mm: Remove vmacache

By using the maple tree and the maple tree state, the vmacache is no
longer beneficial and is complicating the VMA code.  Remove the vmacache
to reduce the work in keeping it up to date and code complexity.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

diff --git a/arch/s390/configs/debug_defconfig b/arch/s390/configs/debug_defconfig
index 86afcc6b56bf745331f0669ce99a0d1c5ed2c477..f754bf7112619ccf0598c2b829236bdcd13d5dca 100644 (file)
--- a/arch/s390/configs/debug_defconfig
+++ b/arch/s390/configs/debug_defconfig
@@ -791,7 +791,6 @@ CONFIG_SLUB_DEBUG_ON=y
 CONFIG_SLUB_STATS=y
 CONFIG_DEBUG_STACK_USAGE=y
 CONFIG_DEBUG_VM=y
-CONFIG_DEBUG_VM_VMACACHE=y
 CONFIG_DEBUG_VM_PGFLAGS=y
 CONFIG_DEBUG_MEMORY_INIT=y
 CONFIG_MEMORY_NOTIFIER_ERROR_INJECT=m

diff --git a/fs/exec.c b/fs/exec.c
index 18594f11c31fe12e28e80349e7fb1211613e681c..3d3f7d46137cfdc7ceb01ffa2fbb4adffb2531b7 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -28,7 +28,6 @@
 #include <linux/file.h>
 #include <linux/fdtable.h>
 #include <linux/mm.h>
-#include <linux/vmacache.h>
 #include <linux/stat.h>
 #include <linux/fcntl.h>
 #include <linux/swap.h>
@@ -1020,8 +1019,6 @@ static int exec_mmap(struct mm_struct *mm)
        activate_mm(active_mm, mm);
        if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
                local_irq_enable();
-       tsk->mm->vmacache_seqnum = 0;
-       vmacache_flush(tsk);
        task_unlock(tsk);
        if (old_mm) {
                mmap_read_unlock(old_mm);

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index fc9784544b241dec403ca82d3e8b7e8b19b4cd03..503e1355cf6e6d3f4420d1d1e6ac55c31e8d275f 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/pagewalk.h>
-#include <linux/vmacache.h>
 #include <linux/hugetlb.h>
 #include <linux/huge_mm.h>
 #include <linux/mount.h>

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 41551bfa6ce09cc6c3b14a0671dab4466a672f78..304692ada0241552c8ae7b8a1f488a895409f822 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -380,7 +380,6 @@ struct mm_struct {
        struct {
                struct vm_area_struct *mmap;            /* list of VMAs */
                struct maple_tree mm_mt;
-               u64 vmacache_seqnum;                   /* per-thread vmacache */
 #ifdef CONFIG_MMU
                unsigned long (*get_unmapped_area) (struct file *filp,
                                unsigned long addr, unsigned long len,

diff --git a/include/linux/mm_types_task.h b/include/linux/mm_types_task.h
index c1bc6731125cbbeb99b2bbe0d4757fad6bf5031f..33c9fa4d4f66aaee5ddfa6d9f0918cee398834b0 100644 (file)
--- a/include/linux/mm_types_task.h
+++ b/include/linux/mm_types_task.h
@@ -31,11 +31,6 @@
 #define VMACACHE_SIZE (1U << VMACACHE_BITS)
 #define VMACACHE_MASK (VMACACHE_SIZE - 1)
 
-struct vmacache {
-       u64 seqnum;
-       struct vm_area_struct *vmas[VMACACHE_SIZE];
-};
-
 /*
  * When updating this, please also update struct resident_page_types[] in
  * kernel/fork.c

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8d5264b18cb66366aa5a8d8f7e6ce11145a17537..e85fcd3ef86a97db145ae6be761a7e8ae49093d8 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -772,7 +772,6 @@ struct task_struct {
        struct mm_struct                *active_mm;
 
        /* Per-thread vma caching: */
-       struct vmacache                 vmacache;
 
 #ifdef SPLIT_RSS_COUNTING
        struct task_rss_stat            rss_stat;

