https://github.com/ClangBuiltLinux/linux/issues/1868

foo.txt

mm/vmalloc.c:1575:12: warning: Assigned value is garbage or undefined [clang-analyzer-core.uninitialized.Assign]
 1575 |         if (va && __this_cpu_cmpxchg(ne_fit_preload_node, NULL, va))
      |                   ^
./include/linux/percpu-defs.h:475:2: note: expanded from macro '__this_cpu_cmpxchg'
  475 |         raw_cpu_cmpxchg(pcp, oval, nval);                               \
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/percpu-defs.h:416:2: note: expanded from macro 'raw_cpu_cmpxchg'
  416 |         __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/percpu-defs.h:339:24: note: expanded from macro '__pcpu_size_call_return2'
  339 |         case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break;    \
      |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: expanded from here
./include/asm-generic/percpu.h:362:2: note: expanded from macro 'raw_cpu_cmpxchg_8'
  362 |         raw_cpu_generic_cmpxchg(pcp, oval, nval)
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/asm-generic/percpu.h:119:2: note: expanded from macro 'raw_cpu_generic_cmpxchg'
  119 |         raw_cpu_generic_try_cmpxchg(pcp, &__old, nval);                 \
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/asm-generic/percpu.h:104:28: note: expanded from macro 'raw_cpu_generic_try_cmpxchg'
  104 |         typeof(pcp) __val = *__p, __old = *(ovalp);                     \
      |                                   ^       ~~~~~~~~
mm/vmalloc.c:1570:7: note: Loop condition is false.  Exiting loop
 1570 |         if (!this_cpu_read(ne_fit_preload_node))
      |              ^
./include/linux/percpu-defs.h:489:29: note: expanded from macro 'this_cpu_read'
  489 | #define this_cpu_read(pcp)              __pcpu_size_call_return(this_cpu_read_, pcp)
      |                                         ^
./include/linux/percpu-defs.h:319:2: note: expanded from macro '__pcpu_size_call_return'
  319 |         __verify_pcpu_ptr(&(variable));                                 \
      |         ^
./include/linux/percpu-defs.h:217:37: note: expanded from macro '__verify_pcpu_ptr'
  217 | #define __verify_pcpu_ptr(ptr)                                          \
      |                                                                         ^
mm/vmalloc.c:1570:7: note: Control jumps to 'case 8:'  at line 1570
 1570 |         if (!this_cpu_read(ne_fit_preload_node))
      |              ^
./include/linux/percpu-defs.h:489:29: note: expanded from macro 'this_cpu_read'
  489 | #define this_cpu_read(pcp)              __pcpu_size_call_return(this_cpu_read_, pcp)
      |                                         ^
./include/linux/percpu-defs.h:320:2: note: expanded from macro '__pcpu_size_call_return'
  320 |         switch(sizeof(variable)) {                                      \
      |         ^
mm/vmalloc.c:1570:7: note: Loop condition is false.  Exiting loop
 1570 |         if (!this_cpu_read(ne_fit_preload_node))
      |              ^
./include/linux/percpu-defs.h:489:29: note: expanded from macro 'this_cpu_read'
  489 | #define this_cpu_read(pcp)              __pcpu_size_call_return(this_cpu_read_, pcp)
      |                                         ^
./include/linux/percpu-defs.h:324:23: note: expanded from macro '__pcpu_size_call_return'
  324 |         case 8: pscr_ret__ = stem##8(variable); break;                  \
      |                              ^
note: expanded from here
./arch/arm64/include/asm/percpu.h:172:2: note: expanded from macro 'this_cpu_read_8'
  172 |         _pcp_protect_return(__percpu_read_64, pcp)
      |         ^
./arch/arm64/include/asm/percpu.h:159:2: note: expanded from macro '_pcp_protect_return'
  159 |         preempt_disable_notrace();                                      \
      |         ^
./include/linux/preempt.h:254:35: note: expanded from macro 'preempt_disable_notrace'
  254 | #define preempt_disable_notrace() \
      |                                   ^
mm/vmalloc.c:1570:7: note: Loop condition is false.  Exiting loop
 1570 |         if (!this_cpu_read(ne_fit_preload_node))
      |              ^
./include/linux/percpu-defs.h:489:29: note: expanded from macro 'this_cpu_read'
  489 | #define this_cpu_read(pcp)              __pcpu_size_call_return(this_cpu_read_, pcp)
      |                                         ^
./include/linux/percpu-defs.h:324:23: note: expanded from macro '__pcpu_size_call_return'
  324 |         case 8: pscr_ret__ = stem##8(variable); break;                  \
