Hi Ingo, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git tmp.tmp2 head: adcceb5eb7aee38e4a9c15bdf599655f0e1b1324 commit: 880b182db2f9eaa03034f29e0ba191fcffc4e7f5 [242/364] sched/headers, kthread: Remove <linux/sched.h> from <linux/kthread.h> config: x86_64-rhel-8.3 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=88... git remote add tip https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git git fetch --no-tags tip tmp.tmp2 git checkout 880b182db2f9eaa03034f29e0ba191fcffc4e7f5 # save the attached .config to linux build tree make W=1 ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): In file included from include/linux/srcu.h:20, from include/linux/notifier.h:16, from arch/x86/include/asm/uprobes.h:13, from include/linux/uprobes.h:49, from include/linux/mm_types.h:14, from include/linux/mmzone.h:21, from include/linux/gfp.h:7, from include/linux/mm.h:12, from include/linux/ring_buffer.h:5, from kernel/trace/ring_buffer_benchmark.c:7: include/linux/rcuwait.h: In function 'rcuwait_active': include/linux/rcupdate.h:364:9: error: dereferencing pointer to incomplete type 'struct task_struct' 364 | typeof(*p) *_________p1 = (typeof(*p) *__force)READ_ONCE(p); \ | ^ include/linux/rcupdate.h:474:31: note: in expansion of macro '__rcu_access_pointer' 474 | #define rcu_access_pointer(p) __rcu_access_pointer((p), __rcu) | ^~~~~~~~~~~~~~~~~~~~ include/linux/rcuwait.h:33:11: note: in expansion of macro 'rcu_access_pointer' 33 | return !!rcu_access_pointer(w->task); | ^~~~~~~~~~~~~~~~~~ kernel/trace/ring_buffer_benchmark.c: At top level: 45 | static int producer_nice = MAX_NICE; | ^~~~~~~~ kernel/trace/ring_buffer_benchmark.c: In function 'ring_buffer_consumer': 219 | set_current_state(TASK_INTERRUPTIBLE); | ^~~~~~~~~~~~~~~~~ | set_current_groups 223 | schedule(); | ^~~~~~~~ 225 | __set_current_state(TASK_RUNNING); | ^~~~~~~~~~~~~~~~~~~ kernel/trace/ring_buffer_benchmark.c: In function 'ring_buffer_producer': 268 | wake_up_process(consumer); | ^~~~~~~~~~~~~~~ | wake_up_poll kernel/trace/ring_buffer_benchmark.c:281:4: error: implicit declaration of function 'cond_resched'; did you mean 'should_resched'? [-Werror=implicit-function-declaration] 281 | cond_resched(); | ^~~~~~~~~~~~ | should_resched kernel/trace/ring_buffer_benchmark.c: In function 'ring_buffer_producer_thread': 419 | schedule_timeout(HZ * SLEEP_TIME); | ^~~~~~~~~~~~~~~~ | schedule_work kernel/trace/ring_buffer_benchmark.c: In function 'ring_buffer_benchmark_init': 459 | sched_set_fifo(consumer); | ^~~~~~~~~~~~~~ 461 | sched_set_fifo_low(consumer); | ^~~~~~~~~~~~~~~~~~ 463 | set_user_nice(consumer, consumer_nice); | ^~~~~~~~~~~~~ | seq_user_ns In file included from include/linux/uaccess.h:11, from arch/x86/include/asm/fpu/xstate.h:5, from arch/x86/include/asm/pgtable.h:26, from include/linux/pgtable.h:6, from include/linux/mm.h:35, from include/linux/ring_buffer.h:5, from kernel/trace/ring_buffer_benchmark.c:7: kernel/trace/ring_buffer_benchmark.c: At top level: arch/x86/include/asm/uaccess.h:46:20: warning: 'pagefault_disabled' used but never defined 46 | static inline bool pagefault_disabled(void); | ^~~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors -- In file included from lib/kunit/try-catch.c:13: lib/kunit/try-catch.c: In function 'kunit_try_catch_run': 55 | wake_up_process(__k); \ | ^~~~~~~~~~~~~~~ lib/kunit/try-catch.c:68:16: note: in expansion of macro 'kthread_run' 68 | task_struct = kthread_run(kunit_generic_run_threadfn_adapter, | ^~~~~~~~~~~ cc1: some warnings being treated as errors vim +55 include/linux/kthread.h ac687e6e8c2618 Peter Zijlstra 2021-01-12 40 ^1da177e4c3f41 Linus Torvalds 2005-04-16 41 /** 9e37bd301ee130 Randy Dunlap 2006-06-25 42 * kthread_run - create and wake a thread. ^1da177e4c3f41 Linus Torvalds 2005-04-16 43 * @threadfn: the function to run until signal_pending(current). ^1da177e4c3f41 Linus Torvalds 2005-04-16 44 * @data: data ptr for @threadfn. ^1da177e4c3f41 Linus Torvalds 2005-04-16 45 * @namefmt: printf-style name for the thread. ^1da177e4c3f41 Linus Torvalds 2005-04-16 46 * ^1da177e4c3f41 Linus Torvalds 2005-04-16 47 * Description: Convenient wrapper for kthread_create() followed by 9e37bd301ee130 Randy Dunlap 2006-06-25 48 * wake_up_process(). Returns the kthread or ERR_PTR(-ENOMEM). 9e37bd301ee130 Randy Dunlap 2006-06-25 49 */ ^1da177e4c3f41 Linus Torvalds 2005-04-16 50 #define kthread_run(threadfn, data, namefmt, ...) \ ^1da177e4c3f41 Linus Torvalds 2005-04-16 51 ({ \ ^1da177e4c3f41 Linus Torvalds 2005-04-16 52 struct task_struct *__k \ ^1da177e4c3f41 Linus Torvalds 2005-04-16 53 = kthread_create(threadfn, data, namefmt, ## __VA_ARGS__); \ ^1da177e4c3f41 Linus Torvalds 2005-04-16 54 if (!IS_ERR(__k)) \ ^1da177e4c3f41 Linus Torvalds 2005-04-16 @55 wake_up_process(__k); \ ^1da177e4c3f41 Linus Torvalds 2005-04-16 56 __k; \ ^1da177e4c3f41 Linus Torvalds 2005-04-16 57 }) ^1da177e4c3f41 Linus Torvalds 2005-04-16 58 :::::: The code at line 55 was first introduced by commit :::::: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Linux-2.6.12-rc2 :::::: TO: Linus Torvalds <torvalds(a)ppc970.osdl.org&gt; :::::: CC: Linus Torvalds <torvalds(a)ppc970.osdl.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org