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index ae0dd1948c2b0521dd8461f5d8828b7f6d25f7ed..cd3ff075470b96964c0d99025c3bafef8b51c1c4 100644 (file)
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -117,10 +117,6 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
                NR_TLB_LOCAL_FLUSH_ALL,
                NR_TLB_LOCAL_FLUSH_ONE,
 #endif /* CONFIG_DEBUG_TLBFLUSH */
-#ifdef CONFIG_DEBUG_VM_VMACACHE
-               VMACACHE_FIND_CALLS,
-               VMACACHE_FIND_HITS,
-#endif
 #ifdef CONFIG_SWAP
                SWAP_RA,
                SWAP_RA_HIT,

diff --git a/include/linux/vmacache.h b/include/linux/vmacache.h
deleted file mode 100644 (file)
index 6fce268..0000000
--- a/include/linux/vmacache.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __LINUX_VMACACHE_H
-#define __LINUX_VMACACHE_H
-
-#include <linux/sched.h>
-#include <linux/mm.h>
-
-static inline void vmacache_flush(struct task_struct *tsk)
-{
-       memset(tsk->vmacache.vmas, 0, sizeof(tsk->vmacache.vmas));
-}
-
-extern void vmacache_update(unsigned long addr, struct vm_area_struct *newvma);
-extern struct vm_area_struct *vmacache_find(struct mm_struct *mm,
-                                                   unsigned long addr);
-
-#ifndef CONFIG_MMU
-extern struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm,
-                                                 unsigned long start,
-                                                 unsigned long end);
-#endif
-
-static inline void vmacache_invalidate(struct mm_struct *mm)
-{
-       mm->vmacache_seqnum++;
-}
-
-#endif /* __LINUX_VMACACHE_H */

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 3299cd69e4ca38d0e39fba7c0284b6862f25c572..0517f3b123eaae4e51782d929baab0f394bc328d 100644 (file)
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -125,12 +125,6 @@ static inline void vm_events_fold_cpu(int cpu)
 #define count_vm_tlb_events(x, y) do { (void)(y); } while (0)
 #endif
 
-#ifdef CONFIG_DEBUG_VM_VMACACHE
-#define count_vm_vmacache_event(x) count_vm_event(x)
-#else
-#define count_vm_vmacache_event(x) do {} while (0)
-#endif
-
 #define __count_zid_vm_events(item, zid, delta) \
        __count_vm_events(item##_NORMAL - ZONE_NORMAL + zid, delta)
 

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 4708aec492df9e54145bfc4084adeb4b21639f5e..1bd0bb76ed2cebad5a27ab32745f4fde67d511f5 100644 (file)
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -53,7 +53,6 @@
 #include <linux/pid.h>
 #include <linux/smp.h>
 #include <linux/mm.h>
-#include <linux/vmacache.h>
 #include <linux/rcupdate.h>
 #include <linux/irq.h>
 
@@ -285,17 +284,6 @@ static void kgdb_flush_swbreak_addr(unsigned long addr)
        if (!CACHE_FLUSH_IS_SAFE)
                return;
 
-       if (current->mm) {
-               int i;
-
-               for (i = 0; i < VMACACHE_SIZE; i++) {
-                       if (!current->vmacache.vmas[i])
-                               continue;
-                       flush_cache_range(current->vmacache.vmas[i],
-                                         addr, addr + BREAK_INSTR_SIZE);
-               }
-       }
-
        /* Force flush instruction cache if it was outside the mm */
        flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
 }

diff --git a/kernel/fork.c b/kernel/fork.c
index fc5937b52a6bac3689ee9f8d63735c7cba016eee..a3504820c5427a85399272bdf6f009cfcbdc1180 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -42,7 +42,6 @@
 #include <linux/mmu_notifier.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
-#include <linux/vmacache.h>
 #include <linux/nsproxy.h>
 #include <linux/capability.h>
 #include <linux/cpu.h>
@@ -1027,7 +1026,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
 {
        mm->mmap = NULL;
        mt_init_flags(&mm->mm_mt, MAPLE_ALLOC_RANGE);
-       mm->vmacache_seqnum = 0;
        atomic_set(&mm->mm_users, 1);
        atomic_set(&mm->mm_count, 1);
        seqcount_init(&mm->write_protect_seq);
@@ -1425,9 +1423,6 @@ static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
        if (!oldmm)
                return 0;
 