      |                              ^
note: expanded from here
./arch/arm64/include/asm/percpu.h:172:2: note: expanded from macro 'this_cpu_read_8'
  172 |         _pcp_protect_return(__percpu_read_64, pcp)
      |         ^
./arch/arm64/include/asm/percpu.h:160:29: note: expanded from macro '_pcp_protect_return'
  160 |         __retval = (typeof(pcp))op(raw_cpu_ptr(&(pcp)), ##args);        \
      |                                    ^
./include/linux/percpu-defs.h:241:2: note: expanded from macro 'raw_cpu_ptr'
  241 |         __verify_pcpu_ptr(ptr);                                         \
      |         ^
./include/linux/percpu-defs.h:217:37: note: expanded from macro '__verify_pcpu_ptr'
  217 | #define __verify_pcpu_ptr(ptr)                                          \
      |                                                                         ^
mm/vmalloc.c:1570:7: note: Taking true branch
 1570 |         if (!this_cpu_read(ne_fit_preload_node))
      |              ^
./include/linux/percpu-defs.h:489:29: note: expanded from macro 'this_cpu_read'
  489 | #define this_cpu_read(pcp)              __pcpu_size_call_return(this_cpu_read_, pcp)
      |                                         ^
./include/linux/percpu-defs.h:324:23: note: expanded from macro '__pcpu_size_call_return'
  324 |         case 8: pscr_ret__ = stem##8(variable); break;                  \
      |                              ^
note: expanded from here
./arch/arm64/include/asm/percpu.h:172:2: note: expanded from macro 'this_cpu_read_8'
  172 |         _pcp_protect_return(__percpu_read_64, pcp)
      |         ^
./arch/arm64/include/asm/percpu.h:161:2: note: expanded from macro '_pcp_protect_return'
  161 |         preempt_enable_notrace();                                       \
      |         ^
./include/linux/preempt.h:228:2: note: expanded from macro 'preempt_enable_notrace'
  228 |         if (unlikely(__preempt_count_dec_and_test())) \
      |         ^
mm/vmalloc.c:1570:7: note: Loop condition is false.  Exiting loop
 1570 |         if (!this_cpu_read(ne_fit_preload_node))
      |              ^
./include/linux/percpu-defs.h:489:29: note: expanded from macro 'this_cpu_read'
  489 | #define this_cpu_read(pcp)              __pcpu_size_call_return(this_cpu_read_, pcp)
      |                                         ^
./include/linux/percpu-defs.h:324:23: note: expanded from macro '__pcpu_size_call_return'
  324 |         case 8: pscr_ret__ = stem##8(variable); break;                  \
      |                              ^
note: expanded from here
./arch/arm64/include/asm/percpu.h:172:2: note: expanded from macro 'this_cpu_read_8'
  172 |         _pcp_protect_return(__percpu_read_64, pcp)
      |         ^
./arch/arm64/include/asm/percpu.h:161:2: note: expanded from macro '_pcp_protect_return'
  161 |         preempt_enable_notrace();                                       \
      |         ^
./include/linux/preempt.h:225:34: note: expanded from macro 'preempt_enable_notrace'
  225 | #define preempt_enable_notrace() \
      |                                  ^
mm/vmalloc.c:1570:7: note:  Execution continues on line 1570
 1570 |         if (!this_cpu_read(ne_fit_preload_node))
      |              ^
./include/linux/percpu-defs.h:489:29: note: expanded from macro 'this_cpu_read'
  489 | #define this_cpu_read(pcp)              __pcpu_size_call_return(this_cpu_read_, pcp)
      |                                         ^
./include/linux/percpu-defs.h:324:42: note: expanded from macro '__pcpu_size_call_return'
  324 |         case 8: pscr_ret__ = stem##8(variable); break;                  \
      |                                                 ^
mm/vmalloc.c:1570:6: note: Assuming the condition is true
 1570 |         if (!this_cpu_read(ne_fit_preload_node))
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/vmalloc.c:1570:2: note: Taking true branch
 1570 |         if (!this_cpu_read(ne_fit_preload_node))
      |         ^
mm/vmalloc.c:1575:6: note: Assuming 'va' is non-null
 1575 |         if (va && __this_cpu_cmpxchg(ne_fit_preload_node, NULL, va))
      |             ^~
mm/vmalloc.c:1575:6: note: Left side of '&&' is true
mm/vmalloc.c:1575:12: note: Loop condition is false.  Exiting loop
 1575 |         if (va && __this_cpu_cmpxchg(ne_fit_preload_node, NULL, va))
      |                   ^
./include/linux/percpu-defs.h:475:2: note: expanded from macro '__this_cpu_cmpxchg'
  475 |         raw_cpu_cmpxchg(pcp, oval, nval);                               \
