[v5,1/6] mm/page_idle: Add per-pid idle page tracking using virtual index

Message ID	20190807171559.182301-1-joel@joelfernandes.org (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-fsdevel-owner@kernel.org> From: "Joel Fernandes (Google)" <joel@joelfernandes.org> To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>, Alexey Dobriyan <adobriyan@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Borislav Petkov <bp@alien8.de>, Brendan Gregg <bgregg@netflix.com>, Catalin Marinas <catalin.marinas@arm.com>, Christian Hansen <chansen3@cisco.com>, dancol@google.com, fmayer@google.com, "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>, joelaf@google.com, Jonathan Corbet <corbet@lwn.net>, Kees Cook <keescook@chromium.org>, kernel-team@android.com, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko <mhocko@suse.com>, Mike Rapoport <rppt@linux.ibm.com>, minchan@kernel.org, namhyung@google.com, paulmck@linux.ibm.com, Robin Murphy <robin.murphy@arm.com>, Roman Gushchin <guro@fb.com>, Stephen Rothwell <sfr@canb.auug.org.au>, surenb@google.com, Thomas Gleixner <tglx@linutronix.de>, tkjos@google.com, Vladimir Davydov <vdavydov.dev@gmail.com>, Vlastimil Babka <vbabka@suse.cz>, Will Deacon <will@kernel.org> Subject: [PATCH v5 1/6] mm/page_idle: Add per-pid idle page tracking using virtual index Date: Wed, 7 Aug 2019 13:15:54 -0400 Message-Id: <20190807171559.182301-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk
Series	[v5,1/6] mm/page_idle: Add per-pid idle page tracking using virtual index \| expand [v5,1/6] mm/page_idle: Add per-pid idle page tracking using virtual index [v5,2/6] mm/page_idle: Add support for handling swapped PG_Idle pages [v5,3/6,RFC] x86: Add support for idle bit in swap PTE [v5,4/6,RFC] arm64: Add support for idle bit in swap PTE [v5,5/6] page_idle: Drain all LRU pagevec before idle tracking [v5,6/6] doc: Update documentation for page_idle virtual address indexing

diff --git a/fs/proc/base.c b/fs/proc/base.c index ebea9501afb8..fd2f74bd4e35 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3039,6 +3039,9 @@ static const struct pid_entry tgid_base_stuff[] = { REG("smaps", S_IRUGO, proc_pid_smaps_operations), REG("smaps_rollup", S_IRUGO, proc_pid_smaps_rollup_operations), REG("pagemap", S_IRUSR, proc_pagemap_operations), +#ifdef CONFIG_IDLE_PAGE_TRACKING + REG("page_idle", S_IRUSR|S_IWUSR, proc_page_idle_operations), +#endif #endif #ifdef CONFIG_SECURITY DIR("attr", S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations), diff --git a/fs/proc/internal.h b/fs/proc/internal.h index cd0c8d5ce9a1..bc9371880c63 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -293,6 +293,7 @@ extern const struct file_operations proc_pid_smaps_operations; extern const struct file_operations proc_pid_smaps_rollup_operations; extern const struct file_operations proc_clear_refs_operations; extern const struct file_operations proc_pagemap_operations; +extern const struct file_operations proc_page_idle_operations; extern unsigned long task_vsize(struct mm_struct *); extern unsigned long task_statm(struct mm_struct *, diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 582c5e680176..192ffc4e24d7 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1650,6 +1650,48 @@ const struct file_operations proc_pagemap_operations = { .open = pagemap_open, .release = pagemap_release, }; + +#ifdef CONFIG_IDLE_PAGE_TRACKING +static ssize_t proc_page_idle_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + return page_idle_proc_read(file, buf, count, ppos); +} + +static ssize_t proc_page_idle_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + return page_idle_proc_write(file, (char __user *)buf, count, ppos); +} + +static int proc_page_idle_open(struct inode *inode, struct file *file) +{ + struct