From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6848121C9FD; Sat, 15 Nov 2025 18:05:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763229952; cv=none; b=r0O4UaXqiq6Biv0uKlPKFlTzIFDkKo+Rb+7SYpuJGE/ETW0/6OPYEUGtX2/YwBfM08pp9af1TC+bzlWMPYvOJNvcnRWNUoHs2Qa3wNUgRUFWRXLiutMX971fnNvstr2k95NejK0E+/BuA5fceakhqNPyWe22WNX7o3F1EhNe6kk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763229952; c=relaxed/simple; bh=wvUeJI+DQ6+5SXIRBrGQ2XvF6W1kb5RLVw8OzwUxO2M=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=k8xEtLzW3ORGfnzmRL8SkoHSdUbru9nySjmVJKmFiTywbWr8lqGNJhydnayCmM8YZPomkdTs8Tw7+ss7jgzQgtvgEByod3+IYrZ3eBzeCdXYnca7bJ2AvB4iqJElWolWmUMj0p0TVOsuzHpQv5SGA7BUtDw0VtS7am8bvCysAIA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LnAsuQdZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LnAsuQdZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4263C4CEF5; Sat, 15 Nov 2025 18:05:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763229952; bh=wvUeJI+DQ6+5SXIRBrGQ2XvF6W1kb5RLVw8OzwUxO2M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LnAsuQdZQfdOUNV6MATOCoxHSrFYsX/MdUFL323mV8HqIbd81xoVr3bdvJ9HPebH5 oSq7BQJfVu+IrWONB0rgCtP1kBJxSoZA7AZDWY8MO1g7Y9Db0ynAFK5teKdlyJLiKk UMaVWoKFq03YtsKj7N4HPlpWfR2BBGWa/I9smxKJpF6BS9Qastb7uCIMf+feT2E4TT wvo+VJroVt9iiU3fENZveCa6i7CT/gJEeHAnMPRFQaiXUEeNmc5cTneDzwTpeyWnS8 UrdvVTl5MMOTiHdcZLlYKD24Z74zwq5oXSLgxS/2j4NQqzxTtQZ6lf3xgIgazSAAXj kHXzLEUW5S9oQ== Date: Sat, 15 Nov 2025 20:05:47 +0200 From: Leon Romanovsky To: David Laight Cc: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org Subject: Re: [PATCH 1/2] nvme-pci: Use size_t for length fields to handle larger sizes Message-ID: <20251115180547.GC147495@unreal> References: <20251115-nvme-phys-types-v1-0-c0f2e5e9163d@kernel.org> <20251115-nvme-phys-types-v1-1-c0f2e5e9163d@kernel.org> <20251115173341.4a59c97f@pumpkin> 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: <20251115173341.4a59c97f@pumpkin> On Sat, Nov 15, 2025 at 05:33:41PM +0000, David Laight wrote: > On Sat, 15 Nov 2025 18:22:45 +0200 > Leon Romanovsky wrote: > > > From: Leon Romanovsky > > > > This patch changes the length variables from unsigned int to size_t. > > Using size_t ensures that we can handle larger sizes, as size_t is > > always equal to or larger than the previously used u32 type. > > Where are requests larger than 4GB going to come from? The main goal is to reuse phys_vec structure. It is going to represent PCI regions exposed through VFIO DMABUF interface. Their length is more than u32. > > > Originally, u32 was used because blk-mq-dma code evolved from > > scatter-gather implementation, which uses unsigned int to describe length. > > This change will also allow us to reuse the existing struct phys_vec in places > > that don't need scatter-gather. > > > > Signed-off-by: Leon Romanovsky > > --- > > block/blk-mq-dma.c | 14 +++++++++----- > > drivers/nvme/host/pci.c | 4 ++-- > > 2 files changed, 11 insertions(+), 7 deletions(-) > > > > diff --git a/block/blk-mq-dma.c b/block/blk-mq-dma.c > > index e9108ccaf4b0..cc3e2548cc30 100644 > > --- a/block/blk-mq-dma.c > > +++ b/block/blk-mq-dma.c > > @@ -8,7 +8,7 @@ > > > > struct phys_vec { > > phys_addr_t paddr; > > - u32 len; > > + size_t len; > > }; > > > > static bool __blk_map_iter_next(struct blk_map_iter *iter) > > @@ -112,8 +112,8 @@ static bool blk_rq_dma_map_iova(struct request *req, struct device *dma_dev, > > struct phys_vec *vec) > > { > > enum dma_data_direction dir = rq_dma_dir(req); > > - unsigned int mapped = 0; > > unsigned int attrs = 0; > > + size_t mapped = 0; > > int error; > > > > iter->addr = state->addr; > > @@ -296,8 +296,10 @@ int __blk_rq_map_sg(struct request *rq, struct scatterlist *sglist, > > blk_rq_map_iter_init(rq, &iter); > > while (blk_map_iter_next(rq, &iter, &vec)) { > > *last_sg = blk_next_sg(last_sg, sglist); > > - sg_set_page(*last_sg, phys_to_page(vec.paddr), vec.len, > > - offset_in_page(vec.paddr)); > > + > > + WARN_ON_ONCE(overflows_type(vec.len, unsigned int)); > > I'm not at all sure you need that test. > blk_map_iter_next() has to guarantee that vec.len is valid. > (probably even less than a page size?) > Perhaps this code should be using a different type for the addr:len pair? I added this test for future proof, this is why it doesn't "return" on overflow, but prints dump stack and continues. It can't happen. > > > + sg_set_page(*last_sg, phys_to_page(vec.paddr), > > + (unsigned int)vec.len, offset_in_page(vec.paddr)); > > You definitely don't need the explicit cast. We degrade type from u64 to u32. Why don't we need cast? Thanks