Hi, Eric, On Tue, Sep 12, 2023 at 9:59 AM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > Huacai Chen <chenhuacai@xxxxxxxxxx> writes: > > > Hi, all, > > > > Friendly ping again? > > > > > > Huacai > > > > On Sun, Jul 23, 2023 at 10:13 PM Huacai Chen <chenhuacai@xxxxxxxxxx> wrote: > >> > >> Hi, Eric, > >> > >> On Tue, Jul 18, 2023 at 8:43 PM Huacai Chen <chenhuacai@xxxxxxxxxx> wrote: > >> > > >> > Hi, Luis, > >> > > >> > On Sat, Jul 1, 2023 at 7:25 AM Luis Chamberlain <mcgrof@xxxxxxxxxx> wrote: > >> > > > >> > > On Sun, Jun 25, 2023 at 04:55:33PM +0800, Huacai Chen wrote: > >> > > > Friendly ping? > >> > > > >> > > You want to cc the folks who Nacked your patch. Until then, this > >> > > probably can't go further. > >> > Thank you very much. Eric and Andrew are already in the CC list, so > >> > add Thomas now. > >> > > >> > My brain is a little old-fashioned so I insisted that "a thread > >> > without mm_struct should be a kernel thread" in the previous patch. > >> > Unfortunately this makes Eric and Thomas unhappy, I'm very sorry for > >> > that. > >> > > >> > During the discussion of the previous patch I know I made some > >> > mistakes about some basic concepts, but I also found the name > >> > "user_mode_thread()" is somewhat confusing. I think rename it to > >> > kmuser_thread() is better, because: > >> > 1, it identify init and umh as user threads; > >> > 2, it points out that init and umh are special user threads that run > >> > in kernel mode before loading a user program. > >> > > >> > Sorry for my rudeness again. > >> Excuse me, but could you please tell me what your opinion is. In my > >> opinion a typical user thread is created by > >> pthread_create()/sys_clone(), it is better to distinguish typical user > >> threads from init and umh. > > If we want to emphasize that it is a kernel concept I am happy with > renaming user_mode_thread to user_mode_task. That is more accurate. > > But all threads from the kernel perspective are tasks. Further > all threads have times when they run code in the kernel (aka system > calls) and times when they run code in userspace. > > Linux kernel tasks created with user_mode_thread() are exactly like > other user mode tasks, and have all treated exactly the same was by the > system as any the tasks created by pthread_create() and sys_clone(). > > The only oddity is that there is no user mode code to execute until > after execve is called. > > When running code in the kernel, user space threads never logically > do not use the user space page tables. > > They are different in some significant ways from tasks created with > kernel_thread(). Tasks created with kernel_thread do not support > calling execve, among other things. > > But deeply and fundamentally I think you are trying to make a > distinction that is not there. All user space threads run code > in the kernel before they run code in userspace. Most often > it is from the system calls fork/clone/exec. For init and umh it > is effectively a special dedicated system call that includes > an execve. > > Let me ask what difference are you trying to high light that callers > of user_mode_thread need to be aware of? What problem in thinking > do you think that the name user_mode_thread creates? I am asking > because I might just be missing your point. 1, My first key point is “intuition”, by intuition sys_clone()/pthread_create() creates a user thread, but init and umh are more or less different (special user thread). 2, My second key point is "symmetry", for symmetry ‘kernel_thread’ is a counterpart of ‘user_thread’, while ‘user_mode_thread’ is a counterpart of ‘kernel_mode_thread’. If we keep the ‘kernel_thread’ name, then we can only rename the ‘user_mode_thread’. As discussed before, init and umh are user threads, but they are special user threads run in kernel mode before kernel_execve, so I want to rename it to ‘user_thread’ with a 'km' prefix, so ‘kmuser_thread’. Huacai > > Eric
