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 1BBD0EEEC0E for ; Fri, 13 Sep 2024 05:47:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2EC998D0003; Fri, 13 Sep 2024 01:47:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 29BE78D0001; Fri, 13 Sep 2024 01:47:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 13DC48D0003; Fri, 13 Sep 2024 01:47:25 -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 E9B208D0001 for ; Fri, 13 Sep 2024 01:47:24 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 6CCED1416D1 for ; Fri, 13 Sep 2024 05:47:24 +0000 (UTC) X-FDA: 82558632408.27.B5F36A1 Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) by imf10.hostedemail.com (Postfix) with ESMTP id 25C48C000B for ; Fri, 13 Sep 2024 05:47:21 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=csgroup.eu; spf=pass (imf10.hostedemail.com: domain of christophe.leroy@csgroup.eu designates 93.17.235.10 as permitted sender) smtp.mailfrom=christophe.leroy@csgroup.eu ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1726206325; 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; bh=7YZbvbcSt9mAXuInSQIr6d+PI1iIjPNJ19A2irz55kA=; b=F71lFqZ7gpBTJQRfjn3wNxx4mx7O4Ump8BNTxMBPGLJN6BTsOzbVtB4q7yiCORsrpfS7VC eEaLP8w4rHQcAUsydhDGUhmjsuIrbwUxo4NBOW8j/7iGCpw30CmCrFn9CTeNBJwxh+vgQt iQfzMYhQzRtc6IQavUa4QS+JrvJDCqo= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1726206325; a=rsa-sha256; cv=none; b=HgxWT1NS+7IkbpxOEzn9C0fmXi0JJXGRP6JyQ11hZuTN8bjvhQV9LFIBd3PtaL/btX16D0 C0Xb5JPkIe61UXzuPPnalVenrFwYOkxa5kUu0BoOrkkmK2olSK5i3028nUzV6TSO0NFqYZ XEPfbf6E8HXp4+GsTms0aof242pXdPg= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=csgroup.eu; spf=pass (imf10.hostedemail.com: domain of christophe.leroy@csgroup.eu designates 93.17.235.10 as permitted sender) smtp.mailfrom=christophe.leroy@csgroup.eu Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4X4jxg6vMMz9sxD; Fri, 13 Sep 2024 07:47:19 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rcETtnnNavE7; Fri, 13 Sep 2024 07:47:19 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4X4jxg5s39z9sjv; Fri, 13 Sep 2024 07:47:19 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id B48CF8B77A; Fri, 13 Sep 2024 07:47:19 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id BrEQGrKMhBAg; Fri, 13 Sep 2024 07:47:19 +0200 (CEST) Received: from [192.168.233.70] (unknown [192.168.233.70]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 458908B766; Fri, 13 Sep 2024 07:47:18 +0200 (CEST) Message-ID: Date: Fri, 13 Sep 2024 07:47:17 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [linus:master] [mseal] 8be7258aad: stress-ng.pagemove.page_remaps_per_sec -4.4% regression To: Michael Ellerman , Linus Torvalds , Nicholas Piggin Cc: Jeff Xu , Pedro Falcato , kernel test robot , Jeff Xu , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, Andrew Morton , Kees Cook , "Liam R. Howlett" , Dave Hansen , Greg Kroah-Hartman , Guenter Roeck , Jann Horn , Jonathan Corbet , Jorge Lucangeli Obes , Matthew Wilcox , Muhammad Usama Anjum , =?UTF-8?Q?Stephen_R=C3=B6ttger?= , Suren Baghdasaryan , Amer Al Shanawany , Javier Carrasco , Shuah Khan , linux-api@vger.kernel.org, linux-mm@kvack.org, ying.huang@intel.com, feng.tang@intel.com, fengwei.yin@intel.com References: <202408041602.caa0372-oliver.sang@intel.com> <87r0b2if4t.fsf@mail.lhotse> Content-Language: fr-FR From: Christophe Leroy In-Reply-To: <87r0b2if4t.fsf@mail.lhotse> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 25C48C000B X-Stat-Signature: uccy15xf86gun1i7s47ebkmc3ry43zx8 X-Rspam-User: X-HE-Tag: 1726206441-367393 X-HE-Meta: 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 A5qq4k0S 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 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: Le 06/08/2024 à 04:01, Michael Ellerman a écrit : > Linus Torvalds writes: >> On Mon, 5 Aug 2024 at 16:25, Nicholas Piggin wrote: >>> >>> Can userspace on other archs not unmap their vdsos? >> >> I think they can, and nobody cares. The "context.vdso" value stays at >> some stale value, and anybody who tries to use it will just fail. >> >> So what makes powerpc special is not "you can unmap the vdso", but >> "powerpc cares". >> >> I just don't quite know _why_ powerpc cares. > > AFAIK for CRIU the problem is signal delivery: > > arch/powerpc/kernel/signal_64.c: > > int handle_rt_signal64(struct ksignal *ksig, sigset_t *set, > struct task_struct *tsk) > { > ... > /* Set up to return from userspace. */ > if (tsk->mm->context.vdso) { > regs_set_return_ip(regs, VDSO64_SYMBOL(tsk->mm->context.vdso, sigtramp_rt64)); > > > ie. if the VDSO is moved but mm->context.vdso is not updated, signal > delivery will crash in userspace. > > x86-64 always uses SA_RESTORER, and arm64 & s390 can use SA_RESTORER, so > I think CRIU uses that to avoid problems with signal delivery when the > VDSO is moved. > > riscv doesn't support SA_RESTORER but I guess CRIU doesn't support riscv > yet so it's not become a problem. > > There was a patch to support SA_RESTORER on powerpc, but I balked at > merging it because I couldn't find anyone on the glibc side to say > whether they wanted it or not. I guess I should have just merged it. The patch is at https://patchwork.ozlabs.org/project/linuxppc-dev/patch/afe50d1db63a10fde9547ea08fe1fa68b0638aba.1624618157.git.christophe.leroy@csgroup.eu/ It still applies cleanly. Christophe > > There was an attempt to unify all the vdso stuff and handle the > VDSO mremap case in generic code: > > https://lore.kernel.org/lkml/20210611180242.711399-17-dima@arista.com/ > > But I think that series got a bit big and complicated and Dmitry had to > move on to other things. > > cheers