      |         ^
./include/linux/percpu-defs.h:416:2: note: expanded from macro 'raw_cpu_cmpxchg'
  416 |         __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
      |         ^
./include/linux/percpu-defs.h:334:2: note: expanded from macro '__pcpu_size_call_return2'
  334 |         __verify_pcpu_ptr(&(variable));                                 \
      |         ^
./include/linux/percpu-defs.h:217:37: note: expanded from macro '__verify_pcpu_ptr'
  217 | #define __verify_pcpu_ptr(ptr)                                          \
      |                                                                         ^
mm/vmalloc.c:1575:12: note: Control jumps to 'case 8:'  at line 1575
 1575 |         if (va && __this_cpu_cmpxchg(ne_fit_preload_node, NULL, va))
      |                   ^
./include/linux/percpu-defs.h:475:2: note: expanded from macro '__this_cpu_cmpxchg'
  475 |         raw_cpu_cmpxchg(pcp, oval, nval);                               \
      |         ^
./include/linux/percpu-defs.h:416:2: note: expanded from macro 'raw_cpu_cmpxchg'
  416 |         __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
      |         ^
./include/linux/percpu-defs.h:335:2: note: expanded from macro '__pcpu_size_call_return2'
  335 |         switch(sizeof(variable)) {                                      \
      |         ^
mm/vmalloc.c:1575:12: note: Loop condition is false.  Exiting loop
 1575 |         if (va && __this_cpu_cmpxchg(ne_fit_preload_node, NULL, va))
      |                   ^
./include/linux/percpu-defs.h:475:2: note: expanded from macro '__this_cpu_cmpxchg'
  475 |         raw_cpu_cmpxchg(pcp, oval, nval);                               \
      |         ^
./include/linux/percpu-defs.h:416:2: note: expanded from macro 'raw_cpu_cmpxchg'
  416 |         __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
      |         ^
./include/linux/percpu-defs.h:339:24: note: expanded from macro '__pcpu_size_call_return2'
  339 |         case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break;    \
      |                               ^
note: expanded from here
./include/asm-generic/percpu.h:362:2: note: expanded from macro 'raw_cpu_cmpxchg_8'
  362 |         raw_cpu_generic_cmpxchg(pcp, oval, nval)
      |         ^
./include/asm-generic/percpu.h:119:2: note: expanded from macro 'raw_cpu_generic_cmpxchg'
  119 |         raw_cpu_generic_try_cmpxchg(pcp, &__old, nval);                 \
      |         ^
./include/asm-generic/percpu.h:103:21: note: expanded from macro 'raw_cpu_generic_try_cmpxchg'
  103 |         typeof(pcp) *__p = raw_cpu_ptr(&(pcp));                         \
      |                            ^
./include/linux/percpu-defs.h:241:2: note: expanded from macro 'raw_cpu_ptr'
  241 |         __verify_pcpu_ptr(ptr);                                         \
      |         ^
./include/linux/percpu-defs.h:217:37: note: expanded from macro '__verify_pcpu_ptr'
  217 | #define __verify_pcpu_ptr(ptr)                                          \
      |                                                                         ^
mm/vmalloc.c:1575:12: note: Assigned value is garbage or undefined
 1575 |         if (va && __this_cpu_cmpxchg(ne_fit_preload_node, NULL, va))
      |                   ^
./include/linux/percpu-defs.h:475:2: note: expanded from macro '__this_cpu_cmpxchg'
  475 |         raw_cpu_cmpxchg(pcp, oval, nval);                               \
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/percpu-defs.h:416:2: note: expanded from macro 'raw_cpu_cmpxchg'
  416 |         __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/percpu-defs.h:339:24: note: expanded from macro '__pcpu_size_call_return2'
  339 |         case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break;    \
      |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: expanded from here
./include/asm-generic/percpu.h:362:2: note: expanded from macro 'raw_cpu_cmpxchg_8'
  362 |         raw_cpu_generic_cmpxchg(pcp, oval, nval)
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/asm-generic/percpu.h:119:2: note: expanded from macro 'raw_cpu_generic_cmpxchg'
  119 |         raw_cpu_generic_try_cmpxchg(pcp, &__old, nval);                 \
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/asm-generic/percpu.h:104:28: note: expanded from macro 'raw_cpu_generic_try_cmpxchg'
  104 |         typeof(pcp) __val = *__p, __old = *(ovalp);                     \
      |                                   ^       ~~~~~~~~