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Date: Wed, 10 Nov 2021 18:54:28 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: akpm@...ux-foundation.org, tglx@...utronix.de,
kirill.shutemov@...ux.intel.com, mika.penttila@...tfour.com,
david@...hat.com, jgg@...dia.com
Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, songmuchun@...edance.com,
zhouchengming@...edance.com, Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v3 15/15] mm/pte_ref: use mmu_gather to free PTE page table pages
In unmap_region() and other paths, we can reuse @tlb to
free PTE page table, which can reduce the number of tlb
flush.
Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
Documentation/vm/pte_ref.rst | 58 +++++++++++++++++++++++---------------------
arch/x86/Kconfig | 2 +-
include/linux/pte_ref.h | 34 ++++++++++++++++++++------
mm/madvise.c | 4 +--
mm/memory.c | 4 +--
mm/mmu_gather.c | 40 +++++++++++++-----------------
mm/pte_ref.c | 13 +++++++---
7 files changed, 90 insertions(+), 65 deletions(-)
diff --git a/Documentation/vm/pte_ref.rst b/Documentation/vm/pte_ref.rst
index c5323a263464..d304c0bfaae1 100644
--- a/Documentation/vm/pte_ref.rst
+++ b/Documentation/vm/pte_ref.rst
@@ -183,30 +183,34 @@ GUP as an example::
4. Helpers
==========
-+---------------------+-------------------------------------------------+
-| pte_ref_init | Initialize the pte_refcount and pmd |
-+---------------------+-------------------------------------------------+
-| pte_to_pmd | Get the corresponding pmd |
-+---------------------+-------------------------------------------------+
-| pte_update_pmd | Update the corresponding pmd |
-+---------------------+-------------------------------------------------+
-| pte_get | Increment a pte_refcount |
-+---------------------+-------------------------------------------------+
-| pte_get_many | Add a value to a pte_refcount |
-+---------------------+-------------------------------------------------+
-| pte_get_unless_zero | Increment a pte_refcount unless it is 0 |
-+---------------------+-------------------------------------------------+
-| pte_try_get | Try to increment a pte_refcount |
-+---------------------+-------------------------------------------------+
-| pte_tryget_map | Try to increment a pte_refcount before |
-| | pte_offset_map() |
-+---------------------+-------------------------------------------------+
-| pte_tryget_map_lock | Try to increment a pte_refcount before |
-| | pte_offset_map_lock() |
-+---------------------+-------------------------------------------------+
-| pte_put | Decrement a pte_refcount |
-+---------------------+-------------------------------------------------+
-| pte_put_many | Sub a value to a pte_refcount |
-+---------------------+-------------------------------------------------+
-| pte_put_vmf | Decrement a pte_refcount in the page fault path |
-+---------------------+-------------------------------------------------+
++---------------------+------------------------------------------------------+
+| pte_ref_init | Initialize the pte_refcount and pmd |
++---------------------+------------------------------------------------------+
+| pte_to_pmd | Get the corresponding pmd |
++---------------------+------------------------------------------------------+
+| pte_update_pmd | Update the corresponding pmd |
++---------------------+------------------------------------------------------+
+| pte_get | Increment a pte_refcount |
++---------------------+------------------------------------------------------+
+| pte_get_many | Add a value to a pte_refcount |
++---------------------+------------------------------------------------------+
+| pte_get_unless_zero | Increment a pte_refcount unless it is 0 |
++---------------------+------------------------------------------------------+
+| pte_try_get | Try to increment a pte_refcount |
++---------------------+------------------------------------------------------+
+| pte_tryget_map | Try to increment a pte_refcount before |
+| | pte_offset_map() |
++---------------------+------------------------------------------------------+
+| pte_tryget_map_lock | Try to increment a pte_refcount before |
+| | pte_offset_map_lock() |
++---------------------+------------------------------------------------------+
+| __pte_put | Decrement a pte_refcount |
++---------------------+------------------------------------------------------+
+| __pte_put_many | Sub a value to a pte_refcount |
++---------------------+------------------------------------------------------+
+| pte_put | Decrement a pte_refcount(without tlb parameter) |
++---------------------+------------------------------------------------------+
+| pte_put_many | Sub a value to a pte_refcount(without tlb parameter) |
++---------------------+------------------------------------------------------+
+| pte_put_vmf | Decrement a pte_refcount in the page fault path |
