Speedup mremap on ppc64

Started by Aneesh Kumar K.V on Mar 15, 2021 · 10 messages from 4 authors · Last reply Mar 22, 2021

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6 patches, 7 files

+133 −63

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STALE2057d SUPERSEDED

Status: Superseded by v8 (posted 2021-06-16). [go to v8]

Revision v2 (7 revisions archived).

Revisions (7)
  1. v2 current
  2. v3 [diff against previous]
  3. v4 [diff against previous]
  4. v5 [diff against previous]
  5. v6 [diff against previous]
  6. v7 [diff against previous]
  7. v8 [diff against previous]

open the first message on its own page

  1. [PATCH v2 1/6] selftest/mremap_test: Update the test to handle pagesize other than 4K
    Revisions and related patches
    Revisions (7)
    1. v2 current
    2. v3 [diff against previous]
    3. v4 [diff against previous]
    4. v5 [diff against previous]
    5. v6 [diff against previous]
    6. v7 [diff against previous]
    7. v8 [diff against previous]
  2. [PATCH v2 3/6] mm/mremap: Use pmd/pud_poplulate to update page table entries
    Revisions and related patches
    Revisions (7)
    1. v2 current
    2. v3 [diff against previous]
    3. v4 [diff against previous]
    4. v5 [diff against previous]
    5. v6 [diff against previous]
    6. v7 [diff against previous]
    7. v8 [diff against previous]
  3. [PATCH v2 5/6] mm/mremap: Allow arch runtime override
    Revisions and related patches
    Revisions (6)
    1. v2 current
    2. v3 [diff against previous]
    3. v4 [diff against previous]
    4. v5 [diff against previous]
    5. v6 [diff against previous]
    6. v7 [diff against previous]
  4. [PATCH v2 4/6] mm/mremap: Use mmu gather interface instead of flush_tlb_range
    Revisions and related patches
    Revisions (6)
    1. v2 current
    2. v3 [diff against previous]
    3. v4 [diff against previous]
    4. v5 [diff against previous]
    5. v6 [diff against previous]
    6. v7 [diff against previous]
  5. [PATCH v2 2/6] selftest/mremap_test: Avoid crash with static build
    Revisions and related patches
    Revisions (7)
    1. v2 current
    2. v3 [diff against previous]
    3. v4 [diff against previous]
    4. v5 [diff against previous]
    5. v6 [diff against previous]
    6. v7 [diff against previous]
    7. v8 [diff against previous]
  6. [PATCH v2 6/6] powerpc/mm: Enable move pmd/pud
    Revisions and related patches
    Revisions (6)
    1. v2 current
    2. v3 [diff against previous]
    3. v4 [diff against previous]
    4. v5 [diff against previous]
    5. v6 [diff against previous]
    6. v7 [diff against previous]
Message details and related content
This patchset enables MOVE_PMD/MOVE_PUD support on power. This requires
the platform to support updating higher-level page tables without
updating page table entries. This also needs to invalidate the Page Walk
Cache on architecture supporting the same.

The patchset does that by switching the page table update to use mmu gather
interface instead of direct tlb flush. mmu gather allows the architecture
to manage page walk cache invalidate separately.

Changes from V1:
* Rebase to recent upstream
* Fix build issues with tlb_gather_mmu changes


Aneesh Kumar K.V (6):
  selftest/mremap_test: Update the test to handle pagesize other than 4K
  selftest/mremap_test: Avoid crash with static build
  mm/mremap: Use pmd/pud_poplulate to update page table entries
  mm/mremap: Use mmu gather interface instead of flush_tlb_range
  mm/mremap: Allow arch runtime override
  powerpc/mm: Enable move pmd/pud

 arch/arc/include/asm/tlb.h               |   5 +
 arch/arm64/include/asm/tlb.h             |   6 ++
 arch/powerpc/include/asm/tlb.h           |   6 ++
 arch/powerpc/platforms/Kconfig.cputype   |   2 +
 arch/x86/include/asm/tlb.h               |   5 +
 mm/mremap.c                              |  54 +++++++++--
 tools/testing/selftests/vm/mremap_test.c | 118 ++++++++++++-----------
 7 files changed, 133 insertions(+), 63 deletions(-)

-- 
2.29.2

[PATCH v2 1/6] selftest/mremap_test: Update the test to handle pagesize other than 4K

Message details and related content
Instead of hardcoding 4K page size fetch it using sysconf(). For the performance
measurements test still assume 2M and 1G are hugepage sizes.

