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 216A8C04FFE for ; Wed, 8 May 2024 13:52:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AEDEA6B0089; Wed, 8 May 2024 09:52:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A9E4D6B008C; Wed, 8 May 2024 09:52:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 98CC86B0092; Wed, 8 May 2024 09:52:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 7B0406B0089 for ; Wed, 8 May 2024 09:52:54 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id E958CC10D2 for ; Wed, 8 May 2024 13:52:53 +0000 (UTC) X-FDA: 82095369426.07.C95C41D Received: from out-175.mta1.migadu.com (out-175.mta1.migadu.com [95.215.58.175]) by imf08.hostedemail.com (Postfix) with ESMTP id E4346160004 for ; Wed, 8 May 2024 13:52:51 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="OiQpH/u4"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf08.hostedemail.com: domain of chengming.zhou@linux.dev designates 95.215.58.175 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1715176372; 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=X6nBa8Swb0pQAYgPUFjA9k+jIGdbE8D0Y0wHnw+ROds=; b=G0v8PZhwadX8MLCzCdMOKx6KEjrSW+NyqNqxW9ISFIWXF2P/SgTdmxicDwTrylh3JsdNzn xn4MsjTK6LammDFf+rXu+t7N9stGoqDEf/hZG7it6QNTxlF2uYDO3NQ04tEdd2z9zuBjDg 9RSRjD/5/spx63T681Y6UCD/fXIwdks= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1715176372; a=rsa-sha256; cv=none; b=5av/6uRQrK2HpWVkAvDbS+HbUCsAmXWqwL98ePOEb9od4nfvw/b/IGYr5jy8H+1DJZg6T4 sGMyh25AfdzlZzQ9zhmrp0r/BQ5N3m7k9n6KZQV/Vll7yRiWGWchwLZF76iP/e86Harl9t LWcjQc0LdY9GXWZr8KKMDXSBHGUkOfY= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="OiQpH/u4"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf08.hostedemail.com: domain of chengming.zhou@linux.dev designates 95.215.58.175 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev Message-ID: <7d8ad19a-dae8-4783-8f49-227ef8ca4857@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1715176369; h=from:from: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; bh=X6nBa8Swb0pQAYgPUFjA9k+jIGdbE8D0Y0wHnw+ROds=; b=OiQpH/u4G74Br/DFrLL00699DNL62Tz4R1572g80K14ELUPcecmBqayJGmomJPpcCvYbTU 9Cviqgs0cW3KN5kACszgo5zWUFaecBLIlLe9ehbI/uLN1df8aitjKdkUXpgiGKWrCKt1RQ OLYkMP/4SCWFuMl5N7gf2DcaOAeJyAk= Date: Wed, 8 May 2024 21:52:20 +0800 MIME-Version: 1.0 Subject: Re: [PATCH 2/4] mm/ksm: fix ksm_zero_pages accounting Content-Language: en-US To: David Hildenbrand , Andrew Morton , Stefan Roesch , xu xin Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, zhouchengming@bytedance.com References: <20240508-b4-ksm-counters-v1-0-e2a9b13f70c5@linux.dev> <20240508-b4-ksm-counters-v1-2-e2a9b13f70c5@linux.dev> <7cac6762-4486-4c42-885d-dd5715eb6ba4@redhat.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: <7cac6762-4486-4c42-885d-dd5715eb6ba4@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: E4346160004 X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: cet6zphbshg6d38qwij6rwzk7r4hsu3w X-HE-Tag: 1715176371-853278 X-HE-Meta: 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 T2KMlcD8 gCkKXG/Wc4zL1mIh8qm8psgi2wpcRMS91LhjX2r9ftzU7b6afbZ9xgfx/878K+q8xgsWXXnE7Ptiw8CdFLU5zrf2GvSFxgj23cMeaoR+vMG4yrAZLgTo0jFx7udT+axA1MarMcvBcAtznETSotWIFVDN7g/KYBK1SBu+MZ30VLVu0n9bPy4WOsLVrYQ== 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 2024/5/8 20:36, David Hildenbrand wrote: > On 08.05.24 11:55, Chengming Zhou wrote: >> We normally ksm_zero_pages++ in ksmd when page is merged with zero page, >> but ksm_zero_pages-- is done from page tables side, which can't protected >> by the ksmd mutex. >> >> So we can read very exceptional value of ksm_zero_pages in rare cases, >> such as -1, which is very confusing to users. >> >> Fix it by changing to use atomic_long_t, and the same case with the >> mm->ksm_zero_pages. >> >> Signed-off-by: Chengming Zhou >> --- >>   fs/proc/base.c           |  2 +- >>   include/linux/ksm.h      | 22 +++++++++++++++++++--- >>   include/linux/mm_types.h |  2 +- >>   mm/ksm.c                 | 11 +++++------ >>   4 files changed, 26 insertions(+), 11 deletions(-) >> >> diff --git a/fs/proc/base.c b/fs/proc/base.c >> index 18550c071d71..72a1acd03675 100644 >> --- a/fs/proc/base.c >> +++ b/fs/proc/base.c >> @@ -3214,7 +3214,7 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns, >>       mm = get_task_mm(task); >>       if (mm) { >>           seq_printf(m, "ksm_rmap_items %lu\n", mm->ksm_rmap_items); >> -        seq_printf(m, "ksm_zero_pages %lu\n", mm->ksm_zero_pages); >> +        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)); >>           mmput(mm); >> diff --git a/include/linux/ksm.h b/include/linux/ksm.h >> index 52c63a9c5a9c..bfc2cf756b0d 100644 >> --- a/include/linux/ksm.h >> +++ b/include/linux/ksm.h >> @@ -33,16 +33,32 @@ void __ksm_exit(struct mm_struct *mm); >>    */ >>   #define is_ksm_zero_pte(pte)    (is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte)) >>   -extern unsigned long ksm_zero_pages; >> +extern atomic_long_t ksm_zero_pages; >> + >> +static inline void ksm_map_zero_page(struct mm_struct *mm) >> +{ >> +    atomic_long_inc(&ksm_zero_pages); >> +    atomic_long_inc(&mm->ksm_zero_pages); >> +} >>     static inline void ksm_might_unmap_zero_page(struct mm_struct *mm, pte_t pte) >>   { >>       if (is_ksm_zero_pte(pte)) { >> -        ksm_zero_pages--; >> -        mm->ksm_zero_pages--; >> +        atomic_long_dec(&ksm_zero_pages); >> +        atomic_long_dec(&mm->ksm_zero_pages); >>       } >>   } >>   +static inline long get_ksm_zero_pages(void) >> +{ >> +    return atomic_long_read(&ksm_zero_pages); >> +} > > I suggest inlining that one. The naming of the function also is a bit inconsistent staring at the others. Good point, I will inline it. > >> + >> +static inline long mm_ksm_zero_pages(struct mm_struct *mm) >> +{ >> +    return atomic_long_read(&mm->ksm_zero_pages); >> +} >> + > > Apart from that LGTM > > Acked-by: David Hildenbrand > Thanks!