From f0dd152c49e2be4f716a16211d41fac2b15a5224 Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Mon, 16 Nov 2020 14:50:20 -0500 Subject: [PATCH] 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 --- arch/s390/configs/debug_defconfig | 1 - fs/exec.c | 3 - fs/proc/task_mmu.c | 1 - include/linux/mm_types.h | 1 - include/linux/mm_types_task.h | 5 -- include/linux/sched.h | 1 - include/linux/vm_event_item.h | 4 - include/linux/vmacache.h | 28 ------- include/linux/vmstat.h | 6 -- kernel/debug/debug_core.c | 12 --- kernel/fork.c | 5 -- lib/Kconfig.debug | 10 --- mm/Makefile | 2 +- mm/debug.c | 4 +- mm/mmap.c | 17 ----- mm/nommu.c | 31 +------- mm/vmacache.c | 117 ------------------------------ mm/vmstat.c | 4 - 18 files changed, 6 insertions(+), 246 deletions(-) delete mode 100644 include/linux/vmacache.h delete mode 100644 mm/vmacache.c diff --git a/arch/s390/configs/debug_defconfig b/arch/s390/configs/debug_defconfig index 86afcc6b56bf..f754bf711261 100644 --- 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 18594f11c31f..3d3f7d46137c 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -28,7 +28,6 @@ #include #include #include -#include #include #include #include @@ -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 fc9784544b24..503e1355cf6e 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1,6 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 #include -#include #include #include #include diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 41551bfa6ce0..304692ada024 100644 --- 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 c1bc6731125c..33c9fa4d4f66 100644 --- 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 8d5264b18cb6..e85fcd3ef86a 100644 --- 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 ae0dd1948c2b..cd3ff075470b 100644 --- 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 index 6fce268a4588..000000000000 --- 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 -#include - -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 3299cd69e4ca..0517f3b123ea 100644 --- 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 4708aec492df..1bd0bb76ed2c 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -53,7 +53,6 @@ #include #include #include -#include #include #include @@ -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 fc5937b52a6b..a3504820c542 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -42,7 +42,6 @@ #include #include #include -#include #include #include #include @@ -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 aff641743bd0..49d9476d6a20 100644 --- 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 a9ad6122d468..a061cf7fd591 100644 --- 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 0bdda8407f71..f382d319722a 100644 --- 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 0a2f18ea194c..70cbc39e0d42 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -13,7 +13,6 @@ #include #include #include -#include #include #include #include @@ -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 c410f99203fb..0eea24df1bd5 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -19,7 +19,6 @@ #include #include #include -#include #include #include #include @@ -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 index 01a6e6688ec1..000000000000 --- a/mm/vmacache.c +++ /dev/null @@ -1,117 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * Copyright (C) 2014 Davidlohr Bueso. - */ -#include -#include -#include -#include - -/* - * 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 cccee36b289c..37bf2fef2cee 100644 --- 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", -- 2.50.1