Signed-off-by: Aneesh Kumar K.V <redacted>
---
 tools/testing/selftests/vm/mremap_test.c | 113 ++++++++++++-----------
 1 file changed, 61 insertions(+), 52 deletions(-)
diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c
index 9c391d016922..c9a5461eb786 100644
--- a/tools/testing/selftests/vm/mremap_test.c
+++ b/tools/testing/selftests/vm/mremap_test.c
@@ -45,14 +45,15 @@ enum {
 	_4MB = 4ULL << 20,
 	_1GB = 1ULL << 30,
 	_2GB = 2ULL << 30,
-	PTE = _4KB,
 	PMD = _2MB,
 	PUD = _1GB,
 };
 
+#define PTE page_size
+
 #define MAKE_TEST(source_align, destination_align, size,	\
 		  overlaps, should_fail, test_name)		\
-{								\
+(struct test){							\
 	.name = test_name,					\
 	.config = {						\
 		.src_alignment = source_align,			\
@@ -252,12 +253,17 @@ static int parse_args(int argc, char **argv, unsigned int *threshold_mb,
 	return 0;
 }
 
+#define MAX_TEST 13
+#define MAX_PERF_TEST 3
 int main(int argc, char **argv)
 {
 	int failures = 0;
 	int i, run_perf_tests;
 	unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD;
 	unsigned int pattern_seed;
+	struct test test_cases[MAX_TEST];
+	struct test perf_test_cases[MAX_PERF_TEST];
+	int page_size;
 	time_t t;
 
 	pattern_seed = (unsigned int) time(&t);
@@ -268,56 +274,59 @@ int main(int argc, char **argv)
 	ksft_print_msg("Test configs:\n\tthreshold_mb=%u\n\tpattern_seed=%u\n\n",
 		       threshold_mb, pattern_seed);
 