-       /* initialize the new vmacache entries */
-       vmacache_flush(tsk);
-
        if (clone_flags & CLONE_VM) {
                mmget(oldmm);
                mm = oldmm;

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index aff641743bd00e50a1e40a25e2cb2974e39c8648..49d9476d6a2033f52e7445f21ca541348071f1b1 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -789,16 +789,6 @@ config DEBUG_VM
 
          If unsure, say N.
 
-config DEBUG_VM_VMACACHE
-       bool "Debug VMA caching"
-       depends on DEBUG_VM
-       help
-         Enable this to turn on VMA caching debug information. Doing so
-         can cause significant overhead, so only enable it in non-production
-         environments.
-
-         If unsure, say N.
-
 config DEBUG_VM_RB
        bool "Debug VM red-black trees"
        depends on DEBUG_VM

diff --git a/mm/Makefile b/mm/Makefile
index a9ad6122d468f4ed5e1596622fadb9d689a119de..a061cf7fd591f056c96985375e751de98c32f9a6 100644 (file)
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -50,7 +50,7 @@ obj-y                 := filemap.o mempool.o oom_kill.o fadvise.o \
                           readahead.o swap.o truncate.o vmscan.o shmem.o \
                           util.o mmzone.o vmstat.o backing-dev.o \
                           mm_init.o percpu.o slab_common.o \
-                          compaction.o vmacache.o \
+                          compaction.o \
                           interval_tree.o list_lru.o workingset.o \
                           debug.o gup.o mmap_lock.o $(mmu-y)
 

diff --git a/mm/debug.c b/mm/debug.c
index 0bdda8407f71e7ae4089cf831199372da3b59f12..f382d319722a5ce726254e1b989b8f30506161d7 100644 (file)
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -214,7 +214,7 @@ EXPORT_SYMBOL(dump_vma);
 
 void dump_mm(const struct mm_struct *mm)
 {
-       pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
+       pr_emerg("mm %px mmap %px task_size %lu\n"
 #ifdef CONFIG_MMU
                "get_unmapped_area %px\n"
 #endif
@@ -242,7 +242,7 @@ void dump_mm(const struct mm_struct *mm)
                "tlb_flush_pending %d\n"
                "def_flags: %#lx(%pGv)\n",
 
-               mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
+               mm, mm->mmap, mm->task_size,
 #ifdef CONFIG_MMU
                mm->get_unmapped_area,
 #endif

diff --git a/mm/mmap.c b/mm/mmap.c
index 0a2f18ea194c44de3d8f35eb2fe6d31cf887d9a6..70cbc39e0d425fbc0bebb5fdc9a145f090efdc2f 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -13,7 +13,6 @@
 #include <linux/slab.h>
 #include <linux/backing-dev.h>
 #include <linux/mm.h>
-#include <linux/vmacache.h>
 #include <linux/shm.h>
 #include <linux/mman.h>
 #include <linux/pagemap.h>
@@ -688,9 +687,6 @@ inline int vma_expand(struct ma_state *mas, struct vm_area_struct *vma,
                /* Remove from mm linked list - also updates highest_vm_end */
                __vma_unlink_list(mm, next);
 
-               /* Kill the cache */
-               vmacache_invalidate(mm);
-
                if (file)
                        __remove_shared_vm_struct(next, file, mapping);
 
@@ -904,8 +900,6 @@ again:
 
        if (remove_next) {
                __vma_unlink_list(mm, next);
-               /* Kill the cache */
-               vmacache_invalidate(mm);
                if (file)
                        __remove_shared_vm_struct(next, file, mapping);
        } else if (insert) {
@@ -2188,16 +2182,9 @@ struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
        struct vm_area_struct *vma;
        MA_STATE(mas, &mm->mm_mt, start_addr, start_addr);
 
