Re: [PATCH vhost 4/6] virtio_net: big mode support premapped

[kernel test robot <lkp@intel.com>]

Hi Xuan,

kernel test robot noticed the following build warnings:

[auto build test WARNING on mst-vhost/linux-next]
[also build test WARNING on linus/master v6.9-rc3 next-20240411]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Xuan-Zhuo/virtio_ring-introduce-dma-map-api-for-page/20240411-105318
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
patch link:    https://lore.kernel.org/r/20240411025127.51945-5-xuanzhuo%40linux.alibaba.com
patch subject: [PATCH vhost 4/6] virtio_net: big mode support premapped
config: i386-randconfig-062-20240411 (https://download.01.org/0day-ci/archive/20240412/202404120417.VUAT9H5b-lkp@intel.com/config)
compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240412/202404120417.VUAT9H5b-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404120417.VUAT9H5b-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/skbuff.h:28,
                    from include/net/net_namespace.h:43,
                    from include/linux/netdevice.h:38,
                    from drivers/net/virtio_net.c:7:
   drivers/net/virtio_net.c: In function 'page_chain_unmap':
>> include/linux/dma-mapping.h:75:41: warning: conversion from 'long long unsigned int' to 'long unsigned int' changes value from '18446744073709551615' to '4294967295' [-Woverflow]
      75 | #define DMA_MAPPING_ERROR               (~(dma_addr_t)0)
         |                                         ^
   drivers/net/virtio_net.c:449:28: note: in expansion of macro 'DMA_MAPPING_ERROR'
     449 |         page_dma_addr(p) = DMA_MAPPING_ERROR;
         |                            ^~~~~~~~~~~~~~~~~


vim +75 include/linux/dma-mapping.h

b2fb366425ceb8 Mitchel Humpherys 2017-01-06  64  
eba304c6861613 Christoph Hellwig 2020-09-11  65  /*
eba304c6861613 Christoph Hellwig 2020-09-11  66   * A dma_addr_t can hold any valid DMA or bus address for the platform.  It can
eba304c6861613 Christoph Hellwig 2020-09-11  67   * be given to a device to use as a DMA source or target.  It is specific to a
eba304c6861613 Christoph Hellwig 2020-09-11  68   * given device and there may be a translation between the CPU physical address
eba304c6861613 Christoph Hellwig 2020-09-11  69   * space and the bus address space.
eba304c6861613 Christoph Hellwig 2020-09-11  70   *
eba304c6861613 Christoph Hellwig 2020-09-11  71   * DMA_MAPPING_ERROR is the magic error code if a mapping failed.  It should not
eba304c6861613 Christoph Hellwig 2020-09-11  72   * be used directly in drivers, but checked for using dma_mapping_error()
eba304c6861613 Christoph Hellwig 2020-09-11  73   * instead.
eba304c6861613 Christoph Hellwig 2020-09-11  74   */
42ee3cae0ed38b Christoph Hellwig 2018-11-21 @75  #define DMA_MAPPING_ERROR		(~(dma_addr_t)0)
42ee3cae0ed38b Christoph Hellwig 2018-11-21  76  

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