Tom reported this finding from clang 10's static analysis [1]. Due to the way the code is written, it will always see a successful loop iteration. Instead of setting an initial value, check that it was set instead with BUG_ON() because 0 units per allocation is bogus. [1] https://lore.kernel.org/lkml/20210515180817.1751084-1-trix@xxxxxxxxxx/ Reported-by: Tom Rix <trix@xxxxxxxxxx> Signed-off-by: Dennis Zhou <dennis@xxxxxxxxxx> --- Sorry this hasn't been my highest priority. I'll apply this shortly to for-5.14. mm/percpu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/percpu.c b/mm/percpu.c index e7b9ca82e9aa..6667dfa0fcec 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -2888,6 +2888,7 @@ static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info( * Related to atom_size, which could be much larger than the unit_size. */ last_allocs = INT_MAX; + best_upa = 0; for (upa = max_upa; upa; upa--) { int allocs = 0, wasted = 0; @@ -2914,6 +2915,7 @@ static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info( last_allocs = allocs; best_upa = upa; } + BUG_ON(!best_upa); upa = best_upa; /* allocate and fill alloc_info */ -- 2.32.0.272.g935e593368-goog
