From nobody Fri Dec 19 12:48:25 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 85CEE258CD1; Mon, 14 Apr 2025 07:34:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744616091; cv=none; b=WXkd17fWRRvcbX1+YUVjvBuCZHSfQ7NA02+8tzDAzzqlR2JaKUTL8EYYRTSf8G9FVk+mbrzoZhIditxImBi6NQp8195MRNwRfjyf5jQ8T2ruUGSvx8GiYLcx1/oiNgzrNkYi5hX/D2lQeZ0AurOz4E9ktpBNHcCbjjCYz16baoc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744616091; c=relaxed/simple; bh=E/6AntGyGl9Dbs7IgIrXcGc8EjnJ/giiVsyu5K7Ojpg=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=UzNsMzu0NxDlQbYzINNau/8+69lg7mutLc+S496zmBIVvL4w0BHnJGLPy0CxQDt1iHkqawbuVxgN0J3d1zNTgQqTUdYKona69vDN15rQz/0Iju3D/vGqzwtG4dhdHDljFqcA1E+CawG3C51FTl5C2AkI6dyUb7e1Ow2PEP7Qx6A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=BAHz31KO; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=lfAYr1Aj; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="BAHz31KO"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="lfAYr1Aj" Date: Mon, 14 Apr 2025 07:34:46 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1744616087; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dagTIWiokxReXchhDuqcVKGxidfbB9hrqV3IiuAc6CU=; b=BAHz31KO06f9vnSpfPsLFQtZwVhwWguehRjqlj297Ps5R3WUtIKXsmCdoNOcJtgN7WyjFL TpT4Dp7aaeRhheIBKvI0LT0rZ0cNDtKAcUNNhQ5MAilIXUZTb6HSpuORwe7JO+nxqwl2ML 1s4/EKWmPDceZZNLNkfB7BSuUIJSOj4t/CD5ZbJJLwh7tgXyXNlrc6s+eD6xMWPXpn9UXP 687BO9Cdo7wGepr+QHebtLMPD2GwcIPw9fC2jcJvo4bBIXqDSoXKGy6KtH7p2noBqs/EBM 9ujtfTQAvPPyKNuoeDz6ME5PVG4Gm5vh32GRzCqSkre7Ltx2MjgiCkY40ISOsw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1744616087; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dagTIWiokxReXchhDuqcVKGxidfbB9hrqV3IiuAc6CU=; b=lfAYr1AjSI5ol/cmau6snRchurkaDwYPklWaqp6jXrCiM/6hIEydbTYv1SlvpQLtiZgXf+ 52B69uJxJQag3uCQ== From: "tip-bot2 for Ingo Molnar" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/merge] x86/fpu: Make sure x86_task_fpu() doesn't get called for PF_KTHREAD|PF_USER_WORKER tasks during exit Cc: Ingo Molnar , Andy Lutomirski , Brian Gerst , "H. Peter Anvin" , Linus Torvalds , Oleg Nesterov , Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250409211127.3544993-7-mingo@kernel.org> References: <20250409211127.3544993-7-mingo@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <174461608676.31282.200232256748421444.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/merge branch of tip: Commit-ID: c360bdc593b8a8b6e94166026728764085919cff Gitweb: https://git.kernel.org/tip/c360bdc593b8a8b6e9416602672876408= 5919cff Author: Ingo Molnar AuthorDate: Wed, 09 Apr 2025 23:11:25 +02:00 Committer: Ingo Molnar CommitterDate: Mon, 14 Apr 2025 08:18:29 +02:00 x86/fpu: Make sure x86_task_fpu() doesn't get called for PF_KTHREAD|PF_USER= _WORKER tasks during exit fpu__drop() and arch_release_task_struct() calls x86_task_fpu() unconditionally, while the FPU context area will not be present if it's the init task, and should not be in use when it's some other type of kthread. Return early for PF_KTHREAD or PF_USER_WORKER tasks. The debug warning in x86_task_fpu() will catch any kthreads attempting to use the FPU save area. Fixed-by: Chang S. Bae Signed-off-by: Ingo Molnar Cc: Andy Lutomirski Cc: Brian Gerst Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20250409211127.3544993-7-mingo@kernel.org --- arch/x86/kernel/fpu/core.c | 8 +++++++- arch/x86/kernel/process.c | 2 +- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index e4c2090..4a21938 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -683,7 +683,13 @@ int fpu_clone(struct task_struct *dst, unsigned long c= lone_flags, bool minimal, */ void fpu__drop(struct task_struct *tsk) { - struct fpu *fpu =3D x86_task_fpu(tsk); + struct fpu *fpu; + + /* PF_KTHREAD tasks do not use the FPU context area: */ + if (tsk->flags & (PF_KTHREAD | PF_USER_WORKER)) + return; + + fpu =3D x86_task_fpu(tsk); =20 preempt_disable(); =20 diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 5fb502c..7a1bfb6 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -109,7 +109,7 @@ int arch_dup_task_struct(struct task_struct *dst, struc= t task_struct *src) #ifdef CONFIG_X86_64 void arch_release_task_struct(struct task_struct *tsk) { - if (fpu_state_size_dynamic()) + if (fpu_state_size_dynamic() && !(tsk->flags & (PF_KTHREAD | PF_USER_WORK= ER))) fpstate_free(x86_task_fpu(tsk)); } #endif