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 F134F606A31A for ; Thu, 29 Oct 2026 20:39:48 +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=KGJhzxYl Received: by kanga.kvack.org (Postfix) id 1ADA96B05D6; Thu, 29 Oct 2026 16:39:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 185B56B05D7; Thu, 29 Oct 2026 16:39:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 077D96B05D8; Thu, 29 Oct 2026 16:39:43 -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 C882C6B05D6 for ; Thu, 29 Oct 2026 16:39:42 -0400 (EDT) Received: from smtpin08.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 5AC91401EE for ; Thu, 29 Oct 2026 20:39:42 +0000 (UTC) X-FDA: 85376829804.08.430CD1F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf18.hostedemail.com (Postfix) with ESMTP id 8F20C1C0009 for ; Thu, 29 Oct 2026 20:39:40 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=KGJhzxYl; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@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=1793306380; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=CAhC4MbhnDJXKKCQ+5YFJHRaqlB0ve7BM+PvgIjSMcY=; b=LXc0IkJNub3glDNTBMwkiA6nGRFieskmio2c5o8eVE+ixcyDRpL3S8y10c0gw/5L4Rzjc5 LglU0OgzIqZ4TVRPFzKZ2D9bdAolXQxFEl/Mmn3KN1PZJOWxGR0poO0v4cz1KElGhkUzuE qmrcYLXiZhxFocVTW2CghYzgId2J/dY= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793306380; b=J5jx+Kb7floF+ZyNP0TSEoq8voLgcp3NRF21raV4AB7+xyfVDRY/b9zNAY8eRS5+bVV/6x QHjoWJq9hjPyyhsZM7Vyhf9WM2Sen1VxQAbZNgXDzNk9b/9K3gGP1ygWpmdXsSxksP6P1c R4thHrXf4DewP3vcpAk8bGAQdhYzNOE= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=KGJhzxYl; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id B67E041AB7; Thu, 29 Oct 2026 20:39:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91BA91F01824; Thu, 29 Oct 2026 20:39:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306379; bh=CAhC4MbhnDJXKKCQ+5YFJHRaqlB0ve7BM+PvgIjSMcY=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=KGJhzxYl+9r92Bj9W2YAR+wgi/sM5nkmr2lgTbQ30j8ZUhL38hxRUC4bC5dp1p0E3 JHssW2r5kV05NN1RN0oNO86QRqKkSxnFUPWqVRO/1w8jPj0xBXyUFR1kMY+59f7FTY 9hZ0Drs+/V7tulyIr4vt7QO2GHInOb6FbOYl8Gq3QTUkufyiJLpdmPX7lLx8CWCV91 h9tesZc4td3L9agPTyeb8/iri3/sTsBiTHeu31Zd9M30RSZId3o/7i2lTFUMgD+EW0 5AxwI0RNtgE2rzG27RTB7FGyMtVkUfNrCk23sMzr/ddhNnQk/JNJAy8M0Bz7sROrk9 q2m2I+ZepkH5g== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:33:20 +0100 Subject: [PATCH v2 25/47] mm/userfaultfd: wake waiters when registration modes are removed X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261029-fixes_core-v2-25-a64ce7f83abb@kernel.org> References: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> In-Reply-To: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> To: 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 , 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 Cc: 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, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3002; i=david@kernel.org; h=from:subject:message-id; bh=p4m2oymzzbSLDXhAc0Cf9hknbaIjiA7t2PJNdiOyskg=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer21/bClg2vOzuLmVceYDuUKBTqGtbMq1QSm+LduOv F3V3JDUUcrCIMbBICumyBIUfN/g5ct1tdVufMwwc1iZQIYwcHEKwES2vmH4H3T+ZnsN28rm2Pt+ 3GWvjafpfElmyHwp0Fm41MjI86z5eob/lfGbmP428sZp9c5n652hqvnusTvPzKqadww7fm1e/+U ECwA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8F20C1C0009 X-Stat-Signature: j4gjjafmiiwyeyb9qo7zf88a77sf6ejh X-Rspam-User: X-Spam-Status: No, score=-18.8 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,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-HE-Tag: 1793306380-623200 X-HE-Meta: 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 BmBDcnGk FfpNx74L5kZCB4fAnMsY/HDRquj8dN6OpdHMS9qsawAQ8Aa3p3aRKhG3ARP9R1JWHv2aRegxjRxH1w+OH2UOFnMxm9kVT6qSfpkK/Wk19UeQd9KT3xIeCjtGvJfNwIei9GBZXVqwYFawFya/3J2WqQ30gd9ZZidZ9lSSqt6pY7P2JxWKcHttDFRTvk7b8Jqrf5oMAptR3BmPMHt3ihwFDaRpJKu1XJRXHtrYVHoWQGriRzkNhrkTaNFhY+ajF3Txvsq07NZiZYM1mdC8tgyVv01nK1LxGCH0aFiY7sM3THEDLreCFQK5Dzp8sgtWKzFv5g4qb9qvnbl04NjRwW0bRBFpD7nFrgozDqlyn6ADkuvyV0kP47pM/zU7kv7Z0zXQ2sshUz7mluqEOUQtBJdriRoOs+2k2al0gokki1/JcZmZblT4= 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 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 Reviewed-by: Gregory Price (Meta) Tested-by: Gregory Price (Meta) Signed-off-by: Gregory Price (Meta) Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Lorenzo Stoakes (ARM) Signed-off-by: David Hildenbrand (Arm) --- mm/userfaultfd.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index be630674fda9..03f1b15bfe63 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -2270,6 +2270,9 @@ static struct vm_area_struct *userfaultfd_clear_vma(struct vma_iterator *vmi, return ret; } +static void wake_userfault_range(struct userfaultfd_ctx *ctx, + unsigned long start, unsigned long end); + /* Assumes mmap write lock taken, and mm_struct pinned. */ static int userfaultfd_register_range(struct userfaultfd_ctx *ctx, struct vm_area_struct *vma, @@ -2287,6 +2290,8 @@ static int userfaultfd_register_range(struct userfaultfd_ctx *ctx, prev = vma; for_each_vma_range(vmi, vma, end) { + const bool any_mode_removed = vma->vm_flags & __VM_UFFD_FLAGS & ~vm_flags; + cond_resched(); VM_WARN_ON_ONCE(!vma_can_userfault(vma, vm_flags, wp_async)); @@ -2332,6 +2337,10 @@ static int userfaultfd_register_range(struct userfaultfd_ctx *ctx, */ userfaultfd_set_ctx(vma, ctx, vm_flags); + /* Retry faults for removed modes while the VMA is write-locked. */ + if (any_mode_removed) + wake_userfault_range(ctx, start, vma_end); + if (vma_is_hugetlb(vma) && uffd_disable_huge_pmd_share(vma)) hugetlb_unshare_all_pmds(vma); @@ -3648,6 +3657,17 @@ static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx, __wake_userfault(ctx, range); } +static void wake_userfault_range(struct userfaultfd_ctx *ctx, + unsigned long start, unsigned long end) +{ + struct userfaultfd_wake_range range = { + .start = start, + .len = end - start, + }; + + wake_userfault(ctx, &range); +} + static __always_inline int validate_unaligned_range( struct mm_struct *mm, __u64 start, __u64 len) { -- 2.43.0