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 EAFFDE7717F for ; Thu, 12 Dec 2024 17:22:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4E0F46B007B; Thu, 12 Dec 2024 12:22:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 491456B0082; Thu, 12 Dec 2024 12:22:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 359CF6B0085; Thu, 12 Dec 2024 12:22:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 17EE76B007B for ; Thu, 12 Dec 2024 12:22:31 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id BD2F114045E for ; Thu, 12 Dec 2024 17:22:30 +0000 (UTC) X-FDA: 82886975808.02.E58CCD2 Received: from mail-qt1-f180.google.com (mail-qt1-f180.google.com [209.85.160.180]) by imf08.hostedemail.com (Postfix) with ESMTP id 5525516000E for ; Thu, 12 Dec 2024 17:22:12 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=DaiYDiog; spf=pass (imf08.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.160.180 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1734024132; 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=ItVZ115MBy00UtnwKK7ISqvPf5/M4tPNwbj4rk9A9Wk=; b=WRFXxYbfAhr29NCgwQ81rQOpw/0mpBQDTuO6VCkWTxhKF2pQqDhI3L5Us8H3eNu7HoNkYq vQ5121i7i+3uQwaLhVZNmZs3xDhjYi2/yvuuOKSY1TIHaK5LYzmYuLB22Bnq2D04nudelN jSw6YKYpso49hGnBEiTfVKSg16O16Jo= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=DaiYDiog; spf=pass (imf08.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.160.180 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1734024132; a=rsa-sha256; cv=none; b=fvIF+JUA7GkvZ5eqKkc3SFsdooriVE2P/jUCGq9Jiunb51DyjErghYPsUxicM6cnKvFyB5 MHVtx9sAFeADRe8mttYgErRQkxCividhtdCp9ZQw+XeaN2n9PBrCArIZh+A4gZSRQ51cQp yglXXBjUUmuyUZOAJT5pRsNnWB3kOdc= Received: by mail-qt1-f180.google.com with SMTP id d75a77b69052e-467a37a2a53so471231cf.2 for ; Thu, 12 Dec 2024 09:22:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20230601.gappssmtp.com; s=20230601; t=1734024147; x=1734628947; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=ItVZ115MBy00UtnwKK7ISqvPf5/M4tPNwbj4rk9A9Wk=; b=DaiYDiogEywvtxnwPUgvH3r0WJlAbvBVgtwmWGYyAHjrFJh/RpVEBUIMupakXSyivi 3ObruAHojdLVpR4X5c7DtKIAHKxnX/a9OpbFtSGueUbMBPYumhOr3nn7nM9HTOxw9EPl tQBEkd6gjm7nb/8ewXOd97PduRpUCfZz/7qcRsX/suGzTfGbaje1WN4vY24R5J7uuX0E 0uS7K89O3MAGtUUAYvJDIPOJXpjPCI+zvb8mR8OM70xc1y5fiHw3+s9wx4OsyccOLy3U F0QoHEHOtPqBnmf0AX4e9v5UmiI3DY+do/OINN8Wx5D0OghDV79fp+N6j0077kTbigA7 ppRA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1734024147; x=1734628947; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=ItVZ115MBy00UtnwKK7ISqvPf5/M4tPNwbj4rk9A9Wk=; b=thZ6GfuJZUPF8HYBPNNTLwSmUOYHmP1spTFn1dbeQ+CxxSUU7345UruBxwbSEIn0JJ t48ZWoa1Ge+DtHzSvPEtaq70v6Kdb/vdky9tKVlt7n5ZuCqrsX0aIwEAICyfZooiITQm T9TfzdsmwR8VbPnuD0ZmUXV6TxYRc9ry0B3KjtNHxggUutL/7jzDYgEXG11loChXLKnW Smy6vkCJD29Qwxj4s5/+ufiVSAZAR+0c+IIAPJ5c4SF8X6VpCTFqxhrIpi/18xgMnyJb gqpOIxhPj1XoO/k0ncircyUzntY38+A+Cuj+wpvqnqQm/WbSYPAyL4Jh5V/yNcHzHBj2 