From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id EDFCD606A31B for ; Tue, 27 Oct 2026 08:22:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=XcnbEhAI Received: by kanga.kvack.org (Postfix) id 080CB6B061A; Tue, 27 Oct 2026 04:22:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 00B1B6B061B; Tue, 27 Oct 2026 04:22:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E14A36B061C; Tue, 27 Oct 2026 04:22:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id BB32B6B061A for ; Tue, 27 Oct 2026 04:22:19 -0400 (EDT) Received: from smtpin30.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 3F9AB40902 for ; Tue, 27 Oct 2026 08:22:19 +0000 (UTC) X-FDA: 85367713998.30.0599BE8 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf03.hostedemail.com (Postfix) with ESMTP id A6F7020009 for ; Tue, 27 Oct 2026 08:22:17 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=XcnbEhAI; spf=pass (imf03.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793089337; 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=F88x0w6RcEa+c5taIt0Fmt+oPbV+qXUJjPjIECkCifM=; b=3xr9/2kdXRaqFvTP/8vMq3lQQ/3n1y1RQO/v7oKWxDlblj1Obe5D6tYTSDuPF5u3Lo7sbK LpIBLQ7rkA0V+3lC8WZssEiL8TFX8N3OuaAgRAzxCb9GUkim48hM7a1IBR92SLE8CidHpp Cmjf/f9ZKx3EB1dexwWd2y4Gd2I39+8= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=XcnbEhAI; spf=pass (imf03.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793089337; b=gb0IyIRI7KbJlNeFBSwiUHGw2T2mDhSmShJT/AO+ZDdKAGgrdnG+4c11EwKnNckw9ItZWg kkJQXQ1Zixm096QqHmeyZJ1YT8ygt+71hxHmNo0+IIX9W7c2t5T3X+3B9DqSQpXZUzjwMC gPc+zGl7wK9BYFu5jxUQp76fXBv2lts= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 2FB0860052; Tue, 27 Oct 2026 08:22:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 132EB1F01825; Tue, 27 Oct 2026 08:21:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793089336; bh=F88x0w6RcEa+c5taIt0Fmt+oPbV+qXUJjPjIECkCifM=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=XcnbEhAIT53D3Hun+lr/E6g8U6iRmEJKDft/fCMNmTrAnwk0hAOsyjOokbVPvXEp4 /DPpT5Su9B/w3gWyP9HIp6tCbM8SpfFZQEHmk9xZRAFv8vtovKBHP6oMqM2laor/ar P09hpU7MLdF9KtuqzyyOT3LFejOV+LPLAbIgOliERfOsJ89eZuESqQurxPzGdarj2T 8EyrmmZ5UZbvTI7dzlnWbVesHv53x07RfUr1UgzVZx1w/Da9SXe+VMmXlfYIiXPrGF gCrBiBDheLyK5D4iKWh7VKsJm6UWGTipezUjwklfkuNFfwKK/QHJ4IhVCDB+Sy/wHO TpCkfYmmCp5fQ== Date: Tue, 27 Oct 2026 10:21:54 +0200 From: Mike Rapoport To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 25/46] mm/userfaultfd: wake waiters when registration modes are removed Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-25-6f74bec9a5bb@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261027-fixes_core-v1-25-6f74bec9a5bb@kernel.org> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A6F7020009 X-Stat-Signature: fmbcmzncm7r5eu55pn8c7ku5kdayycp1 X-Rspam-User: X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-HE-Tag: 1793089337-265433 X-HE-Meta: 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 nR2kitH/ XzPytAPFZco9tY6+LhltCzgd1TmV0nHG9yhfvSkK5sMAXoXCIc9ixuEoKVc/zMXufC0S6e+tQgkiJcFw2mo9se5P73wfafWkaOOt8aWU+y2bCZaivxY4s2Kr0Sap28obiUJ81OtGFbe6WXPdK6L7nPdaz1gpMmi7gaoVqo9ae8kzlk7UacWXBmL2QbKb1zPLRy9eHv7bmoMqZhsbBIZg1n9qbjmQBcXClsTlIr0QjSZXnnsiY/KoIGAeaUlZ67PhUzl7Ea+jmTNnnyhm+kklJmdIMFZ2CV6rSv73KDADrr5H+l9tF/uEFIkrwIyO8KPMwCftbTyYh5XdB2TkMMW6oFYfNmvaQRMoHeUVv Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Oct 27, 2026 at 12:17:45AM +0100, David Hildenbrand (Arm) wrote: > UFFDIO_REGISTER can replace MISSING or MINOR tracking without waking > faults that are already queued. For example, switching an anonymous > range from MISSING to WP leaves a missing-fault waiter asleep until > userspace explicitly wakes it. > > When a registration change removes a UFFD mode, wake waiters in the > affected interval after updating the VMA. The VMA is write-locked at > this point, so no new faults can queue under the old modes and woken > threads cannot retry until mmap_write_unlock(). Waiters for retained > modes in the same interval may also wake and refault. > > The hang reproduces for MISSING-to-WP and MINOR-to-MISSING transitions, > with both read and unread fault events. > > Fixes: 63b2d4174c4a ("userfaultfd: wp: add the writeprotect API to userfaultfd ioctl") > Cc: stable@vger.kernel.org > Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Mike Rapoport (Microsoft) > --- > mm/userfaultfd.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) -- Sincerely yours, Mike.