Re: [PATCH v1 8/8] mm: Remove device private pages from the physical address space

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

Hi Jordan,

kernel test robot noticed the following build warnings:

[auto build test WARNING on f8f9c1f4d0c7a64600e2ca312dec824a0bc2f1da]

url:    https://github.com/intel-lab-lkp/linux/commits/Jordan-Niethe/mm-migrate_device-Add-migrate-PFN-flag-to-track-device-private-pages/20251231-123453
base:   f8f9c1f4d0c7a64600e2ca312dec824a0bc2f1da
patch link:    https://lore.kernel.org/r/20251231043154.42931-9-jniethe%40nvidia.com
patch subject: [PATCH v1 8/8] mm: Remove device private pages from the physical address space
config: s390-allnoconfig (https://download.01.org/0day-ci/archive/20260103/202601030906.9lgtN5Gq-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project f43d6834093b19baf79beda8c0337ab020ac5f17)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260103/202601030906.9lgtN5Gq-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/202601030906.9lgtN5Gq-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from arch/s390/purgatory/purgatory.c:10:
   In file included from include/linux/kexec.h:18:
   In file included from include/linux/vmcore_info.h:6:
   In file included from include/linux/elfcore.h:11:
   In file included from include/linux/ptrace.h:10:
   In file included from include/linux/pid_namespace.h:7:
   In file included from include/linux/mm.h:33:
>> include/linux/memremap.h:148:2: warning: field '' with variable sized type 'union dev_pagemap::(anonymous at include/linux/memremap.h:148:2)' not at the end of a struct or class is a GNU extension [-Wgnu-variable-sized-type-not-at-end]
     148 |         union {
         |         ^
   1 warning generated.


vim +148 include/linux/memremap.h

514caf23a70fd6 Christoph Hellwig   2019-06-26  113  
9476df7d80dfc4 Dan Williams        2016-01-15  114  /**
9476df7d80dfc4 Dan Williams        2016-01-15  115   * struct dev_pagemap - metadata for ZONE_DEVICE mappings
4b94ffdc4163ba Dan Williams        2016-01-15  116   * @altmap: pre-allocated/reserved memory for vmemmap allocations
5c2c2587b13235 Dan Williams        2016-01-15  117   * @ref: reference count that pins the devm_memremap_pages() mapping
b80892ca022e9e Christoph Hellwig   2021-10-28  118   * @done: completion for @ref
0c32c9f7a58e77 John Groves         2024-02-05  119   * @type: memory type: see MEMORY_* above in memremap.h
514caf23a70fd6 Christoph Hellwig   2019-06-26  120   * @flags: PGMAP_* flags to specify defailed behavior
c4386bd8ee3a92 Joao Martins        2022-01-14  121   * @vmemmap_shift: structural definition of how the vmemmap page metadata
c4386bd8ee3a92 Joao Martins        2022-01-14  122   *      is populated, specifically the metadata page order.
c4386bd8ee3a92 Joao Martins        2022-01-14  123   *	A zero value (default) uses base pages as the vmemmap metadata
c4386bd8ee3a92 Joao Martins        2022-01-14  124   *	representation. A bigger value will set up compound struct pages
c4386bd8ee3a92 Joao Martins        2022-01-14  125   *	of the requested order value.
1e240e8d4a7d92 Christoph Hellwig   2019-06-26  126   * @ops: method table
f894ddd5ff01d3 Christoph Hellwig   2020-03-16  127   * @owner: an opaque pointer identifying the entity that manages this
f894ddd5ff01d3 Christoph Hellwig   2020-03-16  128   *	instance.  Used by various helpers to make sure that no
f894ddd5ff01d3 Christoph Hellwig   2020-03-16  129   *	foreign ZONE_DEVICE memory is accessed.
0386df765967ce Jordan Niethe       2025-12-31  130   * @nr_range: number of ranges to be mapped. Always == 1 for
0386df765967ce Jordan Niethe       2025-12-31  131   *	MEMORY_DEVICE_PRIVATE.
0386df765967ce Jordan Niethe       2025-12-31  132   * @range: range to be mapped when nr_range == 1. Used as an output param for
0386df765967ce Jordan Niethe       2025-12-31  133   *	MEMORY_DEVICE_PRIVATE.
b7b3c01b191596 Dan Williams        2020-10-13  134   * @ranges: array of ranges to be mapped when nr_range > 1
0386df765967ce Jordan Niethe       2025-12-31  135   * @nr_pages: number of pages requested to be mapped for MEMORY_DEVICE_PRIVATE.
0386df765967ce Jordan Niethe       2025-12-31  136   * @pages: array of nr_pages initialized for MEMORY_DEVICE_PRIVATE.
9476df7d80dfc4 Dan Williams        2016-01-15  137   */
9476df7d80dfc4 Dan Williams        2016-01-15  138  struct dev_pagemap {
e7744aa25cffe2 Logan Gunthorpe     2017-12-29  139  	struct vmem_altmap altmap;
b80892ca022e9e Christoph Hellwig   2021-10-28  140  	struct percpu_ref ref;
24917f6b1041a7 Christoph Hellwig   2019-06-26  141  	struct completion done;
5042db43cc26f5 Jérôme Glisse       2017-09-08  142  	enum memory_type type;
514caf23a70fd6 Christoph Hellwig   2019-06-26  143  	unsigned int flags;
c4386bd8ee3a92 Joao Martins        2022-01-14  144  	unsigned long vmemmap_shift;
1e240e8d4a7d92 Christoph Hellwig   2019-06-26  145  	const struct dev_pagemap_ops *ops;
f894ddd5ff01d3 Christoph Hellwig   2020-03-16  146  	void *owner;
b7b3c01b191596 Dan Williams        2020-10-13  147  	int nr_range;
b7b3c01b191596 Dan Williams        2020-10-13 @148  	union {
b7b3c01b191596 Dan Williams        2020-10-13  149  		struct range range;
06919d226d0113 Gustavo A. R. Silva 2022-09-03  150  		DECLARE_FLEX_ARRAY(struct range, ranges);
b7b3c01b191596 Dan Williams        2020-10-13  151  	};
0386df765967ce Jordan Niethe       2025-12-31  152  	unsigned long nr_pages;
0386df765967ce Jordan Niethe       2025-12-31  153  	struct page *pages;
9476df7d80dfc4 Dan Williams        2016-01-15  154  };
9476df7d80dfc4 Dan Williams        2016-01-15  155  

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