From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f169.google.com (mail-pl1-f169.google.com [209.85.214.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B3EF3AC0CB for ; Mon, 27 Apr 2026 16:40:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.169 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777308002; cv=none; b=SbdZzuAzxTA0ddvw7ZIDZQhR244N4KO2U7Hpan3mUoOlb102+K3b8S2UNL7YmHAnjM3GUTrIlmP0kwyCnai7uAoTRPFssCFU0Z6KApsm8LcPaVrCF8vq8KbDBXccaGFlHhiozvIk8FVfGxiBqV/juqd4PhBvCUEHH7AiGVKtcqs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777308002; c=relaxed/simple; bh=ELm9WL56BWn8XsVieKjsOyOl1nxE9yjcplz5KpQGR+E=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qqmKzC6YM7teGtQDo46PiiG/LDuko9Dby9kEn3rFe2xdyDGr4UGLsmpoQ/nQVO41J6DBx9u4Hia7LFnjRr/FFAi36ddajrPuh2yL2uxWytmn5l9yjA3kSxEq7rTxdtugTl9QsohZQFcNSFWsyVCSLQuM8cqemLVp/NmKUP24tV8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=hTpk0FJ9; arc=none smtp.client-ip=209.85.214.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="hTpk0FJ9" Received: by mail-pl1-f169.google.com with SMTP id d9443c01a7336-2b243198058so460715ad.1 for ; Mon, 27 Apr 2026 09:40:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1777308001; x=1777912801; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=T1r6n/7OP5VXencUpZp7irvZXo3Q7ZpTXl+NYS+r5PI=; b=hTpk0FJ9t2VFhHQo9poiVlDfvB/MP0HWGzTReU/fkQch7YMciUlebXw+yxT2yA71Sc EPVDGe47ILw5+nLeJQGh6egPq2+Q/TCWfOmAUf1e7buUreTX1F05KhiSklsVEGyA6y2t oOjxM+JjNZG+3Uy63obuiFksdLGoozNcHocqEKz/lg3Zt2mTSi1KGGiS0m4jPkLwGewv nSuzFNQp8ZFD7XN7FHIrAG8fsxNxKv/j6gLUD1SQfvUf3+nZwmC+zZaNEaFVUMXAlC/Q 0POe3MtdGr6Mb1/jHn7a8E+Y/wRLsIBKRrCne1yte9ENGdik+o/AQc2EQYySbfDJIBN6 zWwQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777308001; x=1777912801; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=T1r6n/7OP5VXencUpZp7irvZXo3Q7ZpTXl+NYS+r5PI=; b=mnDAG5NZ8i6yTffTEWC71hUsxWiaW09+9XGgVk5mV3hD0dtywAigDLM30OpwCiY1D5 TThZ/NQZE8Im8zZ1ND7PUI7mxcOukMMWWiShKZj0mBSmsxsdubH0jY8+GzYwdSznIVsS r+bqq/dYPboJAPuEvw+KErykriIiolYF6BimuzNnt+vAF/Tymzfdo4yszclgpfdi3ZeE i2VxzcHJrwccNYTFYzs2ihClDGnicIbBk+I+qRf4LROaH9SmQED/OTSZI/tBVlYP94aj 4smF5hpdmVv9Kh//gLzz5NKnJfaDwwhPjy7Xoi5vUsYERoXh3G/2/5RKoNA1ceyjxpc5 AA2g== X-Forwarded-Encrypted: i=1; AFNElJ/srqtULSKscaIUERNB9KB2HeWqhvo4oDg3Pzgvot/KVM4LYoCBRCDdmW8eMvFv4dIWXMdXA/PXjcOmSNQ=@vger.kernel.org X-Gm-Message-State: AOJu0YxzmqOHLDhP9Vdaw5RNuDMkzWtR/5SrZLULQ8i25djA+oS55iK+ wQ78pg90FlZdu+uKgBVXGSCyAtmGlPqp0a8IzqGPp+gfRwSkR+eLGOkkzy/gpCtNDQ== X-Gm-Gg: AeBDieuwY1sWbA9spnqw0bS0JS+P+RB0RmdAf7u63qoLi09fQXkRvIZGAJcUXSvREcn I2koMJb5hPXKVud+pXp11o6vBcry3G6WwywX0MydM1F68P2WhVkX7u075H1NeCU6ODZntuquCJa RGkX47td9nxR0kAUkfEFLY7Bqe7Dfxu0b+pmXWS/hMJAG+csBSUuij9hod9mzBEcoc3W4tTEwTM kwGtXjRZftonuvaI1teTil7wdAbU5cedVt4pviL1RwbLGPm/th/XG6va3e4L7JkpSi0ztpEo4mp Bx5PXFS18tM+wyyrvqaawjmTalZAgzZ63ul6ENKjHd6WlvmHwJlBVnAkUwgg+W6Km2AKpo4PQqO wcRnuTmwWqsZQHW0t8raGVBqNfH0/8PItUNaosvlyvUQyzdiXr9smVB6mTPYvrKNylKxR9E3usK qY5z5fNIXmi0B27i+S7KnT/x7Eh/kWKJVTgWGNwyUF3ifZi5Bk8W9jxxFU5oHnNaJlxv5rATZ7P dwIn8unxXBtp7s3hL5I0gKjEcOZD90R910vGjmySoC/83cNdvjYVHG8OwVECcW+1co= X-Received: by 2002:a17:902:cec2:b0:2b0:5e19:1862 with SMTP id d9443c01a7336-2b97a407e44mr259295ad.5.1777308000438; Mon, 27 Apr 2026 09:40:00 -0700 (PDT) Received: from google.com (210.53.125.34.bc.googleusercontent.com. [34.125.53.210]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c7976fa40b2sm23658373a12.13.2026.04.27.09.39.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2026 09:39:59 -0700 (PDT) Date: Mon, 27 Apr 2026 16:39:55 +0000 From: Carlos Llamas To: Matthew Maurer Cc: Greg Kroah-Hartman , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Todd Kjos , Christian Brauner , Alice Ryhl , Miguel Ojeda , Boqun Feng , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Trevor Gross , Danilo Krummrich , Wedson Almeida Filho , Matt Gilbride , Paul Moore , stable@vger.kernel.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, David Stevens Subject: Re: [PATCH] rust_binder: Avoid holding lock when dropping delivered_death Message-ID: References: <20260403-lockhold-v1-1-c332b56cd8ae@google.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=us-ascii Content-Disposition: inline In-Reply-To: <20260403-lockhold-v1-1-c332b56cd8ae@google.com> On Fri, Apr 03, 2026 at 06:18:58PM +0000, Matthew Maurer wrote: > In 6c37bebd8c926, we switched to looping over the list and dropping each > individual node, ostensibly without the lock held in the loop body. > > If the kernel were using Rust Edition 2024, the comment would be > accurate, and the lock would not be held across the drop. However, the > kernel is currently using 2021, so tail expression lifetime extension > results in the lock being held across the drop. Explicitly binding the > expression result to a variable makes the lockguard no longer part of a > tail expression, causing the lock to be dropped before entering the loop > body. > > This was detected via `CONFIG_PROVE_LOCKING` identifying an invalid wait > context at the drop site. > > Reported-by: David Stevens > Signed-off-by: Matthew Maurer > Cc: stable@vger.kernel.org > Fixes: eafedbc7c050 ("rust_binder: add Rust Binder driver") > --- Acked-by: Carlos Llamas