From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f54.google.com (mail-wr1-f54.google.com [209.85.221.54]) (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 7400922FF22 for ; Fri, 13 Feb 2026 17:47:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.54 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771004848; cv=none; b=QmNNH693hah4WzOx6i1AHyUGrLVvDd+Lkp3lP8q49X+bKKr09rpnAr3mLq1BPGaPIq6a7tNZIOOSSx2K1I6kHydd8MS4ooK67eyr9c/qqQMpVRTru4WB8y/1FSfP50A2e8rZfz23IPtrnIbzDnmgu9vi3DokwOmH+4QwgYkqAwQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771004848; c=relaxed/simple; bh=cVUP1khg9y77f5SqQCygYm8i6x45YeX2k4zXUc1LA5A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=te81Hu0L98xPA7xrElSSuk0Ozi+t9MMffYtNVkR2Frhsa6KdO1ACz3ArgKikLhQXEeZBdW2WoRRuPiSO/3nynjml3qb6AbQQ/5odtzS+xhUIqMuxOHes4iQoribrR+G/DHGaILjDeQsQ3msYFA+AIDYfPQXYvogF0RDbG6BzpeI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=P6AxjJvM; arc=none smtp.client-ip=209.85.221.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="P6AxjJvM" Received: by mail-wr1-f54.google.com with SMTP id ffacd0b85a97d-43767807da6so741417f8f.2 for ; Fri, 13 Feb 2026 09:47:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1771004846; x=1771609646; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=PosW/YBGoUIFQFPUNvEYuUV8ta1niybZBwavkBZhlcg=; b=P6AxjJvMA0wR9t9G2Jt/o+X79XY6HP2gB4U/n7IgJ13/IqSe2sw4ri4czwETbvzR2q YKfQdn3/hIz1k6WJ6Phy1Mz8ubpEF0KaRYLc7m7tZRq7/8esaCGgqQ38iuLwxjOcwK+X M3a7gNpBSMP2xlap+lZuc2EndjPD60+q5qKPC7VlozgZSBllhXW9JAAmfyOB5/WBtg+P nvnXKABA99hpdZZjptAEyvG8AjgH1ZHw0jojBaCdC5rb8k+n9I4dTdBcMHCrcDQ6bQIa eJIPhqMRjJR/KS8fZk4igx7di5mb5NCZ9Upg/esqFu+Byc5w+spKxuAW67uZBzyMFV3I AohA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771004846; x=1771609646; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=PosW/YBGoUIFQFPUNvEYuUV8ta1niybZBwavkBZhlcg=; b=joQJaZ1ZiLY9ezEBVaa4qMJHfdfmLvnn5zMi7yxKCwa5Pjnip0xg4uLUuQJuMLSSLy cmlGsgzFL4SUi0PKZxOySlBaQ3VRwzVcFmjdUsGg6JmMGEg9K/sz12kjT+QAxhYy7Pdw xEd7c0+TeydwXE7r/v91gi6pNYRSVMmKHl9PS5NNzMuslE6WYWRl8ELXMexxciDeizTB XmJITd8u8r7bwiiIf2NfZ8NdEQwHP1el2hfPDty8h8y17e4F8Jxgdu7rpshEeXwbqJxl AGVHJFYoL0QENlyJUEo5LZqYf9mhAaBiOwyKqfa8EqsJ6sPEc5fk+zG8nOoOyjC440VX 38cQ== X-Forwarded-Encrypted: i=1; AJvYcCXN3BqJx8aRbVhD2ROqefTMax0drY0TgDveAKne8ah5j/kHXXb8h0TQ4VmzdPJn+pwHHYgWgI/JFK1HDzbr@vger.kernel.org X-Gm-Message-State: AOJu0YypdT4fI/kFA/q665XNKfMkEkfF1HNJNsgVm8itKYiV6L83uk/W S3M9WUSlg6+AVZ8A5bMJeEI23tDNYf+FX+0HuXZp2aONVNgBUX/di/sB X-Gm-Gg: AZuq6aIig1+rR0oZgtXTkp9z8NC8GByRNWJPj8X+fEhbC5QIvFqcF5r8uaqxogbPVXz aDgB2vWsm76IVOdBmEeGuQwe4L/UoIzkm6WanwmSjYWihZsboQoPL/7VTF2p+37hhpOUqd3Fgyw 6b/JiayvKgRboU0MzQ3n5yv5EFvDuit1f+jjFmwwaPxiJBcA7BlcXmGac6Ssj+I1OHx09E8XpzL 262d1I62kjO+LW2G6mC7WX3kNXPSWpSUOVxCgIODuAOnn1s3cLPKeLuWTfXZlvII1McOgzAHp+3 xOvntnrvGSOdcgTzS/w2zS1HEG4BVAMyyha1P+4Iklso1B0uRtP98x7i9FtlECkR7MWo2LHv4V9 w8EpCFECFoKFxj7Ri01DeQn2cCDRJyUmpovdzY9OAEauftmARkKJgd/MJQZ4f8Ovd1aoU4UCWEi dhTMIeE8DQiRuLGZSnB2o= X-Received: by 2002:a05:6000:238a:b0:435:e520:d1d7 with SMTP id ffacd0b85a97d-4379793f0d7mr5204850f8f.63.1771004845710; Fri, 13 Feb 2026 09:47:25 -0800 (PST) Received: from localhost ([212.73.77.104]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-43796ac8d82sm7274389f8f.31.2026.02.13.09.47.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Feb 2026 09:47:25 -0800 (PST) From: Askar Safin To: hpa@zytor.com Cc: christian@brauner.io, cyphar@cyphar.com, jack@suse.cz, linux-fsdevel@vger.kernel.org, safinaskar@gmail.com, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, werner@almesberger.net Subject: Re: [RFC] pivot_root(2) races Date: Fri, 13 Feb 2026 20:47:21 +0300 Message-ID: <20260213174721.132662-1-safinaskar@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <1FC2FB1F-BDA5-472D-A7DB-D146F6F75B16@zytor.com> References: <1FC2FB1F-BDA5-472D-A7DB-D146F6F75B16@zytor.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit "H. Peter Anvin" : > It would be interesting to see how much would break if pivot_root() was restricted (with kernel threads parked in nullfs safely out of the way.) As well as I understand, kernel threads need to follow real root directory, because they sometimes load firmware from /lib/firmware and call user mode helpers, such as modprobe. -- Askar Safin