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charset=utf-8 Content-Transfer-Encoding: quoted-printable tree: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git sche= d/preempt-dynamic-optimizations head: b07713067f078a16fdbf289db10c6f72a7a75aa0 commit: b07713067f078a16fdbf289db10c6f72a7a75aa0 [1/1] HACK: sched: Disable= {cond,might}_resched() when ARCH_HAS_PREEMPT_LAZY=3Dy config: s390-randconfig-001-20260226 (https://download.01.org/0day-ci/archi= ve/20260226/202602260409.2GS5AzSo-lkp@intel.com/config) compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project 9a1= 09fbb6e184ec9bcce10615949f598f4c974a9) reproduce (this is a W=3D1 build): (https://download.01.org/0day-ci/archive= /20260226/202602260409.2GS5AzSo-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new versio= n of the same patch/commit), kindly add following tags | Reported-by: kernel test robot | Closes: https://lore.kernel.org/oe-kbuild-all/202602260409.2GS5AzSo-lkp@i= ntel.com/ All warnings (new ones prefixed by >>): >> kernel/sched/core.c:7415:13: warning: no previous prototype for function= '__cond_resched' [-Wmissing-prototypes] 7415 | int __sched __cond_resched(void) | ^ kernel/sched/core.c:7415:1: note: declare 'static' if the function is no= t intended to be used outside of this translation unit 7415 | int __sched __cond_resched(void) | ^ | static=20 kernel/sched/core.c:7455:13: warning: no previous prototype for function= 'dynamic_cond_resched' [-Wmissing-prototypes] 7455 | int __sched dynamic_cond_resched(void) | ^ kernel/sched/core.c:7455:1: note: declare 'static' if the function is no= t intended to be used outside of this translation unit 7455 | int __sched dynamic_cond_resched(void) | ^ | static=20 >> kernel/sched/core.c:7464:13: warning: no previous prototype for function= 'dynamic_might_resched' [-Wmissing-prototypes] 7464 | int __sched dynamic_might_resched(void) | ^ kernel/sched/core.c:7464:1: note: declare 'static' if the function is no= t intended to be used outside of this translation unit 7464 | int __sched dynamic_might_resched(void) | ^ | static=20 3 warnings generated. vim +/__cond_resched +7415 kernel/sched/core.c d50dde5a10f305 kernel/sched/core.c Dario Faggioli 2013-11-07 7413 =20 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7414 #if= !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 @7415 int= __sched __cond_resched(void) ^1da177e4c3f41 kernel/sched.c Linus Torvalds 2005-04-16 7416 { 82c387ef7568c0 kernel/sched/core.c Thomas Gleixner 2024-12-16 7417 if= (should_resched(0) && !irqs_disabled()) { 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7418 p= reempt_schedule_common(); 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7419 r= eturn 1; ^1da177e4c3f41 kernel/sched.c Linus Torvalds 2005-04-16 7420 } ^1da177e4c3f41 kernel/sched.c Linus Torvalds 2005-04-16 7421 /* 2c00e1199c0608 kernel/sched/core.c Ankur Arora 2024-12-12 7422 *= In PREEMPT_RCU kernels, ->rcu_read_lock_nesting tells the tick 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7423 *= whether the current CPU is in an RCU read-side critical section, 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7424 *= so the tick can report quiescent states even for CPUs looping 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7425 *= in kernel context. In contrast, in non-preemptible kernels, 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7426 *= RCU readers leave no in-memory hints, which means that CPU-bound 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7427 *= processes executing in kernel context might never report an 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7428 *= RCU quiescent state. Therefore, the following code causes 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7429 *= cond_resched() to report a quiescent state, but only when RCU 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7430 *= is in urgent need of one. 2c00e1199c0608 kernel/sched/core.c Ankur Arora 2024-12-12 7431 *= A third case, preemptible, but non-PREEMPT_RCU provides for 2c00e1199c0608 kernel/sched/core.c Ankur Arora 2024-12-12 7432 *= urgently needed quiescent states via rcu_flavor_sched_clock_irq(). ^1da177e4c3f41 kernel/sched.c Linus Torvalds 2005-04-16 7433 */ 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7434 #if= ndef CONFIG_PREEMPT_RCU 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7435 rc= u_all_qs(); 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7436 #en= dif 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7437 re= turn 0; ^1da177e4c3f41 kernel/sched.c Linus Torvalds 2005-04-16 7438 } 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7439 EXP= ORT_SYMBOL(__cond_resched); 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7440 #en= dif ^1da177e4c3f41 kernel/sched.c Linus Torvalds 2005-04-16 7441 =20 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7442 #if= def CONFIG_PREEMPT_DYNAMIC b7ebb758568b60 kernel/sched/core.c Ingo Molnar 2025-05-28 7443 # i= fdef CONFIG_HAVE_PREEMPT_DYNAMIC_CALL 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7444 # = define cond_resched_dynamic_enabled __cond_resched 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7445 # = define cond_resched_dynamic_disabled ((void *)&__static_call_return0) 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7446 DEF= INE_STATIC_CALL_RET0(cond_resched, __cond_resched); 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7447 EXP= ORT_STATIC_CALL_TRAMP(cond_resched); 48f24c4da1ee7f kernel/sched.c Ingo Molnar 2006-07-03 7448 =20 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7449 # = define might_resched_dynamic_enabled __cond_resched 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7450 # = define might_resched_dynamic_disabled ((void *)&__static_call_return0) 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7451 DEF= INE_STATIC_CALL_RET0(might_resched, __cond_resched); 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7452 EXP= ORT_STATIC_CALL_TRAMP(might_resched); 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7453 # e= lif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7454 sta= tic DEFINE_STATIC_KEY_FALSE(sk_dynamic_cond_resched); 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7455 int= __sched dynamic_cond_resched(void) 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7456 { 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7457 if= (!static_branch_unlikely(&sk_dynamic_cond_resched)) 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7458 r= eturn 0; 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7459 re= turn __cond_resched(); 700a78335fc28a kernel/sched/core.c Christian G=C3=B6ttsche 2022-06-15 7460= } 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7461 EXP= ORT_SYMBOL(dynamic_cond_resched); 700a78335fc28a kernel/sched/core.c Christian G=C3=B6ttsche 2022-06-15 7462= =20 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7463 sta= tic DEFINE_STATIC_KEY_FALSE(sk_dynamic_might_resched); 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 @7464 int= __sched dynamic_might_resched(void) 700a78335fc28a kernel/sched/core.c Christian G=C3=B6ttsche 2022-06-15 7465= { 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7466 if= (!static_branch_unlikely(&sk_dynamic_might_resched)) 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7467 r= eturn 0; 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7468 re= turn __cond_resched(); e43379f10b4219 kernel/sched.c Matt Mackall 2005-05-01 7469 } 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7470 EXP= ORT_SYMBOL(dynamic_might_resched); 04746ed80bcf31 kernel/sched/core.c Ingo Molnar 2024-04-07 7471 # e= ndif b7ebb758568b60 kernel/sched/core.c Ingo Molnar 2025-05-28 7472 #en= dif /* CONFIG_PREEMPT_DYNAMIC */ ^1da177e4c3f41 kernel/sched.c Linus Torvalds 2005-04-16 7473 =20 :::::: The code at line 7415 was first introduced by commit :::::: 04746ed80bcf3130951ed4d5c1bc5b0bcabdde22 sched/syscalls: Split out k= ernel/sched/syscalls.c from kernel/sched/core.c :::::: TO: Ingo Molnar :::::: CC: Ingo Molnar --=20 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki