From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 46CC7371CE3 for ; Sat, 4 Jul 2026 02:05:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783130751; cv=none; b=dfD3PJZBLIVxdyfC+p5JhW/14hgPzCtXIRoFF0DQ9aUi/ai/yRUC+GE7nQSBJIcONB5Z2fLVm9BfpybqtsAZDOZHkakrs4H7FB409koeo931LA21k3Sa8+nJ4PcUx6P7zYHyfpo+TpwbvU1oifeFLjDrmr2BdRBmob5BhxE1H2I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783130751; c=relaxed/simple; bh=Bymeqo7TJygbQDFx1b+mc+ZfhO7vUxNbkBkpgc1FSIU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CGexzgl4g+crcPjik9H1LPxru7cp3D72u5ERBuDMezEA+ycF2SNrnjVyzeh+7hE6QVedHmhWjYzagZCBpH9NYxCOj49SQwim7OcVJV5y20UjNKouBHdoo32rWGDJfUN5aX9B2PW6bV/JlJRM33uekHvys0ee4WSdUff57r5M/98= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hfCQ7v8T; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hfCQ7v8T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD3691F00A3F; Sat, 4 Jul 2026 02:05:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783130750; bh=LXOcPNzgegE6L6G/fMOjfbLXmHe7Z7CrfUSz7274nys=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hfCQ7v8TpmaDaRz4ItLLC52emgeSTOSpbC7yXZCrbMzoRQcu5Tlsz8w85divZUacW yE4+PtE1UKB9Poha36Yhkdbmod9lSp+FiL5LAtQmZUDN5R7kIQj88JW0ryZzT9XHDn TnD1n6AqKarTNeRl+1OnmpWGr/aWzc1mQqrLF0p8oLIK+VlIGxt0NxP8I6Pqncbj3t cuq977QDzN8MnJvaQwIf2GhLWFR3xjLrCc6v4JBaz3ewL0EshejbTjCBoud6prlEE7 nyCEJid5vHfOoOpMl5IzwdbJMXNie7kQ0T3tvZjXfHmTW08QEqhjGkx6/4L1TzIypL HFFqAedPMSv/g== From: Sasha Levin To: stable@vger.kernel.org Cc: Sasha Levin , Sashiko AI review , Lorenzo Stoakes , David Hildenbrand , Michal Hocko , Mike Rapoport , Peter Xu , Suren Baghdasaryan , Vlastimil Babka , Balbir Singh , Andrew Morton , Kiryl Shutsemau Subject: Re: [PATCH 6.18.y] userfaultfd: gate must_wait writability check on pte_present() Date: Fri, 3 Jul 2026 22:05:13 -0400 Message-ID: <2026070315-stable-reply-0019@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260702154907.975486-1-kas@kernel.org> References: <20260702154907.975486-1-kas@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Thu, Jul 02, 2026 at 16:49:07 +0100, Kiryl Shutsemau wrote: > userfaultfd_must_wait() and userfaultfd_huge_must_wait() read the PTE > without taking the page table lock and then apply pte_write() / > huge_pte_write() to it. Those accessors decode bits from the present > encoding only; on a swap or migration entry they read the offset bits that > happen to share the same position and return an undefined result. Queued for 6.18.y, thanks! -- Thanks, Sasha