From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7F719C00144 for ; Mon, 1 Aug 2022 10:53:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230366AbiHAKx2 (ORCPT ); Mon, 1 Aug 2022 06:53:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51580 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230042AbiHAKxX (ORCPT ); Mon, 1 Aug 2022 06:53:23 -0400 Received: from out30-56.freemail.mail.aliyun.com (out30-56.freemail.mail.aliyun.com [115.124.30.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D73729803 for ; Mon, 1 Aug 2022 03:53:21 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R151e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046059;MF=xhao@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0VL5xOVg_1659351196; Received: from 30.240.98.221(mailfrom:xhao@linux.alibaba.com fp:SMTPD_---0VL5xOVg_1659351196) by smtp.aliyun-inc.com; Mon, 01 Aug 2022 18:53:18 +0800 Message-ID: <53793484-07a4-edab-652d-06e5e28521d8@linux.alibaba.com> Date: Mon, 1 Aug 2022 18:53:16 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.0.3 Subject: Re: [RFC V3 PATCH] mm: add last level page table numa info to /proc/pid/numa_pgtable To: Baolin Wang , willy@infradead.org Cc: akpm@linux-foundation.org, adobriyan@gmail.com, keescook@chromium.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20220801032704.64356-1-xhao@linux.alibaba.com> From: haoxin In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/8/1 下午2:06, Baolin Wang 写道: > Hi Xin, > > On 8/1/2022 11:27 AM, Xin Hao wrote: >> In many data center servers, the shared memory architectures is >> Non-Uniform Memory Access (NUMA), remote numa node data access >> often brings a high latency problem, but what we are easy to ignore >> is that the page table remote numa access, It can also leads to a >> performance degradation. >> >> So there add a new interface in /proc, This will help developers to >> get more info about performance issues if they are caused by cross-NUMA. >> >> V2 -> V3 >> 1, Fix compile warning bug. >> >> V1 -> V2 >> 1, As Matthew Wilcox advise, Simplify the code. >> 2, Do some codes format fix. > > Please move the changes history under your 'Signed-off-by' with '---'. > >> >> V2: >> https://lore.kernel.org/linux-mm/20220731155223.60238-1-xhao@linux.alibaba.com/ >> V1: >> https://lore.kernel.org/linux-mm/YuVqdcY8Ibib2LJa@casper.infradead.org/T/ >> >> Reported-by: kernel test robot >> Signed-off-by: Xin Hao >> --- >>   fs/proc/base.c     |  2 ++ >>   fs/proc/internal.h |  1 + >>   fs/proc/task_mmu.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++ >>   3 files changed, 90 insertions(+) >> >> diff --git a/fs/proc/base.c b/fs/proc/base.c >> index 8dfa36a99c74..487e82dd3275 100644 >> --- a/fs/proc/base.c >> +++ b/fs/proc/base.c >> @@ -3224,6 +3224,7 @@ static const struct pid_entry tgid_base_stuff[] >> = { >>       REG("maps",       S_IRUGO, proc_pid_maps_operations), >>   #ifdef CONFIG_NUMA >>       REG("numa_maps",  S_IRUGO, proc_pid_numa_maps_operations), >> +    REG("numa_pgtable", S_IRUGO, proc_pid_numa_pgtable_operations), >>   #endif >>       REG("mem",        S_IRUSR|S_IWUSR, proc_mem_operations), >>       LNK("cwd",        proc_cwd_link), >> @@ -3571,6 +3572,7 @@ static const struct pid_entry tid_base_stuff[] = { >>   #endif >>   #ifdef CONFIG_NUMA >>       REG("numa_maps", S_IRUGO, proc_pid_numa_maps_operations), >> +    REG("numa_pgtable", S_IRUGO, proc_pid_numa_pgtable_operations), >>   #endif >>       REG("mem",       S_IRUSR|S_IWUSR, proc_mem_operations), >>       LNK("cwd",       proc_cwd_link), >> diff --git a/fs/proc/internal.h b/fs/proc/internal.h >> index 06a80f78433d..e7ed9ef097b6 100644 >> --- a/fs/proc/internal.h >> +++ b/fs/proc/internal.h >> @@ -296,6 +296,7 @@ struct mm_struct *proc_mem_open(struct inode >> *inode, unsigned int mode); >> >>   extern const struct file_operations proc_pid_maps_operations; >>   extern const struct file_operations proc_pid_numa_maps_operations; >> +extern const struct file_operations proc_pid_numa_pgtable_operations; >>   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; >> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c >> index 2d04e3470d4c..77b7a49757f5 100644 >> --- a/fs/proc/task_mmu.c >> +++ b/fs/proc/task_mmu.c >> @@ -1999,4 +1999,91 @@ const struct file_operations >> proc_pid_numa_maps_operations = { >>       .release    = proc_map_release, >>   }; >> >> +struct pgtable_numa_private { >> +    struct proc_maps_private proc_maps; >> +    unsigned long node[MAX_NUMNODES]; >> +}; >> + >> +static int gather_pgtable_numa_stats(pmd_t *pmd, unsigned long addr, >> +                     unsigned long end, struct mm_walk *walk) >> +{ >> +    struct pgtable_numa_private *priv = walk->private; >> +    struct page *page; >> +    int nid; >> + >> +    if (pmd_huge(*pmd)) { >> +        page = virt_to_page(pmd); >> +    } else { >> +        page = pmd_page(*pmd); > > You should validate if the pmd is valid or present before getting the > pagetable page. > > if (pmd_none(*pmd) || !pmd_present(*pmd)) > > Another issue is I think you should hold the pmd lock to call > pmd_page(), since after the validation of pmd_huge(), the pmd entry > can be modified by other threads if you did not hold the pmd lock. > Thanks, Baolin, i will fix it in the next version. >> +    } >> + >> +    nid = page_to_nid(page); >> +    priv->node[nid]++; >> + >> +    return 0; >> +} >> + >> +static const struct mm_walk_ops show_numa_pgtable_ops = { >> +    .pmd_entry = gather_pgtable_numa_stats, >> +}; >> + >> +/* >> + * Display the page talbe allocated per node via /proc. >> + */ >> +static int show_numa_pgtable(struct seq_file *m, void *v) >> +{ >> +    struct pgtable_numa_private *numa_priv = m->private; >> +    struct vm_area_struct *vma = v; >> +    struct mm_struct *mm = vma->vm_mm; >> +    struct file *file = vma->vm_file; >> +    int nid; >> + >> +    if (!mm) >> +        return 0; >> + >> +    memset(numa_priv->node, 0, sizeof(numa_priv->node)); >> + >> +    seq_printf(m, "%08lx ", vma->vm_start); >> + >> +    if (file) { >> +        seq_puts(m, " file="); >> +        seq_file_path(m, file, "\n\t= "); >> +    } else if (vma->vm_start <= mm->brk && vma->vm_end >= >> mm->start_brk) { >> +        seq_puts(m, " heap"); >> +    } else if (is_stack(vma)) { >> +        seq_puts(m, " stack"); >> +    } >> + >> +    /* mmap_lock is held by m_start */ >> +    walk_page_vma(vma, &show_numa_pgtable_ops, numa_priv); >> + >> +    for_each_node_state(nid, N_MEMORY) { >> +        if (numa_priv->node[nid]) >> +            seq_printf(m, " N%d=%lu", nid, numa_priv->node[nid]); >> +    } >> +    seq_putc(m, '\n'); >> + >> +    return 0; >> +} >> + >> +static const struct seq_operations proc_pid_numa_pgtable_op = { >> +    .start  = m_start, >> +    .next   = m_next, >> +    .stop   = m_stop, >> +    .show   = show_numa_pgtable, >> +}; >> + >> +static int pid_numa_pgtable_open(struct inode *inode, struct file >> *file) >> +{ >> +    return proc_maps_open(inode, file, &proc_pid_numa_pgtable_op, >> +            sizeof(struct pgtable_numa_private)); >> +} >> + >> +const struct file_operations proc_pid_numa_pgtable_operations = { >> +    .open        = pid_numa_pgtable_open, >> +    .read        = seq_read, >> +    .llseek        = seq_lseek, >> +    .release    = proc_map_release, >> +}; >> + >>   #endif /* CONFIG_NUMA */ >> -- >> 2.31.0