-       /* Check the cache first. */
-       vma = vmacache_find(mm, start_addr);
-       if (likely(vma))
-               return vma;
-
        rcu_read_lock();
        vma = mas_find(&mas, end_addr - 1);
        rcu_read_unlock();
-       if (vma)
-               vmacache_update(mas.index, vma);
 
        return vma;
 }
@@ -2590,9 +2577,6 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
                mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
        tail_vma->vm_next = NULL;
 
-       /* Kill the cache */
-       vmacache_invalidate(mm);
-
        /*
         * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or
         * VM_GROWSUP VMA. Such VMAs can change their size under
@@ -2975,7 +2959,6 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
        if (vma_mas_remove(&unmap, mas))
                goto mas_store_fail;
 
-       vmacache_invalidate(vma->vm_mm);
        if (vma->anon_vma) {
                anon_vma_interval_tree_post_update_vma(vma);
                anon_vma_unlock_write(vma->anon_vma);

diff --git a/mm/nommu.c b/mm/nommu.c
index c410f99203fb4e7b8ecb3c0220da99413899471a..0eea24df1bd58472c6f992d86ff7d02ad9189ecb 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -19,7 +19,6 @@
 #include <linux/export.h>
 #include <linux/mm.h>
 #include <linux/sched/mm.h>
-#include <linux/vmacache.h>
 #include <linux/mman.h>
 #include <linux/swap.h>
 #include <linux/file.h>
@@ -601,22 +600,12 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
  */
 static void delete_vma_from_mm(struct vm_area_struct *vma)
 {
-       int i;
-       struct address_space *mapping;
-       struct mm_struct *mm = vma->vm_mm;
-       struct task_struct *curr = current;
        MA_STATE(mas, &vma->vm_mm->mm_mt, 0, 0);
 
-       mm->map_count--;
-       for (i = 0; i < VMACACHE_SIZE; i++) {
-               /* if the vma is cached, invalidate the entire cache */
-               if (curr->vmacache.vmas[i] == vma) {
-                       vmacache_invalidate(mm);
-                       break;
-               }
-       }
+       vma->vm_mm->map_count--;
        /* remove the VMA from the mapping */
        if (vma->vm_file) {
+               struct address_space *mapping;
                mapping = vma->vm_file->f_mapping;
 
                i_mmap_lock_write(mapping);
@@ -628,7 +617,7 @@ static void delete_vma_from_mm(struct vm_area_struct *vma)
 
        /* remove from the MM's tree and list */
        vma_mas_remove(vma, &mas);
-       __vma_unlink_list(mm, vma);
+       __vma_unlink_list(vma->vm_mm, vma);
 }
 
 /*
@@ -653,18 +642,10 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
        struct vm_area_struct *vma;
        MA_STATE(mas, &mm->mm_mt, addr, addr);
 
-       /* check the cache first */
-       vma = vmacache_find(mm, addr);
-       if (likely(vma))
-               return vma;
-
        rcu_read_lock();
        vma = mas_walk(&mas);
        rcu_read_unlock();
 
-       if (vma)
-               vmacache_update(addr, vma);
-
        return vma;
 }
 EXPORT_SYMBOL(find_vma);
@@ -699,11 +680,6 @@ static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
        unsigned long end = addr + len;
        MA_STATE(mas, &mm->mm_mt, addr, addr);
 
-       /* check the cache first */
-       vma = vmacache_find_exact(mm, addr, end);
-       if (vma)
-               return vma;
-
        rcu_read_lock();
        vma = mas_walk(&mas);
        rcu_read_unlock();
@@ -714,7 +690,6 @@ static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
        if (vma->vm_end != end)
                return NULL;
 
