From: Rik van Riel <riel@surriel.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com,
linux-mm@kvack.org, akpm@linux-foundation.org,
muchun.song@linux.dev, leit@meta.com, willy@infradead.org
Subject: Re: [PATCH 2/3] hugetlbfs: close race between MADV_DONTNEED and page fault
