From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793439990; b=25AyPhRT0LsWuzeqqV1vlIP/2TAQd2KaMMn1DmAfIpUbrMqQyPOtdW68UbEmWcKPHDRE 6z0qmYpGsNHRB47bH5M5/RMZhMgzGZ5j7Wy31KuXSzi4jzuy0ri+U+JoXi5UsGdWgD8u4 oeAaC9QLKo4of7clMGpY3i/D9cQlXSny6duXJOlM24h2hGVZjan9XuZmzv78PdYflSgS/ BdsTX5af+RXLGz0qCEtYZFoZWF6O5Igvd9xxPY+OQTXEIM5/OBcFgJ4LdWaxnq8jKS7il xZC/iL0ltFehsPdtVySHfFLWDkpbXg9sQxjxprgc9nPZL/sGIkeXh5VZeEslNGvC55w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793439990; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer:X-Developer-Signature:X-Developer-Key; bh=6rdFsSanvdSasr5hp2c+zM3yMNq0teCos7F9FeyTNnc=; b=Lu+vpu25J2CpKFKR8Dd4L9yjPq2Nq5u5VqhN2lnFddH44ayu5zEtUa4a70BMQvhTFGKO mDLoOx1hFoS3OiYYAc8WvNZ2J88F7rDaWObuwjbvUx+mNEN7GFDoU8KF4X4mfeTdyiCIa 85BFYcQsN9JDTxzNZe/zo2sJJ1PuTBrT0LOR5l1cEigoc5B9bd0Lr06PlgjhfkdM5A9L+ GwGqle0wFLGdilLY9gBffAX74Zg4fe5SdApJkFHBsaBJI9LzsBeMUyTA53XwfD2t/nwMP N1zohwDM13xYmHeAXMc0lq+LfeKBpT//mc226h+4uVjJP6SJRvtH7T1QDxS0m6KNZOQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Yugjn+pB; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D0D1B606A31A; Sat, 31 Oct 2026 09:46:29 +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=Yugjn+pB Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FC641F00919; Sat, 31 Oct 2026 09:46:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793439989; bh=6rdFsSanvdSasr5hp2c+zM3yMNq0teCos7F9FeyTNnc=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=Yugjn+pBYLqLBNC3xTiCz5oiW74vhvC7wFkycvRquO3PnYkqqxvJdBjpVVLOOf9a3 GMY5NPMvyim4j6zvtGkobuJQM6LHuop5J9jeU838zTWLADf6gS9mENKHqyeQ3U/cE2 tJ3QNIKkVHGA8XgYw0iQQ87Mz2ixJeN+SwIvqwqJfyG5NckD6CXkcAUg8jOqrL4xfa 4j3O2xRowLdRQSBYvwRe96Lht4Bnym9ZIAj/D5fzhJgLn932plRC2akFWJdgu9efrr PFVFdC6cmtsSCVrw0oaNlN0Ha4j0Xykq9Zmdvyk6cfI3okiXdYyvJvgkiQPI3PQ4x/ B7Mx6SnjXL73w== From: "David Hildenbrand (Arm)" Date: Sat, 31 Oct 2026 10:39:53 +0100 Subject: [PATCH v3 24/47] mm/userfaultfd: wake all waiters on unregister X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261031-fixes_core-v3-24-d6437171ecc3@kernel.org> References: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> In-Reply-To: <20261031-fixes_core-v3-0-d6437171ecc3@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, Josef Bacik , stable@vger.kernel.org, Muhammad Usama Anjum , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2433; i=david@kernel.org; h=from:subject:message-id; bh=jQmdKlit53in6eLyB5lf4macOO/l2TcVDsIv/EBmrGQ=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLKebs+QuqZh0vyitqWjpyf93yWBKxsFeRNZrt5UZ0/01 uPyqfjQUcrCIMbBICumyBIUfN/g5ct1tdVufMwwc1iZQIYwcHEKwESW2TH8lXjDYm1v2hI/s91y 7fU857DG/g2ne3flZlXO0qn8+vyaKCPD/kUxxXONRZa5rZX00Vw4Oe9ZxN3rE9xft8fcOiRdJvG cEwA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A 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 ] Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Lorenzo Stoakes (ARM) Tested-by: Muhammad Usama Anjum Signed-off-by: David Hildenbrand (Arm) --- mm/userfaultfd.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 3ca04b582329f..be630674fda9b 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