-	struct test test_cases[] = {
-		/* Expected mremap failures */
-		MAKE_TEST(_4KB, _4KB, _4KB, OVERLAPPING, EXPECT_FAILURE,
-		  "mremap - Source and Destination Regions Overlapping"),
-		MAKE_TEST(_4KB, _1KB, _4KB, NON_OVERLAPPING, EXPECT_FAILURE,
-		  "mremap - Destination Address Misaligned (1KB-aligned)"),
-		MAKE_TEST(_1KB, _4KB, _4KB, NON_OVERLAPPING, EXPECT_FAILURE,
-		  "mremap - Source Address Misaligned (1KB-aligned)"),
-
-		/* Src addr PTE aligned */
-		MAKE_TEST(PTE, PTE, _8KB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "8KB mremap - Source PTE-aligned, Destination PTE-aligned"),
-
-		/* Src addr 1MB aligned */
-		MAKE_TEST(_1MB, PTE, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "2MB mremap - Source 1MB-aligned, Destination PTE-aligned"),
-		MAKE_TEST(_1MB, _1MB, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "2MB mremap - Source 1MB-aligned, Destination 1MB-aligned"),
-
-		/* Src addr PMD aligned */
-		MAKE_TEST(PMD, PTE, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "4MB mremap - Source PMD-aligned, Destination PTE-aligned"),
-		MAKE_TEST(PMD, _1MB, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "4MB mremap - Source PMD-aligned, Destination 1MB-aligned"),
-		MAKE_TEST(PMD, PMD, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "4MB mremap - Source PMD-aligned, Destination PMD-aligned"),
-
-		/* Src addr PUD aligned */
-		MAKE_TEST(PUD, PTE, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "2GB mremap - Source PUD-aligned, Destination PTE-aligned"),
-		MAKE_TEST(PUD, _1MB, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "2GB mremap - Source PUD-aligned, Destination 1MB-aligned"),
-		MAKE_TEST(PUD, PMD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "2GB mremap - Source PUD-aligned, Destination PMD-aligned"),
-		MAKE_TEST(PUD, PUD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "2GB mremap - Source PUD-aligned, Destination PUD-aligned"),
-	};
-
-	struct test perf_test_cases[] = {
-		/*
-		 * mremap 1GB region - Page table level aligned time
-		 * comparison.
-		 */
-		MAKE_TEST(PTE, PTE, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "1GB mremap - Source PTE-aligned, Destination PTE-aligned"),
-		MAKE_TEST(PMD, PMD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "1GB mremap - Source PMD-aligned, Destination PMD-aligned"),
-		MAKE_TEST(PUD, PUD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
-		  "1GB mremap - Source PUD-aligned, Destination PUD-aligned"),
-	};
+	page_size = sysconf(_SC_PAGESIZE);
+
+	/* Expected mremap failures */
+	test_cases[0] =	MAKE_TEST(page_size, page_size, page_size,
+				  OVERLAPPING, EXPECT_FAILURE,
+				  "mremap - Source and Destination Regions Overlapping");
+
+	test_cases[1] = MAKE_TEST(page_size, page_size/4, page_size,
+				  NON_OVERLAPPING, EXPECT_FAILURE,
+				  "mremap - Destination Address Misaligned (1KB-aligned)");
+	test_cases[2] = MAKE_TEST(page_size/4, page_size, page_size,
+				  NON_OVERLAPPING, EXPECT_FAILURE,
+				  "mremap - Source Address Misaligned (1KB-aligned)");
+
+	/* Src addr PTE aligned */
+	test_cases[3] = MAKE_TEST(PTE, PTE, PTE * 2,
+				  NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "8KB mremap - Source PTE-aligned, Destination PTE-aligned");
+
+	/* Src addr 1MB aligned */
+	test_cases[4] = MAKE_TEST(_1MB, PTE, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "2MB mremap - Source 1MB-aligned, Destination PTE-aligned");
+	test_cases[5] = MAKE_TEST(_1MB, _1MB, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "2MB mremap - Source 1MB-aligned, Destination 1MB-aligned");
+
+	/* Src addr PMD aligned */
+	test_cases[6] = MAKE_TEST(PMD, PTE, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "4MB mremap - Source PMD-aligned, Destination PTE-aligned");
+	test_cases[7] =	MAKE_TEST(PMD, _1MB, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "4MB mremap - Source PMD-aligned, Destination 1MB-aligned");
+	test_cases[8] = MAKE_TEST(PMD, PMD, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "4MB mremap - Source PMD-aligned, Destination PMD-aligned");
+
+	/* Src addr PUD aligned */
+	test_cases[9] = MAKE_TEST(PUD, PTE, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "2GB mremap - Source PUD-aligned, Destination PTE-aligned");
+	test_cases[10] = MAKE_TEST(PUD, _1MB, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				   "2GB mremap - Source PUD-aligned, Destination 1MB-aligned");
+	test_cases[11] = MAKE_TEST(PUD, PMD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				   "2GB mremap - Source PUD-aligned, Destination PMD-aligned");
+	test_cases[12] = MAKE_TEST(PUD, PUD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				   "2GB mremap - Source PUD-aligned, Destination PUD-aligned");
+
+	perf_test_cases[0] =  MAKE_TEST(page_size, page_size, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+					"1GB mremap - Source PTE-aligned, Destination PTE-aligned");
+	/*
+	 * mremap 1GB region - Page table level aligned time
+	 * comparison.
+	 */
+	perf_test_cases[1] = MAKE_TEST(PMD, PMD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				       "1GB mremap - Source PMD-aligned, Destination PMD-aligned");
+	perf_test_cases[2] = MAKE_TEST(PUD, PUD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				       "1GB mremap - Source PUD-aligned, Destination PUD-aligned");
 
 	run_perf_tests =  (threshold_mb == VALIDATION_NO_THRESHOLD) ||
 				(threshold_mb * _1MB >= _1GB);
-- 
2.29.2

