From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 517A224C09A for ; Thu, 3 Apr 2025 12:44:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743684288; cv=none; b=Xq+TRabFYKM0rW52iEhERhQH2cFkOzKEIi+vLQWB0fQonieMECUUtvCPfJZiuyzukErh+hmfjC6Ssb70XQFUqxP2Orsf+FtMi/eM4wTjCI2W5Yg5Kj9vcQ0d4UTtTLB+gTbAxWY1vMh48U+wcAl7XvQ0Wr48p4suJN8AsKbmCGM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743684288; c=relaxed/simple; bh=THsjslv0PclgQM1w5C5ZeQBaIcQM+ov2tnQiCR+JXQY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ltv/JLIdag0gP/js+xfl+QUBoHT4No+3sm6xhRsfz0hj4+ZDzFQoBGtnO4t+fqyeWzZ1FJf6h40ppjkbeF02Q1pFAANfgI8vvfk03l7EijrmPWD1mZRIliNA9dYbZscsd9hH0snBZ6ucYbgFTu6dfQQQQffaTk/VoKDcjVjmaUM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Ohkjuat/; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Ohkjuat/" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743684285; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=k99cCVI4tAyR1lEvT/RV0Try5Bha7HjmpcxC+bC28K0=; b=Ohkjuat/Tn6Yerq5f+5hhfp1UcQbqfY0vkOP/g05F4OzIzzKkHG9BAeEIOo1FXFg+mRQKj 2B47xkT+WmHNisNOhLoxJ5DvkZ8aIxDUk3m9RdLubUD5hurWHeBEoIG3xdZzWP/bbUwtCt +j3WSa65MaSwl0mVyYjDRE1NsJs6Rds= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-210-7sMHfITfOQ6QGpM9_9Xjjg-1; Thu, 03 Apr 2025 08:44:40 -0400 X-MC-Unique: 7sMHfITfOQ6QGpM9_9Xjjg-1 X-Mimecast-MFC-AGG-ID: 7sMHfITfOQ6QGpM9_9Xjjg_1743684279 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 53A1A1809CA6; Thu, 3 Apr 2025 12:44:39 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.44.32.20]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 08D643003770; Thu, 3 Apr 2025 12:44:34 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 3 Apr 2025 14:44:03 +0200 (CEST) Date: Thu, 3 Apr 2025 14:43:46 +0200 From: Oleg Nesterov To: Sebastian Sewior Cc: Alexei Starovoitov , Peter Ziljstra , Andrii Nakryiko , bpf , Steven Rostedt , Jiri Olsa , Masami Hiramatsu Subject: Re: uprobe splat in PREEMP_RT Message-ID: <20250403124345.GC16254@redhat.com> References: <20250402105444.tW8UU7vO@linutronix.de> <20250402112007.GE22091@redhat.com> <20250402113142.GG22091@redhat.com> <20250402120649._gQHEtYM@linutronix.de> <20250402121228.GH22091@redhat.com> <20250402121624.lRIPMa_h@linutronix.de> <20250402135641.GJ22091@redhat.com> <20250402142349.GL22091@redhat.com> <20250403090834.rp7Y4KRt@linutronix.de> <20250403121107.GA16254@redhat.com> Precedence: bulk X-Mailing-List: bpf@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: <20250403121107.GA16254@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On 04/03, Oleg Nesterov wrote: > > From include/linux/seqlock.h > > SEQCOUNT_LOCKNAME(raw_spinlock, raw_spinlock_t, false, raw_spin) > SEQCOUNT_LOCKNAME(spinlock, spinlock_t, __SEQ_RT, spin) > SEQCOUNT_LOCKNAME(rwlock, rwlock_t, __SEQ_RT, read) > SEQCOUNT_LOCKNAME(mutex, struct mutex, true, mutex) > > so for these seqcount's seqprop_preemptible() returns false only if > the associated lock disables preemption. raw_spinlock always does this > spinlock/rwlock depend on PREEMPT_RT. Sorry, I wasn't clear... seqprop_preemptible() always returns false on PREEMPT_RT, I meant the "preemptible" check in seqprop_sequence(). Oleg.