在 2018年3月29日，下午7:26，Marian Marinov <kernel@xxxxxxxx> 写道： > > On 03/27/2018 06:20 PM, Chengguang Xu wrote: >>> Sent: Tuesday, March 27, 2018 at 9:58 PM >>> From: "Tejun Heo" <tj@xxxxxxxxxx> >>> To: "Chengguang Xu" <cgxu519@xxxxxxx> >>> Cc: lizefan@xxxxxxxxxx, cgroups@xxxxxxxxxxxxxxx >>> Subject: Re: [PATCH RFC] cpuset: change error code to -EPERM from -ENOSPC >>> >>> On Tue, Mar 27, 2018 at 06:02:24PM +0800, Chengguang Xu wrote: >>>> When adding task to cpuset with empty cpus_allowed or empty mems_allowed, >>>> there is an error with code -ENOSPC, it is a little bit confusing, >>>> so change error code to -EPERM for better understanding. >>>> >>>> Signed-off-by: Chengguang Xu <cgxu519@xxxxxxx> >>> >>> I don't see why we'd change this or how EPERM is necessarily more >>> intuitive here. >> >> After changing the error code, error message showed to user will change >> from >> >> $ echo $$ > /sys/fs/cgroup/cpuset/2/tasks >> -bash: echo: write error: No space left on device >> >> to >> >> $ echo $$ > /sys/fs/cgroup/cpuset/2/tasks >> -bash: echo: write error: Operation not permitted >> >> Isn't it more understandable? IIUC, the logic here is for prohibiting attaching or >> changing operations. > > I somewhat agree that "Operation not permitted" is a bit more meaningful. > However this is something that has been in the kernel for a lot of years and changing it to another error message, that is also not the actual cause is not solving anyone's problems with this ;( Actually, the motivation of this patch is from my experience. I encountered -ENOSPC when I try to manipulate cpuset, then I had no idea about the reason at all, so I had to dive into the code to analyze the root cause, but I think there are also many sysadmins do not understand the code, so meaningful error message is much helpful to them. IMHO, it’s a trivial change and it will not bring side effect so the change would not be so difficult though the -ENOSPC has been in kernel for a long time. > > The other thing is, that "Operation not permitted" may push the sysadmins in completely different search, like is it a SELinux related problem. I also propose to add additional warning message here to give some hints to sysadmins, but I guess mismatched warning/error messages will also cause users’ confusing. Thanks, Chengguang. -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
