[gourryinverse:scratch/gourry/managed_nodes/node_features_v6 26/44] mm/page_alloc.c:5121 prepare_alloc_pages() warn: bitwise AND condition is false here

BCC: [email protected]
CC: [email protected]
CC: Gregory Price <[email protected]>
TO: Gregory Price <[email protected]>

tree:   https://github.com/gourryinverse/linux scratch/gourry/managed_nodes/node_features_v6
head:   38c7f48162aa282dc6a9edfb7011378594057c10
commit: 7c721abf0da4daad0f380440d2dbcf4d3c5bc307 [26/44] mm/page_alloc: add a private-node zonelist family
:::::: branch date: 2 days ago
:::::: commit date: 2 days ago
config: i386-randconfig-r073-20260822 (https://download.01.org/0day-ci/archive/20260822/[email protected]/config)
compiler: clang version 22.1.3 (https://github.com/llvm/llvm-project e9846648fd6183ee6d8cbdb4502213fcf902a211)
smatch: v0.5.0-9187-g5189e3fb

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 <[email protected]>
| Reported-by: Dan Carpenter <[email protected]>
| Closes: https://lore.kernel.org/r/[email protected]/

smatch warnings:
mm/page_alloc.c:5121 prepare_alloc_pages() warn: bitwise AND condition is false here

