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 BD050C6FD18 for ; Tue, 18 Apr 2023 21:21:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5D0968E0005; Tue, 18 Apr 2023 17:21:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 55923900002; Tue, 18 Apr 2023 17:21:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3F9818E0005; Tue, 18 Apr 2023 17:21:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 30884900002 for ; Tue, 18 Apr 2023 17:21:10 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 02EE11A032D for ; Tue, 18 Apr 2023 21:21:09 +0000 (UTC) X-FDA: 80695782300.02.60D5964 Received: from mail-yw1-f170.google.com (mail-yw1-f170.google.com [209.85.128.170]) by imf08.hostedemail.com (Postfix) with ESMTP id 35C5F160007 for ; Tue, 18 Apr 2023 21:21:08 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=rIRTptJw; spf=pass (imf08.hostedemail.com: domain of hughd@google.com designates 209.85.128.170 as permitted sender) smtp.mailfrom=hughd@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1681852868; 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=qWdLrM8P5tKlvuJeK/CWoUbY/57OR2hY93j5YcDXvNw=; b=y4K0ZIgcQZZ4M9HdQQuDhuV083NMTdGUoQYNXVGOMePGhTOOFAor+tXmPP6FjvNB3ehfIx K0kPNbmZLTibrg1lNxsGNpWC9Z7vcnNFS2X5In8dw9G91DN9/U9BojYW4KgXiHrLxjIKXV Vb2hrIcMLWZpa4qAI9MHs8OXtdOl+24= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=rIRTptJw; spf=pass (imf08.hostedemail.com: domain of hughd@google.com designates 209.85.128.170 as permitted sender) smtp.mailfrom=hughd@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1681852868; a=rsa-sha256; cv=none; b=fVGJw1iI0nvw6Qm1xfeboupfm+fm2JUjdnVmDCF0hgAAtsxGx2G0hRUeAf8DSXg396TfmE jZxzDl3KizfJE5kyFO/CPEHEQul+XyzU0Or7ahKa6XHXFte7DRhv3mz0geUqz/Xuca8EJG xoEgHDg33nzVUuzv+SgO/HDESkUTCwQ= Received: by mail-yw1-f170.google.com with SMTP id 00721157ae682-552ae3e2cbeso103608117b3.13 for ; Tue, 18 Apr 2023 14:21:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1681852867; x=1684444867; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=qWdLrM8P5tKlvuJeK/CWoUbY/57OR2hY93j5YcDXvNw=; b=rIRTptJwMR9RNS5QlyMl2+kc/TA94WPxxo3f17+iyobEdC0e4rGfCX48D58F9wRJ6F si1gyr55NBY4UOviXN1eiHhiQaxYaHuCE5ioCUOVyPjoa+XkSyUu9t8L8sKz7wWAYekm zUYRulerwJQcUyMI4D+11I2DEmWz4gCwDJOkEc7MKuDG+DfQ7y0+dsiRfgCNNXmsyJKN FfZEw0TtwsR66InOJ0KmbpMkRLVFOFAg4qhbyP4RBveRx3xAkk8RGmBURRUscz64s/1u B2dmhngysNOAXtqHSsnNtwNy33v9E1TaHdNjoCQdIFR/tZbAX3SUBDDThd7CqDADtK7e iavg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681852867; x=1684444867; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=qWdLrM8P5tKlvuJeK/CWoUbY/57OR2hY93j5YcDXvNw=; b=HAfgLfzqwnof3i/4DDftEVuSZ1UICbErWGe184AkRex6/am6Zj0AecwPLb0gToY4Oq wy2VscvMMn5m5rSDbc8r2Lnfm0WW9W7HggDC704iZ+rVuMqdlkaJzA5hWUu3tdvTWQTm M/W0V84lBiFrkkaoSwb6CddHWWChMDb4d/WsyKNVcpkXF/96RYagkLgMLAnmpUTgtK4E sEZylaZrWRXcGR8wzMz2r/SlTJi2523XkJCOQGgMJT4d9lIbY3kBJp3Qmyn8xHzyJ4Yd