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 X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6EDEC83000 for ; Wed, 29 Apr 2020 18:52:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9751620661 for ; Wed, 29 Apr 2020 18:52:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="pYfMbweJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727025AbgD2SwL (ORCPT ); Wed, 29 Apr 2020 14:52:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46260 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726423AbgD2SwL (ORCPT ); Wed, 29 Apr 2020 14:52:11 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4507BC03C1AE for ; Wed, 29 Apr 2020 11:52:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=FreQTZyNiQbmio5nHGLGF2May2I7BgbfYH3zJe2eCY8=; b=pYfMbweJoOSbYYIWpbnXDRvmNL b9IF6Znq+xvAKwoZPExCr3Vm7SxR6MjaUkA6TTJL8vMPu+FzYO5tyy9/EMNu4cgTfZVFZzpydqnF6 tRlB1QbjXxKmOgsPYAyp9Igsfhj8QL5ridRkiaP3M4FxK/LzarDHdCrLcy6wy3TAcMR4bpvhmw1QA uBbHEoaT6VjEgEPu4Kk5WC8lubBpMDACKQT9pRGLwDXShO3f0GJrhXPLBubiemPuqUh6kV5R2HEkk kTOwjA6Uu5NXlON5rogOBnhp+equjWUogDI5Ley9TFAIMnWUCtFhrePKXQl4TBfAnmUofC2tN5y+m LKiKwVpQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jTroJ-0008Qq-9B; Wed, 29 Apr 2020 18:51:55 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id EDF6D300130; Wed, 29 Apr 2020 20:51:51 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E00EE20BD8FF7; Wed, 29 Apr 2020 20:51:51 +0200 (CEST) Date: Wed, 29 Apr 2020 20:51:51 +0200 From: Peter Zijlstra To: Mathieu Desnoyers Cc: rostedt , Joerg Roedel , linux-kernel , Ingo Molnar , Thomas Gleixner , Borislav Petkov , Andrew Morton , Shile Zhang , Andy Lutomirski , "Rafael J. Wysocki" , Dave Hansen , Tzvetomir Stoyanov Subject: Re: [RFC][PATCH] x86/mm: Sync all vmalloc mappings before text_poke() Message-ID: <20200429185151.GO13592@hirez.programming.kicks-ass.net> References: <20200429054857.66e8e333@oasis.local.home> <20200429105941.GQ30814@suse.de> <20200429082854.6e1796b5@oasis.local.home> <20200429100731.201312a9@gandalf.local.home> <20200429161747.GS30814@suse.de> <20200429162026.GT30814@suse.de> <20200429125245.5a804f62@gandalf.local.home> <951556503.76104.1588181386082.JavaMail.zimbra@efficios.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <951556503.76104.1588181386082.JavaMail.zimbra@efficios.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > Basically, it's a big bitmask, where each bit represents a possible process > > id (can be 2 gigs if we allow all positive ints!). > > I think you mean 2 giga-bit, for 256MB worth of memory, right ? > > And AFAIU the PID_MAX_LIMIT is at a maximum of 4 million PIDs in > include/linux/threads.h, which means 512MB worth of memory for a > bitmask. PID space is limited to 30 bits per FUTEX_TID_MASK, still, stupid large :-)