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 14C66CA5537 for ; Wed, 13 Sep 2023 10:59:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6920B6B0183; Wed, 13 Sep 2023 06:59:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 641F06B0184; Wed, 13 Sep 2023 06:59:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 50AB16B0185; Wed, 13 Sep 2023 06:59:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 403376B0183 for ; Wed, 13 Sep 2023 06:59:57 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 148F91A0DCE for ; Wed, 13 Sep 2023 10:59:57 +0000 (UTC) X-FDA: 81231279234.29.A3ABD44 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf22.hostedemail.com (Postfix) with ESMTP id 4A1C7C0002 for ; Wed, 13 Sep 2023 10:59:55 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=gYPRVK+v; spf=pass (imf22.hostedemail.com: domain of bhe@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=bhe@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1694602795; a=rsa-sha256; cv=none; b=hKH/2ceZ+/sfWB805LI86Rl7SbJ+PhvSTpcQKiriqvjT1Defk4l4agd+ilkioLxkT5GnQC ofSx09MURhsdASF4TQyMdSXxYceGno8Z+170ymCKuiKSeB61WidDAc7k0EiOyoexliD555 b6VpUdH27fj+G6V7XfnjyyFzNwmQVqA= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=gYPRVK+v; spf=pass (imf22.hostedemail.com: domain of bhe@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=bhe@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1694602795; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=KB7mfwMZ7mYpt2Xc/Lhnjng9uCFOHUfEHeblSFIjfOA=; b=dYkG8PaMoWr4VhwSyRZtxMZiAlO64tfzNam83k3UE2yoJ/8OtbFJPW3fnoF1VJ1bQYxnyS JWdAeLSa2zpVqJ8WAxCLlK1WQso7IQovGioxcJ2AatGRb5iMOnDQf4qBB69mQhBsNglDvF /pAZWm65BDc+iqcKTSMZgC1e5wwHxmg= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1694602794; 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: in-reply-to:in-reply-to:references:references; bh=KB7mfwMZ7mYpt2Xc/Lhnjng9uCFOHUfEHeblSFIjfOA=; b=gYPRVK+v4oA9g7PNgc4GksiMusyNzFENsGP8qtET2DpLZqtLp7usM2HHNuE5JqqsuFvFFo BOgrp4zeCD6EHai+D+OnvWV5JaAQVhD67k4XMrtZk32n7b03OEnlV3rJyUel34aykXvfA2 hakSWF4sZv1YM0eezEbWL1HhM1VBAqQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-308-oPatIiEkODymXrupV_m8vg-1; Wed, 13 Sep 2023 06:59:48 -0400 X-MC-Unique: oPatIiEkODymXrupV_m8vg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 75D84101A550; Wed, 13 Sep 2023 10:59:47 +0000 (UTC) Received: from localhost (unknown [10.72.112.36]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 85A3740AE2C0; Wed, 13 Sep 2023 10:59:46 +0000 (UTC) Date: Wed, 13 Sep 2023 18:59:42 +0800 From: Baoquan He To: Uladzislau Rezki Cc: linux-mm@kvack.org, Andrew Morton , LKML , Lorenzo Stoakes , Christoph Hellwig , Matthew Wilcox , "Liam R . Howlett" , Dave Chinner , "Paul E . McKenney" , Joel Fernandes , Oleksiy Avramchenko Subject: Re: [PATCH v2 7/9] mm: vmalloc: Support multiple nodes in vread_iter Message-ID: References: <20230829081142.3619-1-urezki@gmail.com> <20230829081142.3619-8-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 4A1C7C0002 X-Stat-Signature: 9smm4nrqyop84f8qhparhongadcrdttz X-Rspam-User: X-HE-Tag: 1694602795-846613 X-HE-Meta: U2FsdGVkX1+4gNh6UzlLVlyKC6CeH1+2s9ybeFWVbxlP7cK861DcjPPtm4TBu4D91WTNImSO6TkCaCMNAZp9cdIe7gi+/EK0kjbnuhn0fwcjRKYKZC8LMmtIcyZ7LeQOYyIPpzGY568LAF8EujtyHY8+czmwP7AZgNlb5diwzFY/9WEJYClQZ+MXqsmDwnS0lPschGPhv/XGHf5tzsIEybUtFGyJSLLN2a/MKcjs3t4/CITFj5g5Dqj1PxDiaKsHWkiD2jtmkU0oKoBG+ZY8U/YIdL5n+Jl1/yD1TlY0xs8X8wSqgRJai6wnRShQVKulA0voLS8/UlIqndm9dSRHvhx9BcNMt/Cyv81QODzvPCeEDQgHAiiYX1JFNXEFEKtdIk6ezy/JZfXzFPXMuotLvNrNwN11eMdpnf000KbOwu/ZTLM4yMmQ1tCZeKIu3xP/KLXR+byZgC+TJ7f70RcpQbaNx0sIxB9Z2/55R0aGNdGwtGLc8kKY2DttU79/3CFUzlrC1X/uZ2tVwui9++Rkc452IVli6nBGALIfc0iTUi4bxqpTHq+ky4cjTG0nNTsmsnDWroprqVh102GeZx71iS8FPLIyIx/FxATnL9nfpaomkkbmYdF1FCOIoGRv+ZOpUc/aawmyS2x3Nc/hz56BN5m4/pFiIu0IsLO/BucJPV9diPeDC+PsZPhFEqnaCfmyptyybBPjleeGLguTJGlStDoyME+v5Npx2n66OMRO3++umUmVt1QIp0GYbkZAII68AXHtXsV/+kzt0AHQYwHNLiC8iEQKfsBm7qV025kNrLU1CfZXQevCbXfnXfXe/ix0T8RTmy9ooQuuScp3oWovGVvDDJDHvJa/qZNo6dcNf5nr32ZSDJGcWgapdYDU5JqUeywMsFRGAhopEJbN0vDwWd+Y6YlSKhItdIjOzxrqYKPMZlt+UzhoaoOX7TBpcWMmml3ea6tZC6k8JkSJD0Y xzXemRgO OzNTvOkb6QV+ZYVlMSGUFWkV2wlcWt+AZUERnOMeBrQ2oi+kaeLKvRWiUiwIbwROYJi4FGgOn88VxkU95/L7MfGmNZ8Km42Nk/5Y+npVkv1Ol6qRCfog433q05KzD26nvSOvPPXQl9Fc/PeH+Rk9fIOY0CvaWzxzEZaWdxxlaucMtaLLxQQI8WGC7y6tSMAepB66u+n7hrdrwqhfSHNGVbQ3l9r91mFpLF0WmGlkZTJuxG5TpEECgnE4btWb1FsmR/3qQ0vbAzXRxTWo= 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: On 09/11/23 at 08:16pm, Uladzislau Rezki wrote: > On Mon, Sep 11, 2023 at 11:58:13AM +0800, Baoquan He wrote: > > On 08/29/23 at 10:11am, Uladzislau Rezki (Sony) wrote: > > > Extend the vread_iter() to be able to perform a sequential > > > reading of VAs which are spread among multiple nodes. So a > > > data read over the /dev/kmem correctly reflects a vmalloc > > > memory layout. > > > > > > Signed-off-by: Uladzislau Rezki (Sony) > > > --- > > > mm/vmalloc.c | 67 +++++++++++++++++++++++++++++++++++++++++----------- > > > 1 file changed, 53 insertions(+), 14 deletions(-) > > > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > > index 4fd4915c532d..968144c16237 100644 > > > --- a/mm/vmalloc.c > > > +++ b/mm/vmalloc.c > > ...... > > > @@ -4057,19 +4093,15 @@ long vread_iter(struct iov_iter *iter, const char *addr, size_t count) > > > > > > remains = count; > > > > > > - /* Hooked to node_0 so far. */ > > > - vn = addr_to_node(0); > > > - spin_lock(&vn->busy.lock); > > > > This could change the vread behaviour a little bit. Before, once we take > > vmap_area_lock, the vread will read out the content of snapshot at the > > moment. Now, reading out in one node's tree won't disrupt other nodes' > > tree accessing. Not sure if this matters when people need access > > /proc/kcore, e.g dynamic debugging. > > > With one big tree you anyway drop the lock after one cycle of reading. > As far as i see, kcore.c's read granularity is a PAGE_SIZE. You are right, kcore.c's reading granularity is truly PAGE_SIZE. I don't know procfs well, still need to study the code. Then it doesn't matter much with the multiple nodes in vread_iter(). Sorry for the noise. static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) { ...... start = kc_offset_to_vaddr(*fpos - data_offset); if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) tsz = buflen; m = NULL; while (buflen) { } ... }