P4I8QVSKG+14qnNP3vfkXOdt+Ox1omawHllo7As+qQNLcsSoicnO9KLaU2/fOasCVMb4 KdKw== X-Gm-Message-State: AAQBX9dtjQqZCIdV7HfXM7Zw8HEYkLx6tQEivBFmpAieD53WNhommyFi R8yrp9JWFI/tZA35qBkfI9xEOA== X-Google-Smtp-Source: AKy350aPT69etndT9Y5DXnIKWAPOkeuFizCReXExgc8GViiHUiiYdlDYCcOditcCtgaKdDHGXYA48Q== X-Received: by 2002:a0d:d597:0:b0:54e:f0d1:e3e5 with SMTP id x145-20020a0dd597000000b0054ef0d1e3e5mr1346873ywd.24.1681852867289; Tue, 18 Apr 2023 14:21:07 -0700 (PDT) Received: from ripple.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id l15-20020a81700f000000b0054629ed8300sm4054543ywc.80.2023.04.18.14.21.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Apr 2023 14:21:06 -0700 (PDT) Date: Tue, 18 Apr 2023 14:20:55 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Luis Chamberlain cc: Hugh Dickins , akpm@linux-foundation.org, willy@infradead.org, brauner@kernel.org, linux-mm@kvack.org, p.raghav@samsung.com, da.gomez@samsung.com, a.manzanares@samsung.com, dave@stgolabs.net, yosryahmed@google.com, keescook@chromium.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, David Hildenbrand Subject: Re: [PATCH v2 4/6] shmem: skip page split if we're not reclaiming In-Reply-To: Message-ID: <8afe1f7f-31a2-4fc0-1fbd-f9ba8a116fe3@google.com> References: <20230309230545.2930737-1-mcgrof@kernel.org> <20230309230545.2930737-5-mcgrof@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 35C5F160007 X-Rspam-User: X-Stat-Signature: bh79mpzkckt1fzgnok581kc15qgnx19t X-HE-Tag: 1681852868-562844 X-HE-Meta: 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 Ai3FLF+R RkuuW8ogi9rRg0Uq68SvKJz0qA92CyThUHSszyDS/JX+RhsShhHmJaTXWJ1EXr2odo3VdBlYEkSqYkwRWX3u8kqIiGtT1AaIYyrIwLZOpUWqXbZG5wv0p21Z+Oyg4uqNnTRyZCAzEWfDAfpQh7/FyI7eM5mMLVzs3KQH/zM+YqsX5WRqMS2pyz5L1THseCA+afxtCu0iaEqZULIHbOneqJ/CRq91vQu2l/DArUhJ9f1hgHJDZLpX1Sa3ShFacitFpYNftbYjdPDpKb0gnLPmPygPG+pJ8GyEjI5xs4b/TuWhV09ay22OER4mVuQ0EGdoariUzMiptyz+HFeQJZDoncJ5enrQKZczviTreIjBV1GLiDgvjecWUGsLB+fVNQfulkH8WmfAg87k73l7GLHY3rv2nIg== 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, 18 Apr 2023, Luis Chamberlain wrote: > On Mon, Apr 17, 2023 at 09:41:41PM -0700, Hugh Dickins wrote: > > On Thu, 9 Mar 2023, Luis Chamberlain wrote: > > > > > + if (WARN_ON_ONCE(info->flags & VM_LOCKED)) > > > + goto redirty; > > > > Well, okay, I don't mind that. But shall we take bets on how soon syzbot > > (hope it's not watching) will try flipping SHM_LOCK on while swapping out > > pages from a SHM segment, and hit that warning? Perhaps I'm wrong, but I > > don't think any serialization prevents that. > > I though that may be the case. Would such serialization be welcomed? Absolutely not! We don't insert slowdowns just to avoid warnings, unless the warning is of something that really matters. This one does not matter, the situation is correctly handled, so the warning would be better reverted. Though I personally don't mind you leaving it in until the first report of it arrives. Hugh