-       vmacache_update(addr, vma);
        return vma;
 }
 

diff --git a/mm/vmacache.c b/mm/vmacache.c
deleted file mode 100644 (file)
index 01a6e66..0000000
--- a/mm/vmacache.c
+++ /dev/null
@@ -1,117 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright (C) 2014 Davidlohr Bueso.
- */
-#include <linux/sched/signal.h>
-#include <linux/sched/task.h>
-#include <linux/mm.h>
-#include <linux/vmacache.h>
-
-/*
- * Hash based on the pmd of addr if configured with MMU, which provides a good
- * hit rate for workloads with spatial locality.  Otherwise, use pages.
- */
-#ifdef CONFIG_MMU
-#define VMACACHE_SHIFT PMD_SHIFT
-#else
-#define VMACACHE_SHIFT PAGE_SHIFT
-#endif
-#define VMACACHE_HASH(addr) ((addr >> VMACACHE_SHIFT) & VMACACHE_MASK)
-
-/*
- * This task may be accessing a foreign mm via (for example)
- * get_user_pages()->find_vma().  The vmacache is task-local and this
- * task's vmacache pertains to a different mm (ie, its own).  There is
- * nothing we can do here.
- *
- * Also handle the case where a kernel thread has adopted this mm via
- * kthread_use_mm(). That kernel thread's vmacache is not applicable to this mm.
- */
-static inline bool vmacache_valid_mm(struct mm_struct *mm)
-{
-       return current->mm == mm && !(current->flags & PF_KTHREAD);
-}
-
-void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)
-{
-       if (vmacache_valid_mm(newvma->vm_mm))
-               current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma;
-}
-
-static bool vmacache_valid(struct mm_struct *mm)
-{
-       struct task_struct *curr;
-
-       if (!vmacache_valid_mm(mm))
-               return false;
-
-       curr = current;
-       if (mm->vmacache_seqnum != curr->vmacache.seqnum) {
-               /*
-                * First attempt will always be invalid, initialize
-                * the new cache for this task here.
-                */
-               curr->vmacache.seqnum = mm->vmacache_seqnum;
-               vmacache_flush(curr);
-               return false;
-       }
-       return true;
-}
-
-struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr)
-{
-       int idx = VMACACHE_HASH(addr);
-       int i;
-
-       count_vm_vmacache_event(VMACACHE_FIND_CALLS);
-
-       if (!vmacache_valid(mm))
-               return NULL;
-
-       for (i = 0; i < VMACACHE_SIZE; i++) {
-               struct vm_area_struct *vma = current->vmacache.vmas[idx];
-
-               if (vma) {
-#ifdef CONFIG_DEBUG_VM_VMACACHE
-                       if (WARN_ON_ONCE(vma->vm_mm != mm))
-                               break;
-#endif
-                       if (vma->vm_start <= addr && vma->vm_end > addr) {
-                               count_vm_vmacache_event(VMACACHE_FIND_HITS);
-                               return vma;
-                       }
-               }
-               if (++idx == VMACACHE_SIZE)
-                       idx = 0;
-       }
-
-       return NULL;
-}
-
-#ifndef CONFIG_MMU
-struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm,
-                                          unsigned long start,
-                                          unsigned long end)
-{
-       int idx = VMACACHE_HASH(start);
-       int i;
-
-       count_vm_vmacache_event(VMACACHE_FIND_CALLS);
-
-       if (!vmacache_valid(mm))
-               return NULL;
-
-       for (i = 0; i < VMACACHE_SIZE; i++) {
-               struct vm_area_struct *vma = current->vmacache.vmas[idx];
-
-               if (vma && vma->vm_start == start && vma->vm_end == end) {
-                       count_vm_vmacache_event(VMACACHE_FIND_HITS);
-                       return vma;
-               }
-               if (++idx == VMACACHE_SIZE)
-                       idx = 0;
-       }
-
-       return NULL;
-}
-#endif

diff --git a/mm/vmstat.c b/mm/vmstat.c
index cccee36b289c25b38b91fc3ddada12b6267c6061..37bf2fef2cee8069f6f8ebefa3c3161f924e0ed5 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1361,10 +1361,6 @@ const char * const vmstat_text[] = {
        "nr_tlb_local_flush_one",
 #endif /* CONFIG_DEBUG_TLBFLUSH */
 
-#ifdef CONFIG_DEBUG_VM_VMACACHE
-       "vmacache_find_calls",
-       "vmacache_find_hits",
-#endif
 #ifdef CONFIG_SWAP
        "swap_ra",
        "swap_ra_hit",