Re: [PATCH v3 1/1] selftests: vm: add process_mrelease tests

[Shuah Khan <skhan@linuxfoundation.org>]

On 5/18/22 2:43 PM, Suren Baghdasaryan wrote:
> Introduce process_mrelease syscall sanity tests which include tests
> which expect to fail:
> - process_mrelease with invalid pidfd and flags inputs
> - process_mrelease on a live process with no pending signals
> and valid process_mrelease usage which is expected to succeed.
> Because process_mrelease has to be used against a process with a pending
> SIGKILL, it's possible that the process exits before process_mrelease
> gets called. In such cases we retry the test with a victim that allocates
> twice more memory up to 1GB. This would require the victim process to
> spend more time during exit and process_mrelease has a better chance of
> catching the process before it exits and succeeding.
> 
> On success the test reports the amount of memory the child had to
> allocate for reaping to succeed. Sample output:
> 
> $ mrelease_test
> Success reaping a child with 1MB of memory allocations
> 
> On failure the test reports the failure. Sample outputs:
> 
> $ mrelease_test
> All process_mrelease attempts failed!
> 
> $ mrelease_test
> process_mrelease: Invalid argument
> 
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
> Changes in v3:
> - Applied on git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm mm-stable,
> per Andrew
> - Fixed formatting for sample outputs in the description, per Shuah
> - Removed pidfd_open, process_mrelease, write_fault_pages functions, per Shuah
> - Moved child main routine into its own function, per Shuah
> - Followed tools/testing/selftests/pidfd/pidfd.h as a model to deal with
> undefined syscall numbers, per Shuah
> 

Looks good to me Suren. Thank you.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah