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 0E090EB64DD for ; Mon, 14 Aug 2023 18:12:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 663DA8E0003; Mon, 14 Aug 2023 14:12:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6135F8E0001; Mon, 14 Aug 2023 14:12:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4DB1E8E0003; Mon, 14 Aug 2023 14:12:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 3E7278E0001 for ; Mon, 14 Aug 2023 14:12:11 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 17B5C1C91C2 for ; Mon, 14 Aug 2023 18:12:11 +0000 (UTC) X-FDA: 81123504462.06.93617E9 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf25.hostedemail.com (Postfix) with ESMTP id 20B38A0005 for ; Mon, 14 Aug 2023 18:12:07 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="CVS/0pxH"; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf25.hostedemail.com: domain of oleg@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=oleg@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1692036728; 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=T+yOj+yKntgsG0drgyyHIA7iDO2ZYuAK+/lXEF9ROjw=; b=0/b3W0N61aIpSZX156u5Y2cS0AClN0Oz74rNXvva7z1n7h0icWofZyi/wIDn6aMaXHjj5f vMHPcZXuTKb2mcLE5G9iByuQNO1m3lqTfLC+oiLA9toY3yLyf7Ug4bEaN5wQhvbJbhZQOE lLuO9caoMW9+YTgMsIPVoyDXimsCSl8= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="CVS/0pxH"; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf25.hostedemail.com: domain of oleg@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=oleg@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1692036728; a=rsa-sha256; cv=none; b=drrNwenvazsGlRbJg0Q2uJn1QxDv/FexR61Twjc2xEa3uU8RWYZZHoK6higYymqa2kafb1 xu1uJ8505z2xP01CUNcr26AtAG/QJs0vFv9hYmjFmuREpOh62oG/5pWowkmquscwh1dnf0 HME6IBXlUwadIr3ZLiKqfdEVw+2/KjA= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1692036727; 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=T+yOj+yKntgsG0drgyyHIA7iDO2ZYuAK+/lXEF9ROjw=; b=CVS/0pxHZeh9t4EZMM61HMDIfR1XK5PPYLBeM9vXlt2+NRi4VZB8oZybk1rynfo6UNrPQh HAUj/ANth95ks5y2L1fVoyEs4nWdxB6yAAui22J7HxZnlu7ucA04yrZhns7Nd+0OIajXqO 3B771ddaJP6oWXN9iOS6jjQkpVsirF8= Received: from mimecast-mx02.redhat.com (66.187.233.73 [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-671-_al0oEUfMy2UoQY_hzhk1g-1; Mon, 14 Aug 2023 14:12:01 -0400 X-MC-Unique: _al0oEUfMy2UoQY_hzhk1g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C6FE21C03D86; Mon, 14 Aug 2023 18:12:00 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.225.27]) by smtp.corp.redhat.com (Postfix) with SMTP id 53E3040C2063; Mon, 14 Aug 2023 18:11:58 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 14 Aug 2023 20:11:18 +0200 (CEST) Date: Mon, 14 Aug 2023 20:11:15 +0200 From: Oleg Nesterov To: Mateusz Guzik Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, brauner@kernel.org, ebiederm@xmission.com, david@redhat.com, akpm@linux-foundation.org, linux-mm@kvack.org, koct9i@gmail.com, dave@stgolabs.net Subject: Re: [PATCH v2] kernel/fork: stop playing lockless games for exe_file replacement Message-ID: <20230814181114.GD17738@redhat.com> References: <20230814172140.1777161-1-mjguzik@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230814172140.1777161-1-mjguzik@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Rspamd-Queue-Id: 20B38A0005 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: f3khxdh3hkhhsmjkxfqzgyxuhidwtjwt X-HE-Tag: 1692036727-341897 X-HE-Meta: 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 669vUIbI Jkfs2vHnbOC1euEpO0YxiLtbeUID9jB+IKLC2odZYlWSESQQFIFSoRik0lRzyVfkIoOw5opZkCzmyh0NlXRfvxi8gUnNuLRyO7yLMyXyvr02XzO8w4cV9NwEOETQZNjpL/LRzXUs3LXPH6MhD1tsNwSt5UqGyaTQ8QtHQmqeLZSN2lo2GprTIOIcZyjBI6KHb+Qy2uc4AUcPdFj7G+jdP9CFCzEcx+AtpvBclKANXrpPbs4I228k7GUYQpD/cQGv9A530R6UKVohhVkzMjTZLbXbV2h4XL8a3hGKZvBp2/TBUy3o5oXXDHc5KUw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000013, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 08/14, Mateusz Guzik wrote: > > However, fe69d560b5bd ("kernel/fork: always deny write access to current > MM exe_file") added a semaphore up/down cycle to synchronize the state > of exe_file against fork, defeating the point of the original change. Agreed, > Signed-off-by: Mateusz Guzik > --- > fs/exec.c | 4 ++-- > kernel/fork.c | 22 +++++++++------------- > 2 files changed, 11 insertions(+), 15 deletions(-) Acked-by: Oleg Nesterov