* [davidhildenbrand:mm_id 9/17] include/linux/rmap.h:203:50: warning: result of comparison of constant -1 with expression of type 'mm_mapcount_t' (aka 'unsigned short') is always true
@ 2024-12-14 17:37 kernel test robot
0 siblings, 0 replies; only message in thread
From: kernel test robot @ 2024-12-14 17:37 UTC (permalink / raw)
To: David Hildenbrand; +Cc: llvm, oe-kbuild-all
tree: https://github.com/davidhildenbrand/linux mm_id
head: 4450db81511279bd8a750c7f19e7d02dd6661c05
commit: 308ab7ba6c2cfcd257b50194361b89b82a4c2346 [9/17] mm/rmap: initial MM owner tracking for large folios (!hugetlb)
config: i386-buildonly-randconfig-004-20241214 (https://download.01.org/0day-ci/archive/20241215/202412150157.TEmGpTYe-lkp@intel.com/config)
compiler: clang version 19.1.3 (https://github.com/llvm/llvm-project ab51eccf88f5321e7c60591c5546b254b6afab99)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241215/202412150157.TEmGpTYe-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/202412150157.TEmGpTYe-lkp@intel.com/
All warnings (new ones prefixed by >>):
In file included from kernel/fork.c:46:
include/linux/mm_inline.h:47:41: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
47 | __mod_lruvec_state(lruvec, NR_LRU_BASE + lru, nr_pages);
| ~~~~~~~~~~~ ^ ~~~
include/linux/mm_inline.h:49:22: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
49 | NR_ZONE_LRU_BASE + lru, nr_pages);
| ~~~~~~~~~~~~~~~~ ^ ~~~
In file included from kernel/fork.c:71:
>> include/linux/rmap.h:203:50: warning: result of comparison of constant -1 with expression of type 'mm_mapcount_t' (aka 'unsigned short') is always true [-Wtautological-constant-out-of-range-compare]
203 | VM_WARN_ON_ONCE(folio->_mm_id_data.mapcount[0] != -1);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~
include/linux/mmdebug.h:92:50: note: expanded from macro 'VM_WARN_ON_ONCE'
92 | #define VM_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond)
| ^~~~
include/asm-generic/bug.h:111:25: note: expanded from macro 'WARN_ON_ONCE'
111 | int __ret_warn_on = !!(condition); \
| ^~~~~~~~~
In file included from kernel/fork.c:71:
include/linux/rmap.h:204:50: warning: result of comparison of constant -1 with expression of type 'mm_mapcount_t' (aka 'unsigned short') is always true [-Wtautological-constant-out-of-range-compare]
204 | VM_WARN_ON_ONCE(folio->_mm_id_data.mapcount[1] != -1);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~
include/linux/mmdebug.h:92:50: note: expanded from macro 'VM_WARN_ON_ONCE'
92 | #define VM_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond)
| ^~~~
include/asm-generic/bug.h:111:25: note: expanded from macro 'WARN_ON_ONCE'
111 | int __ret_warn_on = !!(condition); \
| ^~~~~~~~~
In file included from kernel/fork.c:71:
>> include/linux/rmap.h:244:38: warning: result of comparison of constant -1 with expression of type 'mm_mapcount_t' (aka 'unsigned short') is always false [-Wtautological-constant-out-of-range-compare]
244 | if (folio->_mm_id_data.mapcount[0] == -1) {
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~
include/linux/rmap.h:250:51: warning: result of comparison of constant -1 with expression of type 'mm_mapcount_t' (aka 'unsigned short') is always true [-Wtautological-constant-out-of-range-compare]
250 | VM_WARN_ON_ONCE(folio->_mm_id_data.mapcount[1] != -1);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~
include/linux/mmdebug.h:92:50: note: expanded from macro 'VM_WARN_ON_ONCE'
92 | #define VM_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond)
| ^~~~
include/asm-generic/bug.h:111:25: note: expanded from macro 'WARN_ON_ONCE'
111 | int __ret_warn_on = !!(condition); \
| ^~~~~~~~~
6 warnings generated.
