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 53E2F26AE6 for ; Sat, 10 Aug 2024 14:00:30 +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=1723298431; cv=none; b=moqq3B0q/AKMXvmf6JYRd6CAsxDHuxL52zJTnMj4hnGYR1tjI+iR4i/NEi8r+Od1X5fZzSLg7LWT0Chsrr32eO5okpQHOVIvp3RB6TarqiKgqC1Tek0ZO7d68Eg10wQ2Y9VVlsW63IEOJ8gQc0MxFmOqn7eyPyBHPYaZ0buRg+Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723298431; c=relaxed/simple; bh=Cj1Yx0PJFEYVxLn4UyvZAIGlvRL72QXzxSOUQM3nhDE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fPxlN8OU0NHyR7h10EJcMI8fXmRhRMmr/Zekjy01LivcIVEHw6JkC+YDarz/dFbZkJktBqTAJHw0fH/S+UML/7OsSv7nvHTnuBSITv4Rzsc19hNt6OFwGKrYyhJ0aYVr0X9XsTFTtqyiVNA4nWZ4+kbQZcUUV2QAv6wDkbE8W4s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none 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=Ca8U+fKT; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none 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="Ca8U+fKT" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1723298429; 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=624V9XyG5KuMz5zJt7ndl3ScBb1+yoRWVwukoiM9UV8=; b=Ca8U+fKTH1+eWDX560GHE4WsMtwhHR8KtV1zO7l5Czis2+0QY6lq4m0Mm1VcGWfyVrOvr5 5sy2mit7+Kj8V6PZ/k/26STJDjR2FRIXRiVNaHOOiTQrqEz9JoZZyazjpynhQ0Rl+rd6rf zLshXuH2B0D0y3vm9jC12YY30hS0TY0= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-66-q4Qa9PKFOGqoKeri_5PBrQ-1; Sat, 10 Aug 2024 10:00:25 -0400 X-MC-Unique: q4Qa9PKFOGqoKeri_5PBrQ-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 734B01956080; Sat, 10 Aug 2024 14:00:23 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.43]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 133F419373D7; Sat, 10 Aug 2024 14:00:18 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sat, 10 Aug 2024 16:00:21 +0200 (CEST) Date: Sat, 10 Aug 2024 16:00:15 +0200 From: Oleg Nesterov To: Andrii Nakryiko Cc: linux-trace-kernel@vger.kernel.org, peterz@infradead.org, rostedt@goodmis.org, mhiramat@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org, paulmck@kernel.org Subject: Re: [PATCH 7/8] uprobes: perform lockless SRCU-protected uprobes_tree lookup Message-ID: <20240810140015.GA21800@redhat.com> References: <20240731214256.3588718-1-andrii@kernel.org> <20240731214256.3588718-8-andrii@kernel.org> <20240808134007.GE8020@redhat.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: <20240808134007.GE8020@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 On 08/08, Oleg Nesterov wrote: > > On 07/31, Andrii Nakryiko wrote: > > > > static DEFINE_RWLOCK(uprobes_treelock); /* serialize rbtree access */ > > +static seqcount_rwlock_t uprobes_seqcount = SEQCNT_RWLOCK_ZERO(uprobes_seqcount, &uprobes_treelock); > > Just noticed... Why seqcount_rwlock_t? > > find_uprobe_rcu() doesn't use read_seqbegin_or_lock(), > seqcount_t should work just fine. Please ignore... I forgot that seqcount_t is not CONFIG_PREEMPT_RT-friendly. Hmm. __seqprop_preemptible() returns 0, this doesn't look right... Nevermend. Oleg.