On Fri, 10 Apr 2026 12:32:43 +0800 Cao Ruichuang <[email protected]> wrote:
> Hi Masami, > > I reran this in clean QEMU on two kernels and got different results. > > 1. Ubuntu distro kernel: > Linux 6.8.0-100-generic #100-Ubuntu SMP PREEMPT_DYNAMIC > Tue Jan 13 16:40:06 UTC 2026 > > baseline count=2 > after_create123 count=4 > after_enable1/2/3 count=4 > > baseline enabled_functions: > __hid_bpf_tail_call ... > > after_create123 enabled_functions: > kernel_clone (2) R ->arch_ftrace_ops_list_func+0x0/0x280 > kmem_cache_free (1) R tramp: ... ->fprobe_handler+0x0/0x40 > __hid_bpf_tail_call ... > > 2. Current source-tree kernel built from the clean snapshot of my patch > branch: > Linux 7.0.0-rc6 #2 SMP PREEMPT_DYNAMIC Fri Apr 10 12:19:39 CST 2026 > > baseline count=0 > after_create123 count=0 > after_enable1 count=1 > after_enable2 count=1 > after_enable3 count=2 > > after_create123 enabled_functions: > <empty> > > after_enable3 enabled_functions: > kernel_clone (2) ->arch_ftrace_ops_list_func+0x0/0x200 > kmem_cache_free (1) tramp: ... ->fprobe_ftrace_entry+0x0/0x220 > > So the behavior I reported earlier reproduces on that Ubuntu 6.8 kernel, > but not on the current source-tree kernel. I think my earlier conclusion > was too broad. Thanks for reporting the difference of behaviors. > > I will stop pushing this testcase change for now unless I can narrow down > which kernel change caused the difference. OK. Thanks! > > Thanks, > Cao Ruichuang > -- Masami Hiramatsu (Google) <[email protected]>