[PATCH v2 3/6] mm/mremap: Use pmd/pud_poplulate to update page table entries

Message details and related content
pmd/pud_populate is the right interface to be used to set the respective
page table entries. Some architectures like ppc64 do assume that set_pmd/pud_at
can only be used to set a hugepage PTE. Since we are not setting up a hugepage
PTE here, use the pmd/pud_populate interface.

Signed-off-by: Aneesh Kumar K.V <redacted>
---
 mm/mremap.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c
index ec8f840399ed..574287f9bb39 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -26,6 +26,7 @@
 
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
+#include <asm/pgalloc.h>
 
 #include "internal.h"
 
@@ -257,9 +258,8 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 	pmd_clear(old_pmd);
 
 	VM_BUG_ON(!pmd_none(*new_pmd));
+	pmd_populate(mm, new_pmd, (pgtable_t)pmd_page_vaddr(pmd));
 
-	/* Set the new pmd */
-	set_pmd_at(mm, new_addr, new_pmd, pmd);
 	flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
 	if (new_ptl != old_ptl)
 		spin_unlock(new_ptl);
@@ -306,8 +306,7 @@ static bool move_normal_pud(struct vm_area_struct *vma, unsigned long old_addr,
 
 	VM_BUG_ON(!pud_none(*new_pud));
 
-	/* Set the new pud */
-	set_pud_at(mm, new_addr, new_pud, pud);
+	pud_populate(mm, new_pud, (pmd_t *)pud_page_vaddr(pud));
 	flush_tlb_range(vma, old_addr, old_addr + PUD_SIZE);
 	if (new_ptl != old_ptl)
 		spin_unlock(new_ptl);
-- 
2.29.2

[PATCH v2 5/6] mm/mremap: Allow arch runtime override

Message details and related content
Architectures like ppc64 can only support faster mremap only with radix
translation. Hence allow a runtime check w.r.t support for fast mremap.

Signed-off-by: Aneesh Kumar K.V <redacted>
---
 arch/arc/include/asm/tlb.h     |  5 +++++
 arch/arm64/include/asm/tlb.h   |  6 ++++++
 arch/powerpc/include/asm/tlb.h |  6 ++++++
 arch/x86/include/asm/tlb.h     |  5 +++++
 mm/mremap.c                    | 14 +++++++++++++-
 5 files changed, 35 insertions(+), 1 deletion(-)
diff --git a/arch/arc/include/asm/tlb.h b/arch/arc/include/asm/tlb.h
index 975b35d3738d..22b8cfb46cbf 100644
--- a/arch/arc/include/asm/tlb.h
+++ b/arch/arc/include/asm/tlb.h
@@ -9,4 +9,9 @@
 #include <linux/pagemap.h>
 #include <asm-generic/tlb.h>
 
+#define arch_supports_page_tables_move arch_supports_page_tables_move
+static inline bool arch_supports_page_tables_move(void)
+{
+	return true;
+}
 #endif /* _ASM_ARC_TLB_H */
diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index 61c97d3b58c7..fe209efc6a10 100644
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -94,4 +94,10 @@ static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pudp,
 }
 #endif
 
+#define arch_supports_page_tables_move arch_supports_page_tables_move
+static inline bool arch_supports_page_tables_move(void)
+{
+	return true;
+}
+
 #endif
diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/asm/tlb.h
index 160422a439aa..058918a7cd3c 100644
--- a/arch/powerpc/include/asm/tlb.h
+++ b/arch/powerpc/include/asm/tlb.h
@@ -83,5 +83,11 @@ static inline int mm_is_thread_local(struct mm_struct *mm)
 }
 #endif
 
