From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 65D6918BC3D for ; Tue, 2 Dec 2025 09:21:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764667312; cv=none; b=keDzUpATlFT06sHfa654rYfwu6KqLSXePr431CrkHQyeHIGhz5k3TmV9ikf7448fODcgbP8aAHhxghiOTRh5poIwap20Tf9yWH9BgUfgMUirnnE+qRGiQo1wGIYuCtmK+545XJZQJZ22g8G2j4+94a6RmKDsJF+ElUmEX82bUeA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764667312; c=relaxed/simple; bh=AO6hgtyYBO0Bwa3KdlsW+5V0OKv3binbyIskvcDOcrs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FNYwwKRx/uP59Cpirjdypv7mA9N3L63XeSRUGfttA9wa1/oCsFSaEaJDoR6+xOxDvF2JBBx24bWGZsBx0ovpcR+SJMajDNjrkwL5webi/FRyRBcKA1oCOx+w/dQr4MdSiqoRG6VwJG4wvALPOP7K7ePcj0F2GtcQ+ausonfXOPc= 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=V8uBuWyU; arc=none smtp.client-ip=170.10.129.124 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="V8uBuWyU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1764667308; 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=AO6hgtyYBO0Bwa3KdlsW+5V0OKv3binbyIskvcDOcrs=; b=V8uBuWyUyt/gZw9TfcTxg1znEu8mWmlmRmRai8PfnbZHgAs3Yag/BmyF/qP0gc5xyPlmEr ziYnhJRISCOEJDTBjFTnQLJvIO0RTcJlAvi5AJ8u70k+twcDxiIFDViTo27PClpgYDm59z nbKpif3GFiqCA9WBk8YBZ3gTDIxC2fg= Received: from mx-prod-mc-01.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-617-cyz1bVeIOzCS9cOrX_I2fg-1; Tue, 02 Dec 2025 04:21:45 -0500 X-MC-Unique: cyz1bVeIOzCS9cOrX_I2fg-1 X-Mimecast-MFC-AGG-ID: cyz1bVeIOzCS9cOrX_I2fg_1764667304 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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9DEBF1956056; Tue, 2 Dec 2025 09:21:43 +0000 (UTC) Received: from fedora (unknown [10.45.224.180]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id AB8EE30001B9; Tue, 2 Dec 2025 09:21:41 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 2 Dec 2025 10:21:43 +0100 (CET) Date: Tue, 2 Dec 2025 10:21:40 +0100 From: Oleg Nesterov To: Ingo Molnar Cc: Peter Zijlstra , linux-kernel@vger.kernel.org Subject: Re: [PATCH -v2] seqlock, procfs: Match scoped_seqlock_read() critical section vs. RCU ordering in do_task_stat() to do_io_accounting() Message-ID: References: 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: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On 12/02, Ingo Molnar wrote: > > * Oleg Nesterov wrote: > > > On 12/02, Ingo Molnar wrote: > > > > > > RCU read-lock should not nest inside a read-seqlock > > > irqsave ->stats_lock IRQs-off critical section, > > > > Hmm... I agree with this patch, but is it actually wrong? > > > > I thought that rcu_read_lock/unlock is safe under spin_lock_irq... > > Yeah, true - it's allowed and not a bug, OK, thanks ;) > merely > discouraged inside irqs-off sections if it can be > avoided, and it's an inconsistency versus > do_io_accounting(). Yes, yes, agreed > How about the -v2 phrasing below? I also removed the > Fixes tags. Acked-by: Oleg Nesterov