vldg== X-Forwarded-Encrypted: i=1; AJvYcCVAhPHMSHIL6Vvsmg44Yl0kbS30B+bsdyqUSmsGK8CSJWsxu8UnL+g3Qj5FWLZgsQO0L1B4LwAeCw==@kvack.org X-Gm-Message-State: AOJu0YxNDQnQbH0YPL4H+2Eb0hm21z0uAppn1sgp3dju7/87xlAZg5pb zSooRPRrtr5tvN7K/Ac4oyUBPKw4+0/pZNaaXgSCjl3jPTIdXF4iUMKr4yujjLsXcoMOIClFxsx Y X-Gm-Gg: ASbGncvZNJ7bOu71EtbHNEai2BovihGgpWdkcFAwK3D3DGHDljgpXGfmXsVDugaVPEu UsAk1KYKTo7lbYmeNVCcHh/5d25b7IQl6f0AIqVQg3PTZtFR+jZw/xjXOCpzJn3isee00Sw6QOe u3KJaf3BGWCgZ6q6WAabIYE7YWaJbyPE1rHZd4HeSyO0JChBW2sKMgpNvzrBC9z1/hhuHT3Vn8G DvkcXE6v1pEqR0fJnwlkjflHfa2RlE4OdOLwu7Z+Z6ZgZbeZ50h9bg= X-Google-Smtp-Source: AGHT+IFwlTozGuchS7xOSbyLPAV7MX4qrVeVLcoFK+ZdGoUf0iC8iJIQmZdAV5+VIAr1Q+4xDj16IA== X-Received: by 2002:a05:6214:b69:b0:6d8:a148:9ac9 with SMTP id 6a1803df08f44-6db0f80e72cmr14012946d6.30.1734024147597; Thu, 12 Dec 2024 09:22:27 -0800 (PST) Received: from localhost ([2603:7000:c01:2716:97cf:7b55:44af:acd6]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6d8da9feab9sm83721546d6.71.2024.12.12.09.22.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Dec 2024 09:22:26 -0800 (PST) Date: Thu, 12 Dec 2024 09:22:18 -0800 From: Johannes Weiner To: Usama Arif Cc: david@redhat.com, akpm@linux-foundation.org, linux-mm@kvack.org, riel@surriel.com, shakeel.butt@linux.dev, roman.gushchin@linux.dev, yuzhao@google.com, npache@redhat.com, baohua@kernel.org, ryan.roberts@arm.com, rppt@kernel.org, willy@infradead.org, cerasuolodomenico@gmail.com, ryncsn@gmail.com, corbet@lwn.net, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH] mm: convert partially_mapped set/clear operations to be atomic Message-ID: <20241212172218.GA19302@cmpxchg.org> References: <20241212135447.3530047-1-usamaarif642@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241212135447.3530047-1-usamaarif642@gmail.com> X-Rspamd-Server: rspam05 X-Stat-Signature: dutdgab678jmti43t3g5mg74bj3k9hjx X-Rspamd-Queue-Id: 5525516000E X-Rspam-User: X-HE-Tag: 1734024132-683121 X-HE-Meta: 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 5KEnL9uL 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.195045, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Dec 12, 2024 at 01:54:47PM +0000, Usama Arif wrote: > Other page flags in the 2nd page, like PG_hwpoison and > PG_anon_exclusive can get modified concurrently. Hence, > partially_mapped flags need to be changed atomically. Can you please include a description of possible consequences if this happens? I realize this was spotted through review, but it's still important to break down how this might impact users. > Fixes: 8422acdc97ed ("mm: introduce a pageflag for partially mapped folios") This is in an alreaady released kernel. Do we need this: Cc: stable@vger.kernel.org > Reported-by: David Hildenbrand Link: https://lore.kernel.org/all/e53b04ad-1827-43a2-a1ab-864c7efecf6e@redhat.com/ > Signed-off-by: Usama Arif Acked-by: Johannes Weiner