vim +203 include/linux/rmap.h
194
195 static __always_inline void folio_set_large_mapcount(struct folio *folio,
196 int mapcount, struct vm_area_struct *vma)
197 {
198 __folio_large_mapcount_sanity_checks(folio, mapcount, vma->vm_mm->mm_id);
199
200 /* Note: mapcounts start at -1. */
201 atomic_set(&folio->_large_mapcount, mapcount - 1);
202 if (IS_ENABLED(CONFIG_64BIT) || folio_large_order(folio) > 1) {
> 203 VM_WARN_ON_ONCE(folio->_mm_id_data.mapcount[0] != -1);
204 VM_WARN_ON_ONCE(folio->_mm_id_data.mapcount[1] != -1);
205 folio->_mm_id_data.mapcount[0] = mapcount - 1;
206 folio->_mm_id_data.id[0] = vma->vm_mm->mm_id;
207 }
208 }
209
210 static __always_inline void folio_add_large_mapcount(struct folio *folio,
211 int diff, struct vm_area_struct *vma)
212 {
213 bool was_exclusive, maybe_shared = false;
214 const mm_id_t mm_id = vma->vm_mm->mm_id;
215 int new_mapcount_val;
216
217 folio_lock_large_mapcount(folio);
218 __folio_large_mapcount_sanity_checks(folio, diff, mm_id);
219
220 new_mapcount_val = atomic_read(&folio->_large_mapcount) + diff;
221 atomic_set(&folio->_large_mapcount, new_mapcount_val);
222
223 /* order-1 folios on 32bit are maybe share if it wasn't unmapped. */
224 if (!IS_ENABLED(CONFIG_64BIT) && folio_large_order(folio) == 1) {
225 if (new_mapcount_val != diff - 1)
226 folio_set_large_maybe_mapped_shared(folio);
227 goto unlock;
228 }
229
230 was_exclusive = !folio_test_large_maybe_mapped_shared(folio);
231 if (folio->_mm_id_data.id[0] == mm_id) {
232 folio->_mm_id_data.mapcount[0] += diff;
233 maybe_shared = folio->_mm_id_data.mapcount[0] ^ new_mapcount_val;
234 } else if (folio->_mm_id_data.id[1] == mm_id) {
235 folio->_mm_id_data.mapcount[1] += diff;
236 maybe_shared = folio->_mm_id_data.mapcount[1] ^ new_mapcount_val;
237 } else if (was_exclusive) {
238 /*
239 * An MM can only take over a slot if there are no mappings yet
240 * or if all mappings belong to one slot ("exclusive"). This
241 * makes sure that mappings of a MM are not partially tracked in
242 * a slot.
243 */
> 244 if (folio->_mm_id_data.mapcount[0] == -1) {
245 folio->_mm_id_data.id[0] = mm_id;
246 /* Note: mapcounts start at -1. */
247 folio->_mm_id_data.mapcount[0] = diff - 1;
248 maybe_shared = folio->_mm_id_data.mapcount[0] ^ new_mapcount_val;
249 } else {
250 VM_WARN_ON_ONCE(folio->_mm_id_data.mapcount[1] != -1);
251 folio->_mm_id_data.id[1] = mm_id;
252 /* Note: mapcounts start at -1. */
253 folio->_mm_id_data.mapcount[1] = diff - 1;
254 maybe_shared = true;
255 }
256 }
257
258 if (maybe_shared && was_exclusive)
259 folio_set_large_maybe_mapped_shared(folio);
260 unlock:
261 folio_unlock_large_mapcount(folio);
262 }
263 #define folio_inc_large_mapcount(folio, vma) \
264 folio_add_large_mapcount(folio, 1, vma)
265
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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