Re: [RFC PATCH 6/6] mm: Remove device private pages from the physical address space

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

Hi Jordan,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

[auto build test WARNING on e1afacb68573c3cd0a3785c6b0508876cd3423bc]

url:    https://github.com/intel-lab-lkp/linux/commits/Jordan-Niethe/mm-hmm-Add-flag-to-track-device-private-PFNs/20251128-124406
base:   e1afacb68573c3cd0a3785c6b0508876cd3423bc
patch link:    https://lore.kernel.org/r/20251128044146.80050-7-jniethe%40nvidia.com
patch subject: [RFC PATCH 6/6] mm: Remove device private pages from the physical address space
config: s390-allnoconfig (https://download.01.org/0day-ci/archive/20251128/202511281438.x8ovUgeA-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project b3428bb966f1de8aa48375ffee0eba04ede133b7)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251128/202511281438.x8ovUgeA-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/202511281438.x8ovUgeA-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:142:2: warning: field '' with variable sized type 'union dev_pagemap::(anonymous at include/linux/memremap.h:142:2)' not at the end of a struct or class is a GNU extension [-Wgnu-variable-sized-type-not-at-end]
     142 |         union {
         |         ^
   1 warning generated.


vim +142 include/linux/memremap.h

514caf23a70fd69 Christoph Hellwig   2019-06-26  107  
9476df7d80dfc42 Dan Williams        2016-01-15  108  /**
9476df7d80dfc42 Dan Williams        2016-01-15  109   * struct dev_pagemap - metadata for ZONE_DEVICE mappings
4b94ffdc4163bae Dan Williams        2016-01-15  110   * @altmap: pre-allocated/reserved memory for vmemmap allocations
5c2c2587b13235b Dan Williams        2016-01-15  111   * @ref: reference count that pins the devm_memremap_pages() mapping
b80892ca022e9eb Christoph Hellwig   2021-10-28  112   * @done: completion for @ref
0c32c9f7a58e773 John Groves         2024-02-05  113   * @type: memory type: see MEMORY_* above in memremap.h
514caf23a70fd69 Christoph Hellwig   2019-06-26  114   * @flags: PGMAP_* flags to specify defailed behavior
c4386bd8ee3a921 Joao Martins        2022-01-14  115   * @vmemmap_shift: structural definition of how the vmemmap page metadata
c4386bd8ee3a921 Joao Martins        2022-01-14  116   *      is populated, specifically the metadata page order.
c4386bd8ee3a921 Joao Martins        2022-01-14  117   *	A zero value (default) uses base pages as the vmemmap metadata
c4386bd8ee3a921 Joao Martins        2022-01-14  118   *	representation. A bigger value will set up compound struct pages
c4386bd8ee3a921 Joao Martins        2022-01-14  119   *	of the requested order value.
1e240e8d4a7d922 Christoph Hellwig   2019-06-26  120   * @ops: method table
f894ddd5ff01d3b Christoph Hellwig   2020-03-16  121   * @owner: an opaque pointer identifying the entity that manages this
f894ddd5ff01d3b Christoph Hellwig   2020-03-16  122   *	instance.  Used by various helpers to make sure that no
f894ddd5ff01d3b Christoph Hellwig   2020-03-16  123   *	foreign ZONE_DEVICE memory is accessed.
31ff70a0ab1c747 Jordan Niethe       2025-11-28  124   * @nr_range: number of ranges to be mapped. Always == 1 for
31ff70a0ab1c747 Jordan Niethe       2025-11-28  125   *	MEMORY_DEVICE_PRIVATE.
31ff70a0ab1c747 Jordan Niethe       2025-11-28  126   * @range: range to be mapped when nr_range == 1. Used as an output param for
31ff70a0ab1c747 Jordan Niethe       2025-11-28  127   *	MEMORY_DEVICE_PRIVATE.
b7b3c01b191596d Dan Williams        2020-10-13  128   * @ranges: array of ranges to be mapped when nr_range > 1
31ff70a0ab1c747 Jordan Niethe       2025-11-28  129   * @nr_pages: number of pages requested to be mapped for MEMORY_DEVICE_PRIVATE.
31ff70a0ab1c747 Jordan Niethe       2025-11-28  130   * @pages: array of nr_pages initialized for MEMORY_DEVICE_PRIVATE.
9476df7d80dfc42 Dan Williams        2016-01-15  131   */
9476df7d80dfc42 Dan Williams        2016-01-15  132  struct dev_pagemap {
e7744aa25cffe26 Logan Gunthorpe     2017-12-29  133  	struct vmem_altmap altmap;
b80892ca022e9eb Christoph Hellwig   2021-10-28  134  	struct percpu_ref ref;
24917f6b1041a73 Christoph Hellwig   2019-06-26  135  	struct completion done;
5042db43cc26f51 Jérôme Glisse       2017-09-08  136  	enum memory_type type;
514caf23a70fd69 Christoph Hellwig   2019-06-26  137  	unsigned int flags;
c4386bd8ee3a921 Joao Martins        2022-01-14  138  	unsigned long vmemmap_shift;
1e240e8d4a7d922 Christoph Hellwig   2019-06-26  139  	const struct dev_pagemap_ops *ops;
f894ddd5ff01d3b Christoph Hellwig   2020-03-16  140  	void *owner;
b7b3c01b191596d Dan Williams        2020-10-13  141  	int nr_range;
b7b3c01b191596d Dan Williams        2020-10-13 @142  	union {
b7b3c01b191596d Dan Williams        2020-10-13  143  		struct range range;
06919d226d01132 Gustavo A. R. Silva 2022-09-03  144  		DECLARE_FLEX_ARRAY(struct range, ranges);
b7b3c01b191596d Dan Williams        2020-10-13  145  	};
31ff70a0ab1c747 Jordan Niethe       2025-11-28  146  	unsigned long nr_pages;
31ff70a0ab1c747 Jordan Niethe       2025-11-28  147  	struct page *pages;
9476df7d80dfc42 Dan Williams        2016-01-15  148  };
9476df7d80dfc42 Dan Williams        2016-01-15  149  

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