++---------------------+------------------------------------------------------+
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ca5bfe83ec61..69ea13437947 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -233,7 +233,7 @@ config X86
select HAVE_PCI
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
- select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
+ select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT || FREE_USER_PTE
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
diff --git a/include/linux/pte_ref.h b/include/linux/pte_ref.h
index 8a26eaba83ef..dc3923bb38f6 100644
--- a/include/linux/pte_ref.h
+++ b/include/linux/pte_ref.h
@@ -22,7 +22,8 @@ enum pte_tryget_type pte_try_get(pmd_t *pmd);
bool pte_get_unless_zero(pmd_t *pmd);
#ifdef CONFIG_FREE_USER_PTE
-void free_user_pte_table(struct mm_struct *mm, pmd_t *pmdp, unsigned long addr);
+void free_user_pte_table(struct mmu_gather *tlb, struct mm_struct *mm,
+ pmd_t *pmd, unsigned long addr);
static inline void pte_ref_init(pgtable_t pte, pmd_t *pmd, int count)
{
@@ -48,14 +49,21 @@ static inline void pte_get_many(pmd_t *pmd, unsigned int nr)
atomic_add(nr, &pte->pte_refcount);
}
-static inline void pte_put_many(struct mm_struct *mm, pmd_t *pmd,
- unsigned long addr, unsigned int nr)
+static inline void __pte_put_many(struct mmu_gather *tlb, struct mm_struct *mm,
+ pmd_t *pmd, unsigned long addr,
+ unsigned int nr)
{
pgtable_t pte = pmd_pgtable(*pmd);
VM_BUG_ON(!PageTable(pte));
if (atomic_sub_and_test(nr, &pte->pte_refcount))
- free_user_pte_table(mm, pmd, addr & PMD_MASK);
+ free_user_pte_table(tlb, mm, pmd, addr & PMD_MASK);
+}
+
+static inline void __pte_put(struct mmu_gather *tlb, struct mm_struct *mm,
+ pmd_t *pmd, unsigned long addr)
+{
+ __pte_put_many(tlb, mm, pmd, addr, 1);
}
#else
static inline void pte_ref_init(pgtable_t pte, pmd_t *pmd, int count)
@@ -75,8 +83,14 @@ static inline void pte_get_many(pmd_t *pmd, unsigned int nr)
{
}
-static inline void pte_put_many(struct mm_struct *mm, pmd_t *pmd,
- unsigned long addr, unsigned int nr)
+static inline void __pte_put_many(struct mmu_gather *tlb, struct mm_struct *mm,
+ pmd_t *pmd, unsigned long addr,
+ unsigned int nr)
+{
+}
+
+static inline void __pte_put(struct mmu_gather *tlb, struct mm_struct *mm,
+ pmd_t *pmd, unsigned long addr)
{
}
#endif /* CONFIG_FREE_USER_PTE */
@@ -110,6 +124,12 @@ static inline pte_t *pte_tryget_map_lock(struct mm_struct *mm, pmd_t *pmd,
return pte_offset_map_lock(mm, pmd, address, ptlp);
}
+static inline void pte_put_many(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long addr, unsigned int nr)
+{
+ __pte_put_many(NULL, mm, pmd, addr, nr);
+}
+
/*
* pte_put - Decrement refcount for the PTE page table.
* @mm: the mm_struct of the target address space.
@@ -120,7 +140,7 @@ static inline pte_t *pte_tryget_map_lock(struct mm_struct *mm, pmd_t *pmd,
*/
static inline void pte_put(struct mm_struct *mm, pmd_t *pmd, unsigned long addr)
{
- pte_put_many(mm, pmd, addr, 1);
+ __pte_put(NULL, mm, pmd, addr);
}
#endif
diff --git a/mm/madvise.c b/mm/madvise.c
index 5cf2832abb98..b51254305bb2 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -477,7 +477,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(orig_pte, ptl);
- pte_put(vma->vm_mm, pmd, start);
+ __pte_put(tlb, vma->vm_mm, pmd, start);
if (pageout)
reclaim_pages(&page_list);
cond_resched();
@@ -710,7 +710,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(orig_pte, ptl);
if (nr_put)
- pte_put_many(mm, pmd, start, nr_put);
+ __pte_put_many(tlb, mm, pmd, start, nr_put);
cond_resched();
next:
return 0;
diff --git a/mm/memory.c b/mm/memory.c
index 4d1ede78d1b0..1bdae3b0f877 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1469,7 +1469,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
}
if (nr_put)
- pte_put_many(mm, pmd, start, nr_put);
+ __pte_put_many(tlb, mm, pmd, start, nr_put);
return addr;
}
@@ -1515,7 +1515,7 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
if (pte_try_get(pmd))
goto next;
next = zap_pte_range(tlb, vma, pmd, addr, next, details);
- pte_put(tlb->mm, pmd, addr);
+ __pte_put(tlb, tlb->mm, pmd, addr);
next:
cond_resched();
} while (pmd++, addr = next, addr != end);
diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c
index 1b9837419bf9..1bd9fa889421 100644
--- a/mm/mmu_gather.c
+++ b/mm/mmu_gather.c
@@ -134,42 +134,42 @@ static void __tlb_remove_table_free(struct mmu_table_batch *batch)
*
*/
-static void tlb_remove_table_smp_sync(void *arg)
+static void tlb_remove_table_rcu(struct rcu_head *head)
{
- /* Simply deliver the interrupt */
+ __tlb_remove_table_free(container_of(head, struct mmu_table_batch, rcu));
}
-static void tlb_remove_table_sync_one(void)
+static void tlb_remove_table_free(struct mmu_table_batch *batch)
{
- /*
- * This isn't an RCU grace period and hence the page-tables cannot be
- * assumed to be actually RCU-freed.
