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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 553F4E77160 for ; Wed, 4 Dec 2024 00:56:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B69BA6B007B; Tue, 3 Dec 2024 19:56:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B19156B0082; Tue, 3 Dec 2024 19:56:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A07AC6B0083; Tue, 3 Dec 2024 19:56:47 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 848A96B007B for ; Tue, 3 Dec 2024 19:56:47 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 30D361C7741 for ; Wed, 4 Dec 2024 00:56:47 +0000 (UTC) X-FDA: 82855461360.18.BFA3442 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf15.hostedemail.com (Postfix) with ESMTP id 4722EA000A for ; Wed, 4 Dec 2024 00:56:31 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=RNfxo4BL; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1733273792; a=rsa-sha256; cv=none; b=3S5MfLI4fAlvw5HjK+gW0p0C226EE8jLvhNb/qfBTDBIK+uW3Wqo0HzNhIbyBYp1Dm4+CG 88uJkrL6prQ3ZrDibELHlzRuvD/+QoqTnQ9CYgl/PRrnSWPC2FpzYwkNh9SrihzQO1cToN fVlEUHeOMNAcvN8EoWfHNhQlt7vSJ74= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=RNfxo4BL; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1733273792; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=EnUZ6xuFQUCJBPcQctZ0DdbhLWWsWbS3NVeLn6sg63c=; b=NMTsl8jH9RiexBVNPbnumNJx6Ti/UbUkYju/zjr9oAaFsTF8aRTeT4orn5kmELd70dNqir EMsM1ptYLZRVkuZrTUYIooyrrLnRoGDOd8EJpA9S1apo/KW1sCU6+api0e0UbNUVXag8tR Tw7izjoLf4pookPSKJ8F3ppFffJfPl0= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 4EB675C5FB5; Wed, 4 Dec 2024 00:56:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B322CC4CEDC; Wed, 4 Dec 2024 00:56:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1733273804; bh=HnvD9nA5AHCdsg9zPRJracg67gYt4epRVs62bCOVlMA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=RNfxo4BLUORttXowEY/7Lb2NtXEKxZtj3iKtvpYt/poJyguBqduECGWz1N8tINRAc WFjnTjrJKroELMzVPc8mYFNNl19IFv9ErROqnFh+NvfCVS3OKh8glphGPD9Q2t9Rwf kuaYEet47sLB+XbLGaCrMymvQZSx5TIoN6cnPVsg= Date: Tue, 3 Dec 2024 16:56:43 -0800 From: Andrew Morton To: Cc: , , , , Subject: Re: [PATCH linux-next v4] ksm: add ksm involvement information for each process Message-Id: <20241203165643.729e6c5fe58f59adc7ee098f@linux-foundation.org> In-Reply-To: <20241203192633836RVHhkoK1Amnqjt84D4Ryd@zte.com.cn> References: <20241203192633836RVHhkoK1Amnqjt84D4Ryd@zte.com.cn> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4722EA000A X-Stat-Signature: 7fmo31qfcdumxn7tbux34h7jefuygksw X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1733273791-491613 X-HE-Meta: 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 Xbbx0ai5 TuuDOyy36C8te8WGTiUfEgH9M8n8Ir/XOZQ+Wl3bZd3ZURe9onrR3fK9xuM+f+NQb7atExlCt+RpzMqcs04oKDNF9C0cgugbcXU8woYMWAfswVGk1qKu6mzIO0h7D+Tro944HJFxTKRk0aH3/twRgclZMG4k1Qesvcw0nNhznyPcqJcLb3176j6h2iJGXse0wTc9vNBMDL/ZLHLVtBm7W0cmVz4K31tgEdJhjc9YT5cLl0VCf+VA1egdVpoS8I5LvB+vVUdO+HQaPsuqyXrPlH5q5N5TgNK62bZCaL1VBBNlvhmnk2LOTZYj32w== 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: List-Subscribe: List-Unsubscribe: On Tue, 3 Dec 2024 19:26:33 +0800 (CST) wrote: > From: xu xin > > In /proc//ksm_stat, Add two extra ksm involvement items including > KSM_mergeable and KSM_merge_any. It helps administrators to > better know the system's KSM behavior at process level. It's hard for me to judge the usefulness of this. Please tell us more: usage examples, what actions have been taken using this information, etc. > KSM_mergeable: yes/no > whether any VMAs of the process'mm are currently applicable to KSM. Could we simply display VM_MERGEABLE in /proc//maps? > KSM_merge_any: yes/no > whether the process'mm is added by prctl() into the candidate list > of KSM or not, and fully enabled at process level. > > ... > > fs/proc/base.c | 11 +++++++++++ > include/linux/ksm.h | 1 + > mm/ksm.c | 19 +++++++++++++++++++ Documentation/admin-guide/mm/ksm.rst will require an update please. > > ... > > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -3269,6 +3269,7 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns, > struct pid *pid, struct task_struct *task) > { > struct mm_struct *mm; > + int ret = 0; > > mm = get_task_mm(task); > if (mm) { > @@ -3276,6 +3277,16 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns, > seq_printf(m, "ksm_zero_pages %ld\n", mm_ksm_zero_pages(mm)); > seq_printf(m, "ksm_merging_pages %lu\n", mm->ksm_merging_pages); > seq_printf(m, "ksm_process_profit %ld\n", ksm_process_profit(mm)); > + seq_printf(m, "ksm_merge_any: %s\n", > + test_bit(MMF_VM_MERGE_ANY, &mm->flags) ? "yes" : "no"); > + ret = mmap_read_lock_killable(mm); Could do the locking in ksm_process_mergeable()? > + if (ret) { > + mmput(mm); > + return ret; > + } > + seq_printf(m, "ksm_mergeable: %s\n", > + ksm_process_mergeable(mm) ? "yes" : "no"); Calling seq_printf() after the mmap_read_unlock() would be a little more scalable. > + mmap_read_unlock(mm); > mmput(mm); > } > > ... > > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -3263,6 +3263,25 @@ static void wait_while_offlining(void) > #endif /* CONFIG_MEMORY_HOTREMOVE */ > > #ifdef CONFIG_PROC_FS > +/* > + * The process is mergeable only if any VMA (and which) is currently > + * applicable to KSM. That sentence needs revisiting, please. > + * The mmap lock must be held in read mode. > + */ > +bool ksm_process_mergeable(struct mm_struct *mm) > +{ > + struct vm_area_struct *vma; > + > + mmap_assert_locked(mm); > + VMA_ITERATOR(vmi, mm, 0); > + for_each_vma(vmi, vma) > + if (vma->vm_flags & VM_MERGEABLE) > + return true; > + > + return false; > +}