linux-kernel - Re: [PATCH v3 1/1] selftests: vm: add process

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Date:   Wed, 18 May 2022 16:23:46 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Suren Baghdasaryan <surenb@...gle.com>, akpm@...ux-foundation.org
Cc:     mhocko@...e.com, rientjes@...gle.com, willy@...radead.org,
        hannes@...xchg.org, guro@...com, minchan@...nel.org,
        kirill@...temov.name, aarcange@...hat.com, brauner@...nel.org,
        hch@...radead.org, oleg@...hat.com, david@...hat.com,
        jannh@...gle.com, shakeelb@...gle.com, peterx@...hat.com,
        jhubbard@...dia.com, shuah@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-kselftest@...r.kernel.org, kernel-team@...roid.com,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH v3 1/1] selftests: vm: add process_mrelease tests

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@...gle.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@...uxfoundation.org>

thanks,
-- Shuah