- *
- * It is however sufficient for software page-table walkers that rely on
- * IRQ disabling.
- */
- smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
+ call_rcu(&batch->rcu, tlb_remove_table_rcu);
}
-static void tlb_remove_table_rcu(struct rcu_head *head)
+static void tlb_remove_table_one_rcu(struct rcu_head *head)
{
- __tlb_remove_table_free(container_of(head, struct mmu_table_batch, rcu));
+ struct page *page = container_of(head, struct page, rcu_head);
+
+ __tlb_remove_table(page);
}
-static void tlb_remove_table_free(struct mmu_table_batch *batch)
+static void tlb_remove_table_one(void *table)
{
- call_rcu(&batch->rcu, tlb_remove_table_rcu);
+ pgtable_t page = (pgtable_t)table;
+
+ call_rcu(&page->rcu_head, tlb_remove_table_one_rcu);
}
#else /* !CONFIG_MMU_GATHER_RCU_TABLE_FREE */
-static void tlb_remove_table_sync_one(void) { }
-
static void tlb_remove_table_free(struct mmu_table_batch *batch)
{
__tlb_remove_table_free(batch);
}
+static void tlb_remove_table_one(void *table)
+{
+ __tlb_remove_table(table);
+}
+
#endif /* CONFIG_MMU_GATHER_RCU_TABLE_FREE */
/*
@@ -187,12 +187,6 @@ static inline void tlb_table_invalidate(struct mmu_gather *tlb)
}
}
-static void tlb_remove_table_one(void *table)
-{
- tlb_remove_table_sync_one();
- __tlb_remove_table(table);
-}
-
static void tlb_table_flush(struct mmu_gather *tlb)
{
struct mmu_table_batch **batch = &tlb->batch;
diff --git a/mm/pte_ref.c b/mm/pte_ref.c
index 728e61cea25e..f9650ad23c7c 100644
--- a/mm/pte_ref.c
+++ b/mm/pte_ref.c
@@ -8,6 +8,8 @@
#include <linux/pte_ref.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
+#include <asm/pgalloc.h>
+#include <asm/tlb.h>
#include <asm/tlbflush.h>
#ifdef CONFIG_FREE_USER_PTE
@@ -117,7 +119,8 @@ static void pte_free_rcu(struct rcu_head *rcu)
__free_page(page);
}
-void free_user_pte_table(struct mm_struct *mm, pmd_t *pmd, unsigned long addr)
+void free_user_pte_table(struct mmu_gather *tlb, struct mm_struct *mm,
+ pmd_t *pmd, unsigned long addr)
{
struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
spinlock_t *ptl;
@@ -125,10 +128,14 @@ void free_user_pte_table(struct mm_struct *mm, pmd_t *pmd, unsigned long addr)
ptl = pmd_lock(mm, pmd);
pmdval = pmdp_huge_get_and_clear(mm, addr, pmd);
- flush_tlb_range(&vma, addr, addr + PMD_SIZE);
+ if (!tlb)
+ flush_tlb_range(&vma, addr, addr + PMD_SIZE);
+ else
+ pte_free_tlb(tlb, pmd_pgtable(pmdval), addr);
spin_unlock(ptl);
pte_free_debug(pmdval);
mm_dec_nr_ptes(mm);
- call_rcu(&pmd_pgtable(pmdval)->rcu_head, pte_free_rcu);
+ if (!tlb)
+ call_rcu(&pmd_pgtable(pmdval)->rcu_head, pte_free_rcu);
}
--
2.11.0
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