From patchwork Fri Jul 26 15:08:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 11061207 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CCB5A13A0 for ; Fri, 26 Jul 2019 15:08:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B97AF28B30 for ; Fri, 26 Jul 2019 15:08:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id ACBFF28B35; Fri, 26 Jul 2019 15:08:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=unavailable version=3.3.1 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 891CE28A3D for ; Fri, 26 Jul 2019 15:08:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7997C6B0003; Fri, 26 Jul 2019 11:08:56 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 749416B0005; Fri, 26 Jul 2019 11:08:56 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5EB3A8E0002; Fri, 26 Jul 2019 11:08:56 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from mail-pg1-f199.google.com (mail-pg1-f199.google.com [209.85.215.199]) by kanga.kvack.org (Postfix) with ESMTP id 1B6986B0003 for ; Fri, 26 Jul 2019 11:08:56 -0400 (EDT) Received: by mail-pg1-f199.google.com with SMTP id x19so33171798pgx.1 for ; Fri, 26 Jul 2019 08:08:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:from:to:cc:subject:date :message-id:mime-version:content-transfer-encoding; bh=oiIh3ewyUN7r58YhEz3CTvh2WcWJZA4335Nt1iFVDU8=; b=YAvtGs0H5wPAXGQBcgYwcY/H46vkpB48f9XKz1B48EdrurLqTia80hgN6l2WHQbfGl /1b7jZVs6OSW7UUz/OYtyz9RhhemA7l9ZtmskD3YOSqRu5t9BZTNZjm2mSdpVjUIBR7S Hi0PnRMGNSfrP6WNbLhEdAO8mv7boxLdXXefJEZtVedGDper5uo7H3IzSpCWHOC8Royk G59RB1FEeGnhlGGyXJS1rlyh/ey5wYip6b0uG0/UHIjxHG7RWAqFZ+dMkrL0BZ339UfP 9fYPA5dqEfHIohHijXSB/CHXHwVDqsr6Yd98xPBX9eGyMVxLYx7Dt4nLrFXV7YnupIuv 7qOA== X-Gm-Message-State: APjAAAUXVvElpXqiPlo9cJfmsyYbDpS45KHEVR9JTndfcyMqYiSvVmzV xRmS6DJhB64xVtDPnIacblBRx4q5rK5newRXEZoUSGEkkhQs7llF2U6wJ1ddfXGYw9w7IITXL2W wGz/fND6V0IaqcZe9eqF2USeaA7c1057DmzpCyzZJeusPhqRcFIV7yrs2DCZ3R1j+Eg== X-Received: by 2002:a63:1d0e:: with SMTP id d14mr91606066pgd.324.1564153735584; Fri, 26 Jul 2019 08:08:55 -0700 (PDT) X-Received: by 2002:a63:1d0e:: with SMTP id d14mr91605948pgd.324.1564153734016; Fri, 26 Jul 2019 08:08:54 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1564153734; cv=none; d=google.com; s=arc-20160816; b=T0JabLelmzVYPNQjf5e2N+SJtOxYGP0MX4KEpkYznG0CUuNgADz4nN5IQPbbqC0qpe 7cJV2ZV0UkJozKixDKpBxNpmQ5Y5nOwua8qSw+wisKbQ05wGhk/gY6M9AQOaqaupWuFD VDGRMKoH58iKWX3wOSLAVOeBnFe6k9pi8HxD8Ky91KNfQDnkAvStadezsNntTlyICtN5 l+q1F/8+Vb6k6scmwKe/uH/CHnKGGDlFYuCfE6YSgv2Fpq/iuaHRfEpFJ34qJ/o/JlZS WmCv3YzPWR/WjMsmHHL/sAIVifxsmk+kOMTHTQRF99NYHi+C25yuIChBy0JNQ3QBrxiz JveA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:dkim-signature; bh=oiIh3ewyUN7r58YhEz3CTvh2WcWJZA4335Nt1iFVDU8=; b=CqLwNMAYBRleZAJ1OuJ3pNBpBfpbi7QHnExf908tWn60BZ+6QLftGWyjTY+KF8rVf5 xEL3Eam4sKhzuSXz89PKsVZ+5+RZqCy8qgBOgJo4K6jOh6S5Ct01L7xhJHXtSLuQng4I x01U4yh1uqANa9+icnlYSBQidIPl/kZxf1MclHmufd1/3LRJfOuQFsYVLmXlRTHVWmkf HzbMFLYt3YSSugKhlvW02STvM3p4W6ZpTiZrqhNavSo8kzJGMKiZf14Fzw+zBZZsz5HX /9HNu3jSE8c4/S8u7YB0w0M9vmjGmCksI1C+7JWbFzc/2jKiqptpYfQJMw0pAC8fzV1l 97Xw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@joelfernandes.org header.s=google header.b=Vfel5Oq3; spf=pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=joel@joelfernandes.org Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id k5sor63790245pjp.16.2019.07.26.08.08.53 for (Google Transport Security); Fri, 26 Jul 2019 08:08:54 -0700 (PDT) Received-SPF: pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@joelfernandes.org header.s=google header.b=Vfel5Oq3; spf=pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=joel@joelfernandes.