From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7CFB4606A323 for ; Mon, 26 Oct 2026 23:25:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=dspzCNDS; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=nBlG95Jj DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; bh=wk8fHmHyhf8+gOZCyOM9u2jGkcwPVKHrhCqeaA1oNlE=; b=dspzCNDSa40Tj/ 8TAgndwJj27TF9+nvSDx8qaCIYzSvBbtAGribe//3K1IFfkzUcYpzRbt4gj3VEExULVF1pK0Oy6tQ ubWVFcBr8tr5c7kOqDsB61vreAkXRXnr8IJisMSrFZs4uF+7z5pThBx93Uyng/UcoInB5/I1sreh+ DS4vwsvvtJT0IKfYx/q28sOLwT/56Of9prlHtNZbb7iJwzkpylhP8Bi9yKvs8eWLKQyD8O9PbPzHG wuSyaHutSJLMghMAUzNozq6y3en7IaudVYeVeEDIUOBIryOnyAvFVSkoI+5pU5g0l4HXHF0ipOkkw CBcpjTAfENHqdXYYRKWg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLU4B-00000003QWB-0u7T; Mon, 26 Oct 2026 23:25:23 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLU4A-00000003QW1-2puj for kexec@lists.infradead.org; Mon, 26 Oct 2026 23:25:22 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 62E5B43A59; Mon, 26 Oct 2026 23:25:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ECB9A1F01829; Mon, 26 Oct 2026 23:25:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793057122; bh=wk8fHmHyhf8+gOZCyOM9u2jGkcwPVKHrhCqeaA1oNlE=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=nBlG95JjLTKQS1vsnDjG3NAtGsrJsDj/kWHYnsNPwR/Kc0irpHvaXwIB38KpMmMaH aJUO172YL7skHXpfcdKZZL3xndwdNhmEt2wuFrTZJ/6vzkZFBNrVgwh5j6lHQPqNr8 FA2RwtRCOwbPj6WLRe7QN8lDe412PsOUyKPQhJRU8dHjTUhNKSKli/BFSl1+hMJhFc B6E8BVR8WCWG26bqcALXH43Cp89W2ZE2U7vJW/EApfYOtJIoOvx1au8dpIsJblyBbu CQ/IA1Jopa5qol5YYDuCEkY2gLlCoYtmIuFrL7HJ2t1GVIN5bStSPzqSJg/dcuOsUC HfPG3U6ect9TA== From: "David Hildenbrand (Arm)" Date: Tue, 27 Oct 2026 00:17:44 +0100 Subject: [PATCH 24/46] mm/userfaultfd: wake all waiters on unregister X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261027-fixes_core-v1-24-6f74bec9a5bb@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, Josef Bacik , stable@vger.kernel.org, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2267; i=david@kernel.org; h=from:subject:message-id; bh=VWyRnUh5UUmddqRoYe/RjEaFtJoCER021E7Zl4sKkh8=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLLu35/m5/Zf4afPirVSuw4bnlaL3XBgkWdEX+7eJ/nbD qi3+js3dJSyMIhxMMiKKbIEBd83ePlyXW21Gx8zzBxWJpAhDFycAjCRDEWG/zUzPd5+511kL8MS WSulJCHq8trETpxv7aHmc0vVdIP2ZDAy3BXRPcHVdu+soPf6/ivasxpqVdJX5kcavou8kHhieqA YKwA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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) --- 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