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From:   Mina Almasry <almasrymina@google.com>
Date:   Tue, 4 Feb 2020 14:33:29 -0800
Message-ID: <CAHS8izNmSYumXpYXT1d8tAm36=-BRjXqdCDjLB6UNMwn5xhPZg@mail.gmail.com>
Subject: Re: [PATCH v11 8/9] hugetlb_cgroup: Add hugetlb_cgroup reservation tests
To:     Sandipan Das <sandipan@linux.ibm.com>
Cc:     Mike Kravetz <mike.kravetz@oracle.com>, shuah <shuah@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Shakeel Butt <shakeelb@google.com>,
        Greg Thelen <gthelen@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        open list <linux-kernel@vger.kernel.org>, linux-mm@kvack.org,
        linux-kselftest@vger.kernel.org, cgroups@vger.kernel.org
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On Tue, Feb 4, 2020 at 12:36 PM Mina Almasry <almasrymina@google.com> wrote:
>
> On Tue, Feb 4, 2020 at 8:26 AM Sandipan Das <sandipan@linux.ibm.com> wrote:
> >
> >
> > There are still a couple of places where 2MB page size is being used.
> > These are my workarounds to get the tests running on ppc64.
> >
>
> Thanks for the changes!
>
> > Also I had missed running charge_reserved_hugetlb.sh the last time.
> > Right now, it stops at the following scenario.
> >
> > Test normal case with write.
> > private=, populate=, method=2, reserve=
> > nr hugepages = 10
> > writing cgroup limit: 83886080
> > writing reseravation limit: 83886080
> >
> > Starting:
> > hugetlb_usage=0
> > reserved_usage=0
> > expect_failure is 0
> > Putting task in cgroup 'hugetlb_cgroup_test'
> > Method is 2
> > Executing ./write_to_hugetlbfs -p /mnt/huge/test -s 83886080 -w  -m 2  -l
> > Writing to this path: /mnt/huge/test
> > Writing this size: 83886080
> > Not populating.
> > Using method=2
> > Shared mapping.
> > RESERVE mapping.
> > Allocating using SHM.
> > shmid: 0x5, shmget key:0
> > shmaddr: 0x7dfffb000000
> > Writing to memory.
> > Starting the writes:
> > .write_result is 0
> > .After write:
> > hugetlb_usage=16777216
> > reserved_usage=83886080
> > ....kiling write_to_hugetlbfs
> > ...Received 2.
> > Deleting the memory
> > Done deleting the memory
> > 16777216
> > 83886080
> > Memory charged to hugtlb=16777216
> > Memory charged to reservation=83886080
> > expected (83886080) != actual (16777216): Reserved memory charged to hugetlb cgroup.
> > CLEANUP DONE
> >
> >
>
> So the problem in this log seems to be that this log line is missing:
>     echo Waiting for hugetlb memory to reach size $size.
>
> The way the test works is that it starts a process that writes the
> hugetlb memory, then it *should* wait until the memory is written,
> then it should record the cgroup accounting and kill the process. It
> seems from your log that the wait doesn't happen, so the test
> continues before the background process has had time to write the
> memory properly. Essentially wait_for_hugetlb_memory_to_get_written()
> never gets called in your log.
>
> Can you try this additional attached diff on top of your changes? I
> attached the diff and pasted the same here, hopefully one works for
> you:
>

I got my hands on a machine with 16MB default hugepage size and
charge_reserved_hugetlb.sh passes now after my changes. Please let me
know if you still run into issues.