+#define arch_supports_page_tables_move arch_supports_page_tables_move
+static inline bool arch_supports_page_tables_move(void)
+{
+	return radix_enabled();
+}
+
 #endif /* __KERNEL__ */
 #endif /* __ASM_POWERPC_TLB_H */
diff --git a/arch/x86/include/asm/tlb.h b/arch/x86/include/asm/tlb.h
index 1bfe979bb9bc..62915238bb36 100644
--- a/arch/x86/include/asm/tlb.h
+++ b/arch/x86/include/asm/tlb.h
@@ -37,4 +37,9 @@ static inline void __tlb_remove_table(void *table)
 	free_page_and_swap_cache(table);
 }
 
+#define arch_supports_page_tables_move arch_supports_page_tables_move
+static inline bool arch_supports_page_tables_move(void)
+{
+	return true;
+}
 #endif /* _ASM_X86_TLB_H */
diff --git a/mm/mremap.c b/mm/mremap.c
index fafa73b965d3..316181822cce 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -25,7 +25,7 @@
 #include <linux/userfaultfd_k.h>
 
 #include <asm/cacheflush.h>
-#include <asm/tlbflush.h>
+#include <asm/tlb.h>
 #include <asm/pgalloc.h>
 
 #include "internal.h"
@@ -210,6 +210,14 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
 		drop_rmap_locks(vma);
 }
 
+#ifndef arch_supports_page_tables_move
+#define arch_supports_page_tables_move arch_supports_page_tables_move
+static inline bool arch_supports_page_tables_move(void)
+{
+	return false;
+}
+#endif
+
 #ifdef CONFIG_HAVE_MOVE_PMD
 static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		  unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
@@ -219,6 +227,8 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 	struct mmu_gather tlb;
 	pmd_t pmd;
 
+	if (!arch_supports_page_tables_move())
+		return false;
 	/*
 	 * The destination pmd shouldn't be established, free_pgtables()
 	 * should have released it.
@@ -297,6 +307,8 @@ static bool move_normal_pud(struct vm_area_struct *vma, unsigned long old_addr,
 	struct mmu_gather tlb;
 	pud_t pud;
 
+	if (!arch_supports_page_tables_move())
+		return false;
 	/*
 	 * The destination pud shouldn't be established, free_pgtables()
 	 * should have released it.
-- 
2.29.2

[PATCH v2 4/6] mm/mremap: Use mmu gather interface instead of flush_tlb_range

Message details and related content
Some architectures do have the concept of page walk cache and only mmu gather
interface supports flushing them. A fast mremap that involves moving page
table pages instead of copying pte entries should flush page walk cache since
the old translation cache is no more valid. Hence switch to mm gather to flush
TLB and mark tlb.freed_tables = 1. No page table pages need to be freed here.
With this the tlb flush is done outside page table lock (ptl).

Signed-off-by: Aneesh Kumar K.V <redacted>
---
 mm/mremap.c | 33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c
index 574287f9bb39..fafa73b965d3 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -216,6 +216,7 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 {
 	spinlock_t *old_ptl, *new_ptl;
 	struct mm_struct *mm = vma->vm_mm;
+	struct mmu_gather tlb;
 	pmd_t pmd;
 
 	/*
@@ -244,11 +245,12 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 	if (WARN_ON_ONCE(!pmd_none(*new_pmd)))
 		return false;
 
+	tlb_gather_mmu(&tlb, mm);
 	/*
 	 * We don't have to worry about the ordering of src and dst
 	 * ptlocks because exclusive mmap_lock prevents deadlock.
 	 */
-	old_ptl = pmd_lock(vma->vm_mm, old_pmd);
+	old_ptl = pmd_lock(mm, old_pmd);
 	new_ptl = pmd_lockptr(mm, new_pmd);
 	if (new_ptl != old_ptl)
 		spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
@@ -257,13 +259,23 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 	pmd = *old_pmd;
 	pmd_clear(old_pmd);
 
+	/*
+	 * Mark the range. We are not freeing page table pages nor
+	 * regular pages. Hence we don't need to call tlb_remove_table()
+	 * or tlb_remove_page().
+	 */
+	tlb_flush_pte_range(&tlb, old_addr, PMD_SIZE);
+	tlb.freed_tables = 1;
 	VM_BUG_ON(!pmd_none(*new_pmd));
 	pmd_populate(mm, new_pmd, (pgtable_t)pmd_page_vaddr(pmd));
 
-	flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
 	if (new_ptl != old_ptl)
 		spin_unlock(new_ptl);
 	spin_unlock(old_ptl);
+	/*
+	 * This will invalidate both the old TLB and page table walk caches.
+	 */
+	tlb_finish_mmu(&tlb);
 
 	return true;
 }
@@ -282,6 +294,7 @@ static bool move_normal_pud(struct vm_area_struct *vma, unsigned long old_addr,
 {
 	spinlock_t *old_ptl, *new_ptl;
 	struct mm_struct *mm = vma->vm_mm;
+	struct mmu_gather tlb;
 	pud_t pud;
 
 	/*
@@ -291,11 +304,12 @@ static bool move_normal_pud(struct vm_area_struct *vma, unsigned long old_addr,
 	if (WARN_ON_ONCE(!pud_none(*new_pud)))
 		return false;
 
+	tlb_gather_mmu(&tlb, mm);
 	/*
 	 * We don't have to worry about the ordering of src and dst
 	 * ptlocks because exclusive mmap_lock prevents deadlock.
 	 */
-	old_ptl = pud_lock(vma->vm_mm, old_pud);
+	old_ptl = pud_lock(mm, old_pud);
 	new_ptl = pud_lockptr(mm, new_pud);
 	if (new_ptl != old_ptl)
 		spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
@@ -304,14 +318,25 @@ static bool move_normal_pud(struct vm_area_struct *vma, unsigned long old_addr,
 	pud = *old_pud;
 	pud_clear(old_pud);
 
+	/*
+	 * Mark the range. We are not freeing page table pages nor
+	 * regular pages. Hence we don't need to call tlb_remove_table()
+	 * or tlb_remove_page().
+	 */
+	tlb_flush_pte_range(&tlb, old_addr, PUD_SIZE);
+	tlb.freed_tables = 1;
 	VM_BUG_ON(!pud_none(*new_pud));
 
 	pud_populate(mm, new_pud, (pmd_t *)pud_page_vaddr(pud));
-	flush_tlb_range(vma, old_addr, old_addr + PUD_SIZE);
+
 	if (new_ptl != old_ptl)
 		spin_unlock(new_ptl);
 	spin_unlock(old_ptl);
 
+	/*
+	 * This will invalidate both the old TLB and page table walk caches.
+	 */
+	tlb_finish_mmu(&tlb);
 	return true;
 }
 #else
-- 
2.29.2

[PATCH v2 2/6] selftest/mremap_test: Avoid crash with static build

Message details and related content
With a large mmap map size, we can overlap with the text area and using
MAP_FIXED results in unmapping that area. Switch to MAP_FIXED_NOREPLACE
and handle the EEXIST error.

Signed-off-by: Aneesh Kumar K.V <redacted>
---
 tools/testing/selftests/vm/mremap_test.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c
index c9a5461eb786..0624d1bd71b5 100644
--- a/tools/testing/selftests/vm/mremap_test.c
+++ b/tools/testing/selftests/vm/mremap_test.c
@@ -75,9 +75,10 @@ static void *get_source_mapping(struct config c)
 retry:
 	addr += c.src_alignment;
 	src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE,
-			MAP_FIXED | MAP_ANONYMOUS | MAP_SHARED, -1, 0);
+			MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
+			-1, 0);
 	if (src_addr == MAP_FAILED) {
-		if (errno == EPERM)
+		if (errno == EPERM || errno == EEXIST)
 			goto retry;
 		goto error;
 	}
-- 
2.29.2

[PATCH v2 6/6] powerpc/mm: Enable move pmd/pud

Message details and related content
mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region:
1GB mremap - Source PTE-aligned, Destination PTE-aligned
        mremap time:      1114318ns
1GB mremap - Source PMD-aligned, Destination PMD-aligned
        mremap time:      1097715ns
1GB mremap - Source PUD-aligned, Destination PUD-aligned
        mremap time:        26851ns

Signed-off-by: Aneesh Kumar K.V <redacted>
---
 arch/powerpc/platforms/Kconfig.cputype | 2 ++
 1 file changed, 2 insertions(+)
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 3ce907523b1e..2e666e569fdf 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -97,6 +97,8 @@ config PPC_BOOK3S_64
 	select PPC_HAVE_PMU_SUPPORT
 	select SYS_SUPPORTS_HUGETLBFS
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
+	select HAVE_MOVE_PMD
+	select HAVE_MOVE_PUD
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
 	select ARCH_SUPPORTS_NUMA_BALANCING
 	select IRQ_WORK
-- 
2.29.2

Re: [PATCH v2 4/6] mm/mremap: Use mmu gather interface instead of flush_tlb_range

Message details and related content
Hi "Aneesh,

I love your patch! Yet something to improve:

[auto build test ERROR on powerpc/next]
[also build test ERROR on kselftest/next v5.12-rc3 next-20210317]
[cannot apply to hnaz-linux-mm/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Aneesh-Kumar-K-V/Speedup-mremap-on-ppc64/20210315-194324
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: x86_64-rhel-8.3 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/d3b9a3e6f414413d8f822185158b937d9f19b7a6
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Aneesh-Kumar-K-V/Speedup-mremap-on-ppc64/20210315-194324
        git checkout d3b9a3e6f414413d8f822185158b937d9f19b7a6
        # save the attached .config to linux build tree
        make W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

Note: the linux-review/Aneesh-Kumar-K-V/Speedup-mremap-on-ppc64/20210315-194324 HEAD 79633714ff2b990b3e4972873457678bb34d029f builds fine.
      It only hurts bisectibility.

All errors (new ones prefixed by >>):

   mm/mremap.c: In function 'move_normal_pmd':
quoted
mm/mremap.c:219:20: error: storage size of 'tlb' isn't known
     219 |  struct mmu_gather tlb;
         |                    ^~~
quoted
mm/mremap.c:267:2: error: implicit declaration of function 'tlb_flush_pte_range' [-Werror=implicit-function-declaration]
     267 |  tlb_flush_pte_range(&tlb, old_addr, PMD_SIZE);
         |  ^~~~~~~~~~~~~~~~~~~
   mm/mremap.c:219:20: warning: unused variable 'tlb' [-Wunused-variable]
     219 |  struct mmu_gather tlb;
         |                    ^~~
   mm/mremap.c: In function 'move_normal_pud':
   mm/mremap.c:297:20: error: storage size of 'tlb' isn't known
     297 |  struct mmu_gather tlb;
         |                    ^~~
   mm/mremap.c:297:20: warning: unused variable 'tlb' [-Wunused-variable]
   cc1: some warnings being treated as errors


vim +219 mm/mremap.c

   212	
   213	#ifdef CONFIG_HAVE_MOVE_PMD
   214	static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
   215			  unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
   216	{
   217		spinlock_t *old_ptl, *new_ptl;
   218		struct mm_struct *mm = vma->vm_mm;
 > 219		struct mmu_gather tlb;
   220		pmd_t pmd;
   221	
   222		/*
   223		 * The destination pmd shouldn't be established, free_pgtables()
   224		 * should have released it.
   225		 *
   226		 * However, there's a case during execve() where we use mremap
   227		 * to move the initial stack, and in that case the target area
   228		 * may overlap the source area (always moving down).
   229		 *
   230		 * If everything is PMD-aligned, that works fine, as moving
   231		 * each pmd down will clear the source pmd. But if we first
   232		 * have a few 4kB-only pages that get moved down, and then
   233		 * hit the "now the rest is PMD-aligned, let's do everything
   234		 * one pmd at a time", we will still have the old (now empty
   235		 * of any 4kB pages, but still there) PMD in the page table
   236		 * tree.

58 more lines

Re: [PATCH v2 4/6] mm/mremap: Use mmu gather interface instead of flush_tlb_range

Message details and related content
Excerpts from Aneesh Kumar K.V's message of March 15, 2021 9:38 pm:
Some architectures do have the concept of page walk cache and only mmu gather
interface supports flushing them. A fast mremap that involves moving page
table pages instead of copying pte entries should flush page walk cache since
the old translation cache is no more valid. Hence switch to mm gather to flush
TLB and mark tlb.freed_tables = 1. No page table pages need to be freed here.
With this the tlb flush is done outside page table lock (ptl).
I would maybe just get archs that implement it to provide a specific
flush_tlb+pwc_range for it, or else they get flush_tlb_range by default.

I think that would be simpler for now, at least in generic code.

There was some other talk of consolidating the TLB flush APIs, I jsut 
don't know if it's the best way to go to use the page/page table 
gathering and freeing API for it.

Thanks,
Nick
quoted hunk
Signed-off-by: Aneesh Kumar K.V <redacted>
---
 mm/mremap.c | 33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c
index 574287f9bb39..fafa73b965d3 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -216,6 +216,7 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 {
 	spinlock_t *old_ptl, *new_ptl;
 	struct mm_struct *mm = vma->vm_mm;
+	struct mmu_gather tlb;
 	pmd_t pmd;
 
 	/*
@@ -244,11 +245,12 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 	if (WARN_ON_ONCE(!pmd_none(*new_pmd)))
 		return false;
 
+	tlb_gather_mmu(&tlb, mm);
 	/*
 	 * We don't have to worry about the ordering of src and dst
 	 * ptlocks because exclusive mmap_lock prevents deadlock.
 	 */
-	old_ptl = pmd_lock(vma->vm_mm, old_pmd);
+	old_ptl = pmd_lock(mm, old_pmd);
 	new_ptl = pmd_lockptr(mm, new_pmd);
 	if (new_ptl != old_ptl)
 		spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
@@ -257,13 +259,23 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 	pmd = *old_pmd;
 	pmd_clear(old_pmd);
 
+	/*
+	 * Mark the range. We are not freeing page table pages nor
+	 * regular pages. Hence we don't need to call tlb_remove_table()
+	 * or tlb_remove_page().

70 more quoted lines

[mm/mremap] c10e9d3441: Bad_pagetable:#[##]

Message details and related content

Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: c10e9d3441ddee43a36482980f1e39efbd5169e2 ("[PATCH v2 3/6] mm/mremap: Use pmd/pud_poplulate to update page table entries")
url: https://github.com/0day-ci/linux/commits/Aneesh-Kumar-K-V/Speedup-mremap-on-ppc64/20210315-194324
base: https://git.kernel.org/cgit/linux/kernel/git/powerpc/linux.git next

in testcase: ltp
version: ltp-x86_64-14c1f76-1_20210318
with following parameters:

	test: cve
	ucode: 0xe2

test-description: The LTP testsuite contains a collection of tools for testing the Linux kernel and related features.
test-url: http://linux-test-project.github.io/


on test machine: 8 threads Intel(R) Core(TM) i7-6770HQ CPU @ 2.60GHz with 32G memory

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):



If you fix the issue, kindly add following tag
Reported-by: kernel test robot <redacted>


[   98.252964] INFO: creating /lkp/benchmarks/ltp/output directory
[   98.252970]
[   98.267491] INFO: creating /lkp/benchmarks/ltp/results directory
[   98.267497]
[   98.281384] Checking for required user/group ids
[   98.281391]
[   98.291431]
[   98.291435]
[   98.300185] 'nobody' user id and group found.

135 more lines

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