Re: [PATCH] selftests/mm: Add CONFIG_FTRACE to config

[Pedro Falcato <pfalcato@suse.de>]

On Thu, Jun 12, 2025 at 11:58:21AM +0530, Dev Jain wrote:
> 
> On 11/06/25 6:00 pm, Pedro Falcato wrote:
> > On Wed, Jun 11, 2025 at 05:40:11PM +0530, Dev Jain wrote:
> > > If CONFIG_UPROBES is not set, a merge subtest fails:
> > > 
> > > Failure log:
> > > 
> > >    7151 12:46:54.627936  # # #  RUN           merge.handle_uprobe_upon_merged_vma ...
> > >    7152 12:46:54.639014  # # f /sys/bus/event_source/devices/uprobe/type
> > >    7153 12:46:54.639306  # # fopen: No such file or directory
> > >    7154 12:46:54.650451  # # # merge.c:473:handle_uprobe_upon_merged_vma:Expected read_sysfs("/sys/bus/event_source/devices/uprobe/type", &type) (1) == 0 (0)
> > >    7155 12:46:54.650730  # # # handle_uprobe_upon_merged_vma: Test terminated by assertion
> > >    7156 12:46:54.661750  # # #          FAIL  merge.handle_uprobe_upon_merged_vma
> > >    7157 12:46:54.662030  # # not ok 8 merge.handle_uprobe_upon_merged_vma
> > > 
> > > CONFIG_UPROBES is enabled by CONFIG_UPROBE_EVENTS, which gets enabled by
> > > CONFIG_FTRACE. Therefore add this config to selftests/mm/config so that
> > > CI systems can include this config in the kernel build.
> > While I did consider this before sending my patch, not every architecture
> > supports uprobes :/ So this isn't a complete fix.
> > 
> > Also, does every architecture support ftrace? If not (and it does not seem so,
> > e.g there's an ARM variant that does not), I would guess this config fragment
> > blows up.
> 
> Sorry forgot to reply.
> 
> What do you mean by "config fragment blows up"? I think scripts will just pull
> these configs and build the kernel, and if the config is not supported, it will
> be thrown out of .config, and after applying your patch, the test will be skipped,
> so everyone is happy I guess?

Right, I spoke with Mark Brown off-list and apparently it should be safe to add
unsupported config options there (and I wasn't sure about that, maybe it could
fail, or maybe kbuild would fail, or<...>). So yeah, I'm fully supportive of
a patch adding CONFIG_UPROBES.

- 
Pedro