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 fd825097cf048b59d8cc7486ae345e9cbec08b07..42b29b4ea9b6a28c3fa38bfaa4568fd7bf3ce8df 100644 (file)
--- a/arch/s390/configs/debug_defconfig
+++ b/arch/s390/configs/debug_defconfig
@@ -801,7 +801,6 @@ 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 537d92c41105bcec0c07d7da2eb5a9bef40787e7..fee18b63ed35cf3fcbae7e244c638af6f3a990a1 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>
@@ -1017,8 +1016,6 @@ 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 ad667dbc96f5cbb928e55678b092ed184dc3aaa7..300911d6575fdbb1745e9250a74c17b473465c84 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 04b055a805017fd5b15b8c60b900e25454b64e71..1ab6260fb164e7218aa2390e255fceb3f7de6a66 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -456,7 +456,6 @@ 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 78c351e35fec6361973c86c1a1337080af7a688a..4d8640b033192a5d2de92dad723fff4a3b73ae5e 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -856,7 +856,6 @@ 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 a185cc75ff52ae4d56fe0e92ab194e645e5ab9b3..dd9e1e98bdec9614d01c7f1c316b79376db0a060 100644 (file)
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -119,10 +119,6 @@ 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 bfe38869498d7cfa199cfc653d3b4b63f854b371..19cf5b6892ceba12c9f8acfa0a7910b4a2e726d4 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 da06a5553835b5e443555ee6b446e93abc2c3ffe..c4e6f5159bedb64878af7562f21eaef4e55b8153 100644 (file)
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -50,7 +50,6 @@
 #include <linux/pid.h>
 #include <linux/smp.h>
 #include <linux/mm.h>
-#include <linux/vmacache.h>
 #include <linux/rcupdate.h>
 #include <linux/irq.h>
 
@@ -282,17 +281,6 @@ 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 dcc58063f63215a3770f88d43185f2d9814a769c..3493117c8d35d3f32167f4c3d0265bd2d7046d27 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>
@@ -1056,7 +1055,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
        mm->mmap = NULL;
        mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
        mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
-       mm->vmacache_seqnum = 0;
        atomic_set(&mm->mm_users, 1);
        atomic_set(&mm->mm_count, 1);
        seqcount_init(&mm->write_protect_seq);
@@ -1512,9 +1510,6 @@ 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 24c6469948d535777d981d18063efc4dae8b87ce..3fb0d617fce30952462617a61ae7d84e4b04e502 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -802,16 +802,6 @@ 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 d6c0042e3aa0d1da49681ea436603a6110afd503..170056c0a7d1bddacf4759f0a89527a41294f6cc 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 a05a39ff8fe4f676a38b542dfc14c177369be5c8..440a0614d14ac18c98bd1002eb6317b09e47d782 100644 (file)
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -207,7 +207,7 @@ 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
@@ -235,7 +235,7 @@ 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 b0b7e327bf8bf031fa1ba0a2d6ff2ef24aa1c4a0..fddf38ca0589f258919f9ef6d99dcbe9d6dca48d 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>
@@ -655,9 +654,6 @@ 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);
 
@@ -877,8 +873,6 @@ 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) {
@@ -2142,19 +2136,10 @@ struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
                                             unsigned long start_addr,
                                             unsigned long end_addr)
 {
-       struct vm_area_struct *vma;
        MA_STATE(mas, &mm->mm_mt, start_addr, start_addr);
 
        mmap_assert_locked(mm);
-       /* Check the cache first. */
-       vma = vmacache_find(mm, start_addr);
-       if (likely(vma))
-               return vma;
-
-       vma = mas_find(&mas, end_addr - 1);
-       if (vma)
-               vmacache_update(mas.index, vma);
-       return vma;
+       return mas_find(&mas, end_addr - 1);
 }
 EXPORT_SYMBOL(find_vma_intersection);
 
@@ -2545,9 +2530,6 @@ 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
@@ -2928,7 +2910,6 @@ 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 c5ded0f92a528a4bada9bc26809cefbb28f0e90a..11ae550834cde4395b3a3b955ab1182f0022e026 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>
@@ -583,23 +582,12 @@ 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);
@@ -611,7 +599,7 @@ 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);
 }
 
 /*
@@ -633,20 +621,9 @@ static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
  */
 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;
-
-       vma = mas_walk(&mas);
-
-       if (vma)
-               vmacache_update(addr, vma);
-
-       return vma;
+       return mas_walk(&mas);
 }
 EXPORT_SYMBOL(find_vma);
 
@@ -680,11 +657,6 @@ 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;
-
        vma = mas_walk(&mas);
        if (!vma)
                return NULL;
@@ -693,7 +665,6 @@ 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 d701c335628c86c799bb33c7dba2f42f1c7b6fed..09045aa69f1359e8595cc3d997ebaffa0fef2555 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1375,10 +1375,6 @@ 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",