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=oiIh3ewyUN7r58YhEz3CTvh2WcWJZA4335Nt1iFVDU8=; b=Vfel5Oq3rZKt3sFji52iOETMAh79j74S3OqcJ2If83AVw3LRfkjRQMAy+ZlecPkEup gZmDFULuUJbXMQVxBhxJB3/LpJ9I6n8Iu2B/H2rlAylG+m80k5+cbuFdCkgNcjxRiGbs KzsYbvBQS+Lh/iMtQaGRZfQ0CLVzoy6RJQCh4= X-Google-Smtp-Source: APXvYqzJUKkEXG3yx+rE4TNzeTKnko/lEMbNDX9gkLfn4oR9oZkmKS0MeAsXLN2HS0F7aH4wIa2tTQ== X-Received: by 2002:a17:90a:c391:: with SMTP id h17mr99333833pjt.131.1564153733367; Fri, 26 Jul 2019 08:08:53 -0700 (PDT) Received: from joelaf.cam.corp.google.com ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id k36sm54802352pgl.42.2019.07.26.08.08.50 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 26 Jul 2019 08:08:52 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , Alexey Dobriyan , Andrew Morton , Brendan Gregg , Christian Hansen , dancol@google.com, fmayer@google.com, joaodias@google.com, joelaf@google.com, Jonathan Corbet , Kees Cook , 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 , Mike Rapoport , minchan@kernel.org, namhyung@google.com, Roman Gushchin , Stephen Rothwell , surenb@google.com, tkjos@google.com, Vladimir Davydov , Vlastimil Babka , wvw@google.com Subject: [PATCH v2 1/2] mm/page_idle: Add per-pid idle page tracking using virtual indexing Date: Fri, 26 Jul 2019 11:08:43 -0400 Message-Id: <20190726150845.95720-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.22.0.709.g102302147b-goog MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP The page_idle tracking feature currently requires looking up the pagemap for a process followed by interacting with /sys/kernel/mm/page_idle. Looking up PFN from pagemap in Android devices is not supported by unprivileged process and requires SYS_ADMIN and gives 0 for the PFN. This patch adds support to directly interact with page_idle tracking at the PID level by introducing a /proc//page_idle file. It follows the exact same semantics as the global /sys/kernel/mm/page_idle, but now looking up PFN through pagemap is not needed since the interface uses virtual frame numbers, and at the same time also does not require SYS_ADMIN. In Android, we are using this for the heap profiler (heapprofd) which profiles and pin points code paths which allocates and leaves memory idle for long periods of time. This method solves the security issue with userspace learning the PFN, and while at it is also shown to yield better results than the pagemap lookup, the theory being that the window where the address space can change is reduced by eliminating the intermediate pagemap look up stage. In virtual address indexing, the process's mmap_sem is held for the duration of the access. Signed-off-by: Joel Fernandes (Google) Reported-by: kernel test robot --- v1 -> v2: Mark swap ptes as idle (Minchan) Avoid need for GFP_ATOMIC (Andrew) Get rid of idle_page_list lock by moving list to stack Internal review -> v1: Fixes from Suren. Corrections to change log, docs (Florian, Sandeep) fs/proc/base.c | 3 + fs/proc/internal.h | 1 + fs/proc/task_mmu.c | 57 +++++++ include/linux/page_idle.h | 4 + mm/page_idle.c | 342 +++++++++++++++++++++++++++++++++----- 5 files changed, 362 insertions(+), 45 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 77eb628ecc7f..a58dd74606e9 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3021,6 +3021,9 @@ 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 4d2b860dbc3f..11ccc53da38e 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1642,6 +1642,63 @@ 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) +{ + int ret; + struct task_struct *tsk = get_proc_task(file_inode(file)); + + if (!tsk) + return -EINVAL; + ret = page_idle_proc_read(file, buf, count, ppos, tsk); + put_task_struct(tsk); + return ret; +} + +static ssize_t proc_page_idle_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + int ret; + struct task_struct *tsk = get_proc_task(file_inode(file)); + + if (!tsk) + return -EINVAL; + ret = page_idle_proc_write(file, (char __user *)buf, count, ppos, tsk); + put_task_struct(tsk); + return ret; +} + +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; + + if (mm) + 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..f1bc2640d85e 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, struct task_struct *tsk); +ssize_t page_idle_proc_read(struct file *file, + char __user *buf, size_t count, loff_t *ppos, struct task_struct *tsk); #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..d8a14955c39d 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -5,12 +5,15 @@ #include #include #include -#include -#include -#include #include +#include #include #include +#include +#include +#include +#include +#include #define BITMAP_CHUNK_SIZE sizeof(u64) #define BITMAP_CHUNK_BITS (BITMAP_CHUNK_SIZE * BITS_PER_BYTE) @@ -25,18 +28,13 @@ * 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 +49,18 @@ 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 +128,47 @@ 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_really_idle(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 +176,21 @@ 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_really_idle(page)) { + *out |= 1ULL << bit; put_page(page); } if (bit == BITMAP_CHUNK_BITS - 1) @@ -170,23 +207,16 @@ 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 +254,228 @@ struct page_ext_operations page_idle_ops = { }; #endif +/* page_idle tracking for /proc//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 add_page_idle_list() */ + struct page_node *page_nodes; + int cur_page_node; + struct list_head *idle_page_list; +}; + +/* + * Add a page to the idle page list. page can be NULL if pte is + * from a swapped page. + */ +static void add_page_idle_list(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) { + /* 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; + } + + 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) +{ + struct vm_area_struct *vma = walk->vma; + pte_t *pte; + spinlock_t *ptl; + struct page *page; + + 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)) + add_page_idle_list(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) { + /* + * We add swapped pages to the idle_page_list so that we can + * reported to userspace that they are idle. + */ + if (is_swap_pte(*pte)) { + add_page_idle_list(NULL, addr, walk); + continue; + } + + if (!pte_present(*pte)) + continue; + + page = vm_normal_page(vma, addr, *pte); + if (page) + add_page_idle_list(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, + struct task_struct *tsk, 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, *next; + 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_safe(cur, next, &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 || page_really_idle(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); + list_del(&cur->list); + kfree(cur); + } + + 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, struct task_struct *tsk) +{ + return page_idle_proc_generic(file, ubuff, count, pos, tsk, 0); +} + +ssize_t page_idle_proc_write(struct file *file, char __user *ubuff, + size_t count, loff_t *pos, struct task_struct *tsk) +{ + return page_idle_proc_generic(file, ubuff, count, pos, tsk, 1); +} + static int __init page_idle_init(void) { int err;