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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 CCA92C433E4 for ; Tue, 14 Jul 2020 18:49:44 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9387422AB9 for ; Tue, 14 Jul 2020 18:49:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="VvlDJH5C" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9387422AB9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1EED66B0002; Tue, 14 Jul 2020 14:49:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 19EF26B0005; Tue, 14 Jul 2020 14:49:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 08CEA6B0006; Tue, 14 Jul 2020 14:49:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0080.hostedemail.com [216.40.44.80]) by kanga.kvack.org (Postfix) with ESMTP id E446F6B0002 for ; Tue, 14 Jul 2020 14:49:43 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 448E62DFA for ; Tue, 14 Jul 2020 18:49:43 +0000 (UTC) X-FDA: 77037570246.29.earth55_28156a226ef3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin29.hostedemail.com (Postfix) with ESMTP id 6510218086E4B for ; Tue, 14 Jul 2020 18:49:42 +0000 (UTC) X-HE-Tag: earth55_28156a226ef3 X-Filterd-Recvd-Size: 5332 Received: from mail-lf1-f66.google.com (mail-lf1-f66.google.com [209.85.167.66]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Tue, 14 Jul 2020 18:49:41 +0000 (UTC) Received: by mail-lf1-f66.google.com with SMTP id o4so12916991lfi.7 for ; Tue, 14 Jul 2020 11:49:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Alox4jKEMRaA950HZ1waP0+wedXfzVsNihjzfohVQYc=; b=VvlDJH5CSlxwkIB6dqeYM9fELFt2NoQrAo8WwW52hkqyP+QEgrAcfi37PxvMFQ3jXz exscy1cS5CvqO0N4kUSCglH47nIFT7m+TmAko7nxgzLwvs9rvLlklibVS3y9Lb+KsOEb 7GJJwIeCsAlMivcZbPoiCqejNh8PNrAxOIO3I= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Alox4jKEMRaA950HZ1waP0+wedXfzVsNihjzfohVQYc=; b=QWTr7aRN1458AsPS4JNb42MW5YvAHmAPQiZWdzmgAqUok9fueefv4ylTdaiWf+U/3p zIxVQCIEjGkp+eU25zpPZ8xpLqdrgIxF+C/CkMEWYF93G2oGYl88bCZ1vWXK5DynI1s2 LOEYST2Rdx3itsJJGeSCwZgaY503rE8kYyQzFDpE4ox+NTb4PxheMvuLA0SUxpxFgQtM PTMsaFj9OV4RXsLUNk98+cBgiIAI/yO6kv01uhSySg0MhUSXXzwpa4ZfOTRB+CBREvVm U8Hk8nffFY19Ei/G8jDDJBtq4j/fHGld3tHHaQ+m5XGAKA4I19PDTrsoPWkeG8+VGDn+ zWUw== X-Gm-Message-State: AOAM530SGsHPIUDngJHlsAzIP/9Zj+2oNwQ/klwiRmJxYvNPC2rKfKD/ P5ACk+TEmFFq8kDHmvTHSTkg5/VlrLQ= X-Google-Smtp-Source: ABdhPJxWngul0CZ2B5jRh7deJwLU70pMf+daVmk3JYFkZCPWV5a/gvrU69pV1ZHBYWS2ENcI/fVSHQ== X-Received: by 2002:ac2:5a01:: with SMTP id q1mr2842732lfn.182.1594752578779; Tue, 14 Jul 2020 11:49:38 -0700 (PDT) Received: from mail-lj1-f178.google.com (mail-lj1-f178.google.com. [209.85.208.178]) by smtp.gmail.com with ESMTPSA id s8sm4792793ljh.74.2020.07.14.11.49.36 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Jul 2020 11:49:37 -0700 (PDT) Received: by mail-lj1-f178.google.com with SMTP id q4so24853222lji.2 for ; Tue, 14 Jul 2020 11:49:36 -0700 (PDT) X-Received: by 2002:a2e:86c4:: with SMTP id n4mr3097947ljj.312.1594752576542; Tue, 14 Jul 2020 11:49:36 -0700 (PDT) MIME-Version: 1.0 References: <20200712215041.GA3644504@google.com> <20200714073306.kq4zikkphqje2yzb@box> <20200714160843.GA1685150@google.com> In-Reply-To: From: Linus Torvalds Date: Tue, 14 Jul 2020 11:49:20 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: WARNING: at mm/mremap.c:211 move_page_tables in i386 To: Joel Fernandes Cc: "Kirill A. Shutemov" , Naresh Kamboju , linux- stable , open list , linux-mm , Arnd Bergmann , Andrew Morton , Roman Gushchin , Michal Hocko , lkft-triage@lists.linaro.org, Chris Down , Michel Lespinasse , Fan Yang , Brian Geffon , Anshuman Khandual , Will Deacon , Catalin Marinas , pugaowei@gmail.com, Jerome Glisse , Greg Kroah-Hartman , Mel Gorman , Hugh Dickins , Al Viro , Tejun Heo , Sasha Levin Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 6510218086E4B X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 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 Tue, Jul 14, 2020 at 11:12 AM Joel Fernandes wrote: > > I think you misunderstood me. I was not advocating breaking the stack > movement code or breaking stack randomization, I was going to try to > see if I could keep that working while not having to do an overlapping > move. I'm not really seeing how you'd do that with a big stack that gets close to the stack ulimit. Except by avoiding randomization. But the existing randomization may be so bad that it doesn't much matter. And I do think we limit the execve stack to a reasonably small fraction of the whole ulimit. So worth exploring, I guess. The current code with "align_stack" doing randomization could also do with a lot of clarifications. The code is odd. Linus