From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 7BB5B217736; Mon, 24 Nov 2025 06:12:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763964752; cv=none; b=uSYZpDvuSQ8FDCMVxjbc+Kg3IvPZcfBpGmz344yfrnLD5jMMYHVwdz9nAa1rHGknN6F2i+LK4mnSszq/wJATTqsnwcHuGH2M1Dbanikhuk93N8oKSgfLOoDnDIJedNq8UF4vjYLHdNF8V3/Itp4sPr7m+qvabnK/09Pe7gDUKzE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763964752; c=relaxed/simple; bh=INSVYBbb1E6CIB2V0nuUCar+mTYYmoNlpmuEOEMDuLA=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=Upl47gxXZJJk/0xcbaNAI/5yNKEPtbNwPwvPMoHJN2JIqIQF9ZdKu04pYI3//Mzxk9w80EaqYS/3TcHgD8LsOis9b7EfIihxJj4WVqTwwZpUbcSrcIgrBsNwIGvNTek/jKE+/8GJb2olzWgKaiU69Iu79lDXuIb3H4saXAI+RkQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=gB0r2+qY; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="gB0r2+qY" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding :Content-ID:Content-Description:References; bh=Z4mpNf1BIRqsb//AvdOD24l+kOdTjNMLa/8oJp+WiNI=; b=gB0r2+qYFrX2fpYnAbAqE6haFb RfJMzle8EyHBPLt39T/J1EKj29mR8d3AE1mR3n8CE3Si4nD1HAm45+idOFExtUaIlu16pBvBa86l/ w96yrlHj5gRKg/WnFqkqueXTXDXBtI1Sp6kB4JZqAjn9XUIv1NBIZ9xi5d1uIXWcsd8xEkVM/kOq4 3gOkrPC6kf11pS9aRUFka8n4YjJTtj7RiO80SCF7G+/vXP0psKiehJTFTfOt4rcVyHkb+z1uMBUlf dJl52wPwBvmQhmlsOs7N6YVAnnw2E91r3cpoDF7S0WRptRczxcPfBTrqwXacK26EkY/ipETMW3YPa crnVygFA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vNPoG-0000000B8JO-3nwL; Mon, 24 Nov 2025 06:12:24 +0000 Date: Sun, 23 Nov 2025 22:12:24 -0800 From: Christoph Hellwig To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, Mikulas Patocka , Zhaoyang Huang , Dave Chinner , linux-fsdevel@vger.kernel.org Subject: calling into file systems directly from ->queue_rq, was Re: [PATCH V5 0/6] loop: improve loop aio perf by IOCB_NOWAIT Message-ID: Precedence: bulk X-Mailing-List: linux-block@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: <20251015110735.1361261-1-ming.lei@redhat.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html FYI, with this series I'm seeing somewhat frequent stack overflows when using loop on top of XFS on top of stacked block devices. This seems to be because this can now issue I/O directly from ->queue_rq instead of breaking the stack chain, i.e. we can build much deeper call stacks now. Also this now means a file systems using current->journal_info can call into another file system trying to use, making things blow up even worse. In other words: I don't think issuing file system I/O from the submission thread in loop can work, and we should drop this again.