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 202204B1B4A for ; Thu, 3 Sep 2026 13:59:33 +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=1788443996; cv=none; b=eete6fZH6nqWLPkbXpmvLkEX/gfHIdwHUF7fZSZuaBDT3oxx0BmY8M+2oO+GPcxO/NBgp4+vvDE8dRKEM1yWuNo7XsKJY1zzJQYCBC+zRjqQrORQSeqqmcx646/c++dpAupZ25KcceBFLRNyMD90ESXzdH5zJhnx3crbTnBZGGY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788443996; c=relaxed/simple; bh=c70qdPWoorRAaIZApbf0u5bpS41rBNnY8bznQUVsI1I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=gyfHGNefReBx6kFtdIAHEOf01H523vnfRdpsCDzJOCjVCkryI+awPfYptSddHGUf/WzmMz/MHzSuBoCdX6hKQ/HWwKDpNgBs2toHqTyh0ZAo5jXRNygTxiYPSTomDFzu3I5yEXmSQggBIlopBODFnvi1fp1pVvw9r/a+rwAldWQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JzCWvkB5; 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="JzCWvkB5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6785E1F00ACA; Thu, 3 Sep 2026 13:59:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788443971; bh=liaY4NC2sqVwf3er0oXP2F/nJmw+4O/kf3+17VC8Er8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JzCWvkB5JJJyHKCTiznMqKMgFXs6I0urpw97dPnBNdPHKxYrQoJDOBq82Y9//aPUP HArh9YowHcG5YO3SmdyBgcgdAX1iWBIdi/eRdnvFM7Sn62w5MExECo1aOwsY61TBzF dz/Qaajwvi5bfQWDkL5ff7F6AzAgu5Rg0VHAvCXRBwzUPNymjmEEtbzPXOC/WRzgu+ CznYZZ6I5tmE5ELwUXLA2TVKMu5X4ytSaVVjCfG3ZPhQ51S5UX76r8dKe1UgqwCNMh A6DrQsN4bKjIfI4ypeqRbsnD7T1D5pr5HXdFQ+twjCefynmGmnaFedfCY87sEUCPc/ ve+2sdmUPbIqw== From: Will Deacon To: Catalin Marinas , Karl Mehltretter Cc: kernel-team@android.com, Will Deacon , Mark Rutland , David Hildenbrand , Ryan Roberts , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] arm64: mm: Fix the lockless page-table walk in show_pte() Date: Thu, 3 Sep 2026 14:59:17 +0100 Message-ID: <178844029253.4160801.11282535964402738710.b4-ty@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260828174131.46825-1-kmehltretter@gmail.com> References: <20260828174131.46825-1-kmehltretter@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit On Fri, 28 Aug 2026 19:41:31 +0200, Karl Mehltretter wrote: > show_pte() walks page tables locklessly and can run with interrupts > enabled. A concurrent teardown can free a table page while it is being > walked. It can also clear a parent entry after show_pte() checked it; the > regular pXd_offset() helpers then reread the cleared entry and can derive a > bogus lower-level pointer and fault again. > > Use the lockless offset helpers with the saved parent entries, as > gup_fast() does, and pass the saved PMD to pte_offset_map(). > > [...] Applied to arm64 (for-next/fixes), thanks! [1/1] arm64: mm: Fix the lockless page-table walk in show_pte() https://git.kernel.org/arm64/c/a77644d009de Cheers, -- Will https://fixes.arm64.dev https://next.arm64.dev https://will.arm64.dev