mm_struct *mm; + + mm = proc_mem_open(inode, PTRACE_MODE_READ); + if (IS_ERR(mm)) + return PTR_ERR(mm); + file->private_data = mm; + return 0; +} + +static int proc_page_idle_release(struct inode *inode, struct file *file) +{ + struct mm_struct *mm = file->private_data; + + mmdrop(mm); + return 0; +} + +const struct file_operations proc_page_idle_operations = { + .llseek = mem_lseek, /* borrow this */ + .read = proc_page_idle_read, + .write = proc_page_idle_write, + .open = proc_page_idle_open, + .release = proc_page_idle_release, +}; +#endif /* CONFIG_IDLE_PAGE_TRACKING */ + #endif /* CONFIG_PROC_PAGE_MONITOR */ #ifdef CONFIG_NUMA diff --git a/include/linux/page_idle.h b/include/linux/page_idle.h index 1e894d34bdce..a765a6d14e1a 100644 --- a/include/linux/page_idle.h +++ b/include/linux/page_idle.h @@ -106,6 +106,10 @@ static inline void clear_page_idle(struct page *page) } #endif /* CONFIG_64BIT */ +ssize_t page_idle_proc_write(struct file *file, + char __user *buf, size_t count, loff_t *ppos); +ssize_t page_idle_proc_read(struct file *file, + char __user *buf, size_t count, loff_t *ppos); #else /* !CONFIG_IDLE_PAGE_TRACKING */ static inline bool page_is_young(struct page *page) diff --git a/mm/page_idle.c b/mm/page_idle.c index 295512465065..9de4f4c67a8c 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -5,17 +5,22 @@ #include <linux/sysfs.h> #include <linux/kobject.h> #include <linux/mm.h> -#include <linux/mmzone.h> -#include <linux/pagemap.h> -#include <linux/rmap.h> #include <linux/mmu_notifier.h> +#include <linux/mmzone.h> #include <linux/page_ext.h> #include <linux/page_idle.h> +#include <linux/pagemap.h> +#include <linux/rmap.h> +#include <linux/sched/mm.h> +#include <linux/swap.h> +#include <linux/swapops.h> #define BITMAP_CHUNK_SIZE sizeof(u64) #define BITMAP_CHUNK_BITS (BITMAP_CHUNK_SIZE * BITS_PER_BYTE) /* + * Get a reference to a page for idle tracking purposes, with additional checks. + * * Idle page tracking only considers user memory pages, for other types of * pages the idle flag is always unset and an attempt to set it is silently * ignored. @@ -25,18 +30,13 @@ * page tracking. With such an indicator of user pages we can skip isolated * pages, but since there are not usually many of them, it will hardly affect * the overall result. - * - * This function tries to get a user memory page by pfn as described above. */ -static struct page *page_idle_get_page(unsigned long pfn) +static struct page *page_idle_get_page(struct page *page_in) { struct page *page; pg_data_t *pgdat; - if (!pfn_valid(pfn)) - return NULL; - - page = pfn_to_page(pfn); + page = page_in; if (!page || !PageLRU(page) || !get_page_unless_zero(page)) return NULL; @@ -51,6 +51,18 @@ static struct page *page_idle_get_page(unsigned long pfn) return page; } +/* + * This function tries to get a user memory page by pfn as described above. + */ +static struct page *page_idle_get_page_pfn(unsigned long pfn) +{ + + if (!pfn_valid(pfn)) + return NULL; + + return page_idle_get_page(pfn_to_page(pfn)); +} + static bool page_idle_clear_pte_refs_one(struct page *page, struct vm_area_struct *vma, unsigned long addr, void *arg) @@ -118,6 +130,47 @@ static void page_idle_clear_pte_refs(struct page *page) unlock_page(page); } +/* Helper to get the start and end frame given a pos and count */ +static int page_idle_get_frames(loff_t pos, size_t count, struct mm_struct *mm, + unsigned long *start, unsigned long *end) +{ + unsigned long max_frame; + + /* If an mm is not given, assume we want physical frames */ + max_frame = mm ? (mm->task_size >> PAGE_SHIFT) : max_pfn; + + if (pos % BITMAP_CHUNK_SIZE || count % BITMAP_CHUNK_SIZE) + return -EINVAL; + + *start = pos * BITS_PER_BYTE; + if (*start >= max_frame) + return -ENXIO; + + *end = *start + count * BITS_PER_BYTE; + if (*end > max_frame) + *end = max_frame; + return 0; +} + +static bool page_idle_pte_check(struct page *page) +{ + if (!page) + return false; + + if (page_is_idle(page)) { + /* + * The page might have been referenced via a + * pte, in which case it is not idle. Clear + * refs and recheck. + */ + page_idle_clear_pte_refs(page); + if (page_is_idle(page)) + return true; + } + + return false; +} + static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj, struct bin_attribute *attr, char *buf, loff_t pos, size_t count) @@ -125,35 +178,21 @@ static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj, u64 *out = (u64 *)buf; struct page *page; unsigned long pfn, end_pfn; - int bit; + int bit, ret; - if (pos % BITMAP_CHUNK_SIZE || count % BITMAP_CHUNK_SIZE) - return -EINVAL; - - pfn = pos * BITS_PER_BYTE; - if (pfn >= max_pfn) - return 0; - - end_pfn = pfn + count * BITS_PER_BYTE; - if (end_pfn > max_pfn) - end_pfn = max_pfn; + ret = page_idle_get_frames(pos, count, NULL, &pfn, &end_pfn); + if (ret == -ENXIO) + return 0; /* Reads beyond max_pfn do nothing */ + else if (ret) + return ret; for (; pfn < end_pfn; pfn++) { bit = pfn % BITMAP_CHUNK_BITS; if (!bit) *out = 0ULL; - page = page_idle_get_page(pfn); - if (page) { - if (page_is_idle(page)) { - /* - * The page might have been referenced via a - * pte, in which case it is not idle. Clear - * refs and recheck. - */ - page_idle_clear_pte_refs(page); - if (page_is_idle(page)) - *out |= 1ULL << bit; - } + page = page_idle_get_page_pfn(pfn); + if (page && page_idle_pte_check(page)) { + *out |= 1ULL << bit; put_page(page); } if (bit == BITMAP_CHUNK_BITS - 1) @@ -170,23 +209,16 @@ static ssize_t page_idle_bitmap_write(struct file *file, struct kobject *kobj, const u64 *in = (u64 *)buf; struct page *page; unsigned long pfn, end_pfn; - int bit; + int bit, ret; - if (pos % BITMAP_CHUNK_SIZE || count % BITMAP_CHUNK_SIZE) - return -EINVAL; - - pfn = pos * BITS_PER_BYTE; - if (pfn >= max_pfn) - return -ENXIO; - - end_pfn = pfn + count * BITS_PER_BYTE; - if (end_pfn > max_pfn) - end_pfn = max_pfn; + ret = page_idle_get_frames(pos, count, NULL, &pfn, &end_pfn); + if (ret) + return ret; for (; pfn < end_pfn; pfn++) { bit = pfn % BITMAP_CHUNK_BITS; if ((*in >> bit) & 1) { - page = page_idle_get_page(pfn); + page = page_idle_get_page_pfn(pfn); if (page) { page_idle_clear_pte_refs(page); set_page_idle(page); @@ -224,6 +256,221 @@ struct page_ext_operations page_idle_ops = { }; #endif +/* page_idle tracking for /proc/<pid>/page_idle */ + +struct page_node { + struct page *page; + unsigned long addr; + struct list_head list; +}; + +struct page_idle_proc_priv { + unsigned long start_addr; + char *buffer; + int write; + + /* Pre-allocate and provide nodes to pte_page_idle_proc_add() */ + struct page_node *page_nodes; + int cur_page_node; + struct list_head *idle_page_list; +}; + +/* + * Add page to list to be set as idle later. + */ +static void pte_page_idle_proc_add(struct page *page, + unsigned long addr, struct mm_walk *walk) +{ + struct page *page_get = NULL; + struct page_node *pn; + int bit; + unsigned long frames; + struct page_idle_proc_priv *priv = walk->private; + u64 *chunk = (u64 *)priv->buffer; + + if (priv->write) { + VM_BUG_ON(!page); + + /* Find whether this page was asked to be marked */ + frames = (addr - priv->start_addr) >> PAGE_SHIFT; + bit = frames % BITMAP_CHUNK_BITS; + chunk = &chunk[frames / BITMAP_CHUNK_BITS]; + if (((*chunk >> bit) & 1) == 0) + return; + } + + if (page) { + page_get = page_idle_get_page(page); + if (!page_get) + return; + } + + /* + * For all other pages, add it to a list since we have to walk rmap, + * which acquires ptlock, and we cannot walk rmap right now. + */ + pn = &(priv->page_nodes[priv->cur_page_node++]); + pn->page = page_get; + pn->addr = addr; + list_add(&pn->list, priv->idle_page_list); +} + +static int pte_page_idle_proc_range(pmd_t *pmd, unsigned long addr, + unsigned long end, + struct mm_walk *walk) +{ + pte_t *pte; + spinlock_t *ptl; + struct page *page; + struct vm_area_struct *vma = walk->vma; + + ptl = pmd_trans_huge_lock(pmd, vma); + if (ptl) { + if (pmd_present(*pmd)) { + page = follow_trans_huge_pmd(vma, addr, pmd, + FOLL_DUMP|FOLL_WRITE); + if (!IS_ERR_OR_NULL(page)) + pte_page_idle_proc_add(page, addr, walk); + } + spin_unlock(ptl); + return 0; + } + + if (pmd_trans_unstable(pmd)) + return 0; + + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + for (; addr != end; pte++, addr += PAGE_SIZE) { + if (!pte_present(*pte)) + continue; + + page = vm_normal_page(vma, addr, *pte); + if (page) + pte_page_idle_proc_add(page, addr, walk); + } + + pte_unmap_unlock(pte - 1, ptl); + return 0; +} + +ssize_t page_idle_proc_generic(struct file *file, char __user *ubuff, + size_t count, loff_t *pos, int write) +{ + int ret; + char *buffer; + u64 *out; + unsigned long start_addr, end_addr, start_frame, end_frame; + struct mm_struct *mm = file->private_data; + struct mm_walk walk = { .pmd_entry = pte_page_idle_proc_range, }; + struct page_node *cur; + struct page_idle_proc_priv priv; + bool walk_error = false; + LIST_HEAD(idle_page_list); + + if (!mm || !mmget_not_zero(mm)) + return -EINVAL; + + if (count > PAGE_SIZE) + count = PAGE_SIZE; + + buffer = kzalloc(PAGE_SIZE, GFP_KERNEL); + if (!buffer) { + ret = -ENOMEM; + goto out_mmput; + } + out = (u64 *)buffer; + + if (write && copy_from_user(buffer, ubuff, count)) { + ret = -EFAULT; + goto out; + } + + ret = page_idle_get_frames(*pos, count, mm, &start_frame, &end_frame); + if (ret) + goto out; + + start_addr = (start_frame << PAGE_SHIFT); + end_addr = (end_frame << PAGE_SHIFT); + priv.buffer = buffer; + priv.start_addr = start_addr; + priv.write = write; + + priv.idle_page_list = &idle_page_list; + priv.cur_page_node = 0; + priv.page_nodes = kzalloc(sizeof(struct page_node) * + (end_frame - start_frame), GFP_KERNEL); + if (!priv.page_nodes) { + ret = -ENOMEM; + goto out; + } + + walk.private = &priv; + walk.mm = mm; + + down_read(&mm->mmap_sem); + + /* + * idle_page_list is needed because walk_page_vma() holds ptlock which + * deadlocks with page_idle_clear_pte_refs(). So we have to collect all + * pages first, and then call page_idle_clear_pte_refs(). + */ + ret = walk_page_range(start_addr, end_addr, &walk); + if (ret) + walk_error = true; + + list_for_each_entry(cur, &idle_page_list, list) { + int bit, index; + unsigned long off; + struct page *page = cur->page; + + if (unlikely(walk_error)) + goto remove_page; + + if (write) { + if (page) { + page_idle_clear_pte_refs(page); + set_page_idle(page); + } + } else { + if (page_idle_pte_check(page)) { + off = ((cur->addr) >> PAGE_SHIFT) - start_frame; + bit = off % BITMAP_CHUNK_BITS; + index = off / BITMAP_CHUNK_BITS; + out[index] |= 1ULL << bit; + } + } +remove_page: + if (page) + put_page(page); + } + + if (!write && !walk_error) + ret = copy_to_user(ubuff, buffer, count); + + up_read(&mm->mmap_sem); + kfree(priv.page_nodes); +out: + kfree(buffer); +out_mmput: + mmput(mm); + if (!ret) + ret = count; + return ret; + +} + +ssize_t page_idle_proc_read(struct file *file, char __user *ubuff, + size_t count, loff_t *pos) +{ + return page_idle_proc_generic(file, ubuff, count, pos, 0); +} + +ssize_t page_idle_proc_write(struct file *file, char __user *ubuff, + size_t count, loff_t *pos) +{ + return page_idle_proc_generic(file, ubuff, count, pos, 1); +} + static int __init page_idle_init(void) { int err;

[v5,1/6] mm/page_idle: Add per-pid idle page tracking using virtual index

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