vim +5121 mm/page_alloc.c

11e33f6a55ed78 Mel Gorman              2009-06-16  5100  
9cd7555875bb09 Mel Gorman              2017-02-24  5101  static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
04ec6264f28793 Vlastimil Babka         2017-07-06  5102  		int preferred_nid, nodemask_t *nodemask,
8e6a930bb3ea6a Matthew Wilcox (Oracle  2021-04-29  5103) 		struct alloc_context *ac, gfp_t *alloc_gfp,
9cd7555875bb09 Mel Gorman              2017-02-24  5104  		unsigned int *alloc_flags)
11e33f6a55ed78 Mel Gorman              2009-06-16  5105  {
97a225e69a1f88 Joonsoo Kim             2020-06-03  5106  	ac->highest_zoneidx = gfp_zone(gfp_mask);
7c721abf0da4da Gregory Price           2026-07-29  5107  	ac->zonelist = select_zonelist(preferred_nid, gfp_mask, *alloc_flags);
9cd7555875bb09 Mel Gorman              2017-02-24  5108  	ac->nodemask = nodemask;
01c0bfe061f309 Wei Yang                2020-06-03  5109  	ac->migratetype = gfp_migratetype(gfp_mask);
11e33f6a55ed78 Mel Gorman              2009-06-16  5110  
7c721abf0da4da Gregory Price           2026-07-29  5111  	/*
7c721abf0da4da Gregory Price           2026-07-29  5112  	 * The private *fallback* zonelist lists every private node and public
7c721abf0da4da Gregory Price           2026-07-29  5113  	 * memory, so it grants access without confining -- the nodemask is the
7c721abf0da4da Gregory Price           2026-07-29  5114  	 * confinement.  Refuse it without a nodemask rather than fall through to
7c721abf0da4da Gregory Price           2026-07-29  5115  	 * the cpuset_current_mems_allowed default below, which spans every granted
7c721abf0da4da Gregory Price           2026-07-29  5116  	 * private node and would let the allocation spill onto one the caller
7c721abf0da4da Gregory Price           2026-07-29  5117  	 * never named (an isolation break); fail safe to the public zonelist.
7c721abf0da4da Gregory Price           2026-07-29  5118  	 * __GFP_THISNODE selects ZONELIST_PRIVATE_NOFALLBACK (the target node's own
7c721abf0da4da Gregory Price           2026-07-29  5119  	 * zones only), which is self-confining, so no nodemask is required there.
7c721abf0da4da Gregory Price           2026-07-29  5120  	 */
7c721abf0da4da Gregory Price           2026-07-29 @5121  	if ((*alloc_flags & ALLOC_ZONELIST_PRIVATE) && !nodemask &&
7c721abf0da4da Gregory Price           2026-07-29  5122  	    !(gfp_mask & __GFP_THISNODE)) {
7c721abf0da4da Gregory Price           2026-07-29  5123  		WARN_ON_ONCE(1);
7c721abf0da4da Gregory Price           2026-07-29  5124  		*alloc_flags &= ~ALLOC_ZONELIST_PRIVATE;
7c721abf0da4da Gregory Price           2026-07-29  5125  		ac->zonelist = select_zonelist(preferred_nid, gfp_mask, *alloc_flags);
7c721abf0da4da Gregory Price           2026-07-29  5126  	}
7c721abf0da4da Gregory Price           2026-07-29  5127  
682a3385e7734f Mel Gorman              2016-05-19  5128  	if (cpusets_enabled()) {
8e6a930bb3ea6a Matthew Wilcox (Oracle  2021-04-29  5129) 		*alloc_gfp |= __GFP_HARDWALL;
182f3d7a02fddd Muchun Song             2020-08-06  5130  		/*
182f3d7a02fddd Muchun Song             2020-08-06  5131  		 * When we are in the interrupt context, it is irrelevant
182f3d7a02fddd Muchun Song             2020-08-06  5132  		 * to the current task context. It means that any node ok.
182f3d7a02fddd Muchun Song             2020-08-06  5133  		 */
88dc6f208829cf Vasily Averin           2021-09-02  5134  		if (in_task() && !ac->nodemask)
9cd7555875bb09 Mel Gorman              2017-02-24  5135  			ac->nodemask = &cpuset_current_mems_allowed;
5104782011a12b Vlastimil Babka         2017-02-24  5136  		else
5104782011a12b Vlastimil Babka         2017-02-24  5137  			*alloc_flags |= ALLOC_CPUSET;
682a3385e7734f Mel Gorman              2016-05-19  5138  	}
682a3385e7734f Mel Gorman              2016-05-19  5139  
446ec83805ddaa Simona Vetter           2022-06-05  5140  	might_alloc(gfp_mask);
11e33f6a55ed78 Mel Gorman              2009-06-16  5141  
97769a53f117e2 Alexei Starovoitov      2025-02-21  5142  	/*
97769a53f117e2 Alexei Starovoitov      2025-02-21  5143  	 * Don't invoke should_fail logic, since it may call
97769a53f117e2 Alexei Starovoitov      2025-02-21  5144  	 * get_random_u32() and printk() which need to spin_lock.
97769a53f117e2 Alexei Starovoitov      2025-02-21  5145  	 */
03eaf4c4451229 Brendan Jackman         2026-07-03  5146  	if (!(*alloc_flags & ALLOC_NOLOCK) &&
97769a53f117e2 Alexei Starovoitov      2025-02-21  5147  	    should_fail_alloc_page(gfp_mask, order))
9cd7555875bb09 Mel Gorman              2017-02-24  5148  		return false;
11e33f6a55ed78 Mel Gorman              2009-06-16  5149  
5df11ba0eb5ae3 Brendan Jackman         2026-07-03  5150  	*alloc_flags |= alloc_flags_cma(gfp_mask);
d883c6cf3b39f1 Joonsoo Kim             2018-05-23  5151  
c9ab0c4fbeb020 Mel Gorman              2015-11-06  5152  	/* Dirty zone balancing only done in the fast path */
9cd7555875bb09 Mel Gorman              2017-02-24  5153  	ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
c9ab0c4fbeb020 Mel Gorman              2015-11-06  5154  
e46e7b77c9096e Mel Gorman              2016-06-03  5155  	/*
e46e7b77c9096e Mel Gorman              2016-06-03  5156  	 * The preferred zone is used for statistics but crucially it is
e46e7b77c9096e Mel Gorman              2016-06-03  5157  	 * also used as the starting point for the zonelist iterator. It
e46e7b77c9096e Mel Gorman              2016-06-03  5158  	 * may get reset for allocations that ignore memory policies.
e46e7b77c9096e Mel Gorman              2016-06-03  5159  	 */
9cd7555875bb09 Mel Gorman              2017-02-24  5160  	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
97a225e69a1f88 Joonsoo Kim             2020-06-03  5161  					ac->highest_zoneidx, ac->nodemask);
a0622d05374b61 Mateusz Nosek           2020-10-13  5162  
a0622d05374b61 Mateusz Nosek           2020-10-13  5163  	return true;
9cd7555875bb09 Mel Gorman              2017-02-24  5164  }
9cd7555875bb09 Mel Gorman              2017-02-24  5165  

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