap
2020-02-17  2:57                     ` [PATCH] hugetlb: fix <linux/hugetlb_cgroup.h> structs Randy Dunlap
2020-02-17  3:53               ` [PATCH] hugetlb: fix CONFIG_CGROUP_HUGETLB ifdefs Stephen Rothwell
2020-02-14 16:49   ` mmotm 2020-02-13-22-26 uploaded (mm/migrate.c, hugetlb_cgroup.h) Randy Dunlap
2020-02-25  3:53 ` mmotm 2020-02-24-19-53 uploaded Andrew Morton
2020-02-25  6:16   ` mmotm 2020-02-24-19-53 uploaded (init/main.c: initrd*) Randy Dunlap
2020-02-25  6:18     ` Randy Dunlap
2020-02-25  6:21       ` Randy Dunlap
2020-02-25 16:41   ` mmotm 2020-02-24-19-53 uploaded (drivers/platform/x86/intel_pmc_core.c) Randy Dunlap
2020-02-25 17:01   ` mmotm 2020-02-24-19-53 uploaded (objtool warning) Randy Dunlap
2020-02-27 21:52     ` Josh Poimboeuf

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