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[209.85.208.179]) by smtp.gmail.com with ESMTPSA id q13sm737764lfb.55.2020.07.15.14.51.49 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Jul 2020 14:51:49 -0700 (PDT) Received: by mail-lj1-f179.google.com with SMTP id h22so4423444lji.9 for ; Wed, 15 Jul 2020 14:51:49 -0700 (PDT) X-Received: by 2002:a2e:9b42:: with SMTP id o2mr509216ljj.102.1594849908727; Wed, 15 Jul 2020 14:51:48 -0700 (PDT) MIME-Version: 1.0 References: <20200715135011.42743-1-kirill.shutemov@linux.intel.com> <20200715205508.3rzrkhulruzpy6iv@box> In-Reply-To: From: Linus Torvalds Date: Wed, 15 Jul 2020 14:51:32 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCHv2] mm: Fix warning in move_normal_pmd() To: "Kirill A. Shutemov" Cc: "Kirill A. Shutemov" , Andrew Morton , Linux-MM , Linux Kernel Mailing List , Naresh Kamboju , Joel Fernandes , William Kucharski Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 18E3B180442C3 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jul 15, 2020 at 2:35 PM Linus Torvalds wrote: > > The stack relocation only moves down. .. and that may not be true on a grow-up stack. Christ, that code is hard to read. But I think Kirill is right, and I'm wrong. So that "try to expand" code is only ok when non-overlapping, or when moving down. Naresh - from a testing standpoint, that doesn't make any difference: I'd still like you to test on x86. We always shift the stack down there. Linus