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 8C8B4606A321 for ; Mon, 26 Oct 2026 23:25:45 +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=csHXg4wZ Received: by kanga.kvack.org (Postfix) id ABF3B6B05DE; Mon, 26 Oct 2026 19:25:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A70076B05DF; Mon, 26 Oct 2026 19:25:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 986A46B05E0; Mon, 26 Oct 2026 19:25:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 671896B05DE for ; Mon, 26 Oct 2026 19:25:44 -0400 (EDT) Received: from smtpin12.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id EB0A6C08A9 for ; Mon, 26 Oct 2026 23:25:43 +0000 (UTC) X-FDA: 85366361766.12.1B30719 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf13.hostedemail.com (Postfix) with ESMTP id 1C1AE20003 for ; Mon, 26 Oct 2026 23:25:41 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=csHXg4wZ; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793057142; 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=d4MV77Ak5yM3C1+7NxJwT8IeWvwmREROuL+a3NtDfRQ=; b=wC+pASoTQ9PtW43H6iv7Z25sqDaNrTkhsES5DNuuBrPwl8b01OrsXireP0QF8gGaLnM9mB Cc0X105TAy/2ypzQcAynLiheBdn7gn50ipYKcoWFy5NIJ/mDvrEGV7V8NUm/hfCY0ZHpYQ K/4yNihYqfhQFP1b9v69SUyWULR8W+M= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=csHXg4wZ; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793057142; b=xq1l1G6rPRPvjA65294OLFcueiPo6lCKeLWpQ0mIm2U/IQgIYa5/taZcLIMC0Cmf2wkbeW SuJKbGjvQlb+aMBzS6qoGEdiRuVwsTYesdenqpojfxbSyKLORGlk3Ails8MahCLFbzhucT GC+8KwrrZpJnffasSnrs5laI/6nV5q8= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 3FB5940349; Mon, 26 Oct 2026 23:25:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD50C1F01825; Mon, 26 Oct 2026 23:25:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793057141; bh=d4MV77Ak5yM3C1+7NxJwT8IeWvwmREROuL+a3NtDfRQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=csHXg4wZ8V2CmRF41ciyNKcq+nBGY98nOFGquFQV1I4FOR2ZqNkkrBhldXkbQA73s kqedJrXPlEw/GuLeiEQWDKrNumdYNi7vhd3rTRVxjzw/ieirH3dPmp6u/as6YmvrVJ iZVtw5PMFX/jnw2wY7gllsWdINeETnRlf6f6Vsm9gTVUB/vzHDYRNW77UUNKHK5vf0 Bqeq21Tg4d6xJhLwKyTxEuaoXxDsLIbY0SrDQTLoSeu3UpGhMLhfsPmkHFvrYS/6oI c2/1w6D8Hg0KPF7JckRXaIQGKRF2A3XeW1iG0jHdwzqpLBslT2ot9ceobK3MBvzzoe qXYq7+4TRovEQ== From: "David Hildenbrand (Arm)" Date: Tue, 27 Oct 2026 00:17:45 +0100 Subject: [PATCH 25/46] 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: <20261027-fixes_core-v1-25-6f74bec9a5bb@kernel.org> References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> In-Reply-To: <20261027-fixes_core-v1-0-6f74bec9a5bb@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=2728; i=david@kernel.org; h=from:subject:message-id; bh=E+83r7S624k5EPCZEmcEXyyfHzl5/kgAEPI++IJBHPI=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLLu35+WIeW5rKpx0pvbIdt016lonXeLtHmhY9T1TzZjs 2/d3hvsHaUsDGIcDLJiiixBwfcNXr5cV1vtxscMM4eVCWQIAxenAEzkkyUjQ1votYCOD5eP6p1d wta/KW2Lx6N81v1HnfwbZF37HwhPCGD4p3Rb9PXpo3MvSN91cbu8pm+zTknZg8xeGZ60n/eON9n vZAIA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Queue-Id: 1C1AE20003 X-Stat-Signature: jhmjozkhw5pf11w4ocxhyxoxgotnmjh4 X-Rspamd-Server: rspam06 X-Spam-Status: No, score=-19.1 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,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793057141-911876 X-HE-Meta: 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 stl1cKEJ /7VWk4zwBjzf4VzD+aLdsK/EjFp6RTY1zpmva3WlNOD43DYYvcBADCGow97+yLSd6T4qfCqTXd8cud9IcebaGrz8WFYaxaR8L3vByxh/UQ8O7GLIAoWBrE9x5GkEIhKdnRXL+0H4pzlRrLej/onZMpVgETc8h/tdwL2DMJ0w3fcCNt5tmyfcvAazCVCp+OW5ayufdb5R0eg1DNXtJsgKF+FRBUs07NqoE/GPaeO2M+4CQrRnQYpTOfqasYi+fT0Y5b0lDLGKlmcLjZWvEcK74pZ4TVZ4kqugR4pz6WwxGQ0GwTNaV7sEBv8v9VwZOpdFzvlxlJA9HzcKkKq3CeSmMR61Wtsmy3mJQ7h7IQMNqebZflR+Cd4j4+/cCuw== 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 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 2122676c4220f..710e913c73bfa 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