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 61E0C606A31F for ; Tue, 27 Oct 2026 08:36:57 +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=YgWQ0jUy Received: by kanga.kvack.org (Postfix) id 13AD56B0618; Tue, 27 Oct 2026 04:36:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 112BE6B0623; Tue, 27 Oct 2026 04:36:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 04FEA6B0625; Tue, 27 Oct 2026 04:36:55 -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 D11316B0618 for ; Tue, 27 Oct 2026 04:36:55 -0400 (EDT) Received: from smtpin24.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 595D41A02FA for ; Tue, 27 Oct 2026 08:36:55 +0000 (UTC) X-FDA: 85367750790.24.1B9977B Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf21.hostedemail.com (Postfix) with ESMTP id C71641C0005 for ; Tue, 27 Oct 2026 08:36:53 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=YgWQ0jUy; spf=pass (imf21.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@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=1793090213; 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=yYgcjxrZzXoy0psYU0Nq+QxW34HHCYEZSvr+g4Xkf3Q=; b=ehaTrv85rcs2fM1QWYeJcu+5BcT4Zi7Gp0RLlFLg063immEaCZkgliZXWcr2mdHH5Or14B ssHZQB/4Bcs2Zpt2QAxplGqHqP5vJmno9GJGmIKZBqzQE0HWE4u7lUSONWQH8575hg3SuJ pA+XiBYD9emOdGW4jWgrS6j3T5xlJzw= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=YgWQ0jUy; spf=pass (imf21.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@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=1793090213; b=Th9UHLECpTcE/oAt1xE0NFXmpBnG3HQSaFwiOsfnJs6NB5mqhJq0NBK5pi7hqpiCFCv/NI fX77QjHfOHHUr4lR+xerUQB6c3UXhyXrJEGZDbCtJyKIRmasa4Kae2Kk8g6YOhdWCIayJP /tBs+W2mK+QmuPwyBeXSw06x+RXhTAE= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 4B6C6601F9; Tue, 27 Oct 2026 08:36:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0202A1F01825; Tue, 27 Oct 2026 08:36:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793090213; bh=yYgcjxrZzXoy0psYU0Nq+QxW34HHCYEZSvr+g4Xkf3Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=YgWQ0jUy2R3Rh6tVUq1cYOMph9r06iXsVVDLcV7MttnPuaU1a16q5fg+QaCk7f+Fx FzVMQCYd/p+MkpgpnFyBzCzl+fi3rnW0pIlK1fRrVDOkrsTCamrF3lIKcsPE77OK+Q GIcJKTG5KNfSBGz+lX+edsIgMQTXvFzfUt5kzxtbIx9RH8l3e/D3N5JbaEWymZs/AM k9m2KnjFXcgH69AYMz8pQx4Dw81BFFnZ5uku8faOD0mwALYfuFExgFXDKgj/Ka6VQy tuZal11vRiWnP6mU0vu9Ih1K1GdOoDAAEAdwlWfYaybPxhriIQnfLoHF5xpZXNFlOf U/cWZtqdU5sAQ== Date: Tue, 27 Oct 2026 08:36:36 +0000 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , 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, Josef Bacik , stable@vger.kernel.org Subject: Re: [PATCH 24/46] mm/userfaultfd: wake all waiters on unregister Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-24-6f74bec9a5bb@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-v1-24-6f74bec9a5bb@kernel.org> X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: C71641C0005 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-Stat-Signature: 5z54ywzhrz9r8q183qapx7wsmr19zxpu X-HE-Tag: 1793090213-530189 X-HE-Meta: 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 T3r7OKGy MGogZ1nuBZyRv7htzjW/hz9uSZNJfuNxyZxa1WPvwM1zNePbVjJtP/Jdr75L7YxAY+8DoxoynhtrxTotvHnWvdZgPSFvk4GAi8UiMPvaWkZGfVriZg/vVMRUMM6Of9gozkA12MbLRIilzBGYvjVEYHHqC9c7aqc5YFR4mHugXVS7yqvTc56SA+dx7too7F1uZUudVMB3ySc9jDh3a9RRToHCvZudfDyc3N1MDS53sJ/Ye+sWHzatKqQ+Q8YJaUU2Gx5Hs0UbPWruLLVzwAGLLgEZ/Fc9Mx/lG5ZMWde2EtejWfMPvMKI6Oq55OEl2gM/hWiH8uwtENtsjO+jl6dn9PjdjcBcdiaxOG5jLpxOKmN7ylCdZbW5nCsIkWf94w74l/uxtJ7hY1F6mmMS/r9CiNqzuGbuf9hFUf2Fv 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 12:17:44AM +0100, David Hildenbrand (Arm) wrote: > From: Josef Bacik > > UFFDIO_UNREGISTER only wakes pending faults if VM_UFFD_MISSING is set. > Threads waiting on write-protect, minor or RWP faults can therefore remain > asleep after unregistering a range that does not track missing faults. > > Wake pending faults regardless of the registration mode so they can retry > without an explicit UFFDIO_WAKE or closing the userfaultfd. This matches > the existing behavior for missing faults, including removing unread fault > messages for the woken waiters. > > Fix generated by an LLM and sent by Josef Bacik in private. > > Fixes: 63b2d4174c4a ("userfaultfd: wp: add the writeprotect API to userfaultfd ioctl") > Cc: stable@vger.kernel.org > Signed-off-by: Josef Bacik > [ david: rebase; simplify description ] > Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Lorenzo Stoakes (ARM) > --- > mm/userfaultfd.c | 22 ++++++++++------------ > 1 file changed, 10 insertions(+), 12 deletions(-) > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index 7e30b5ff17be1..2122676c4220f 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -3977,6 +3977,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > > ret = 0; > for_each_vma_range(vmi, vma, end) { > + struct userfaultfd_wake_range range; > + > cond_resched(); > > /* VMA not registered with userfaultfd. */ > @@ -3994,18 +3996,14 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > /* Prevent new userfaults from being queued after the wakeup. */ > vma_start_write(vma); > > - if (userfaultfd_missing(vma)) { > - /* > - * Wake any concurrent pending userfault while > - * we unregister, so they will not hang > - * permanently and it avoids userland to call > - * UFFDIO_WAKE explicitly. > - */ > - struct userfaultfd_wake_range range; > - range.start = start; > - range.len = vma_end - start; > - wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range); > - } > + /* > + * Wake any concurrent pending userfault while we unregister, > + * so they will not hang permanently and it avoids userland to > + * call UFFDIO_WAKE explicitly. > + */ > + range.start = start; > + range.len = vma_end - start; > + wake_userfault(ctx, &range); > > vma = userfaultfd_clear_vma(&vmi, prev, vma, > start, vma_end); > > -- > 2.43.0 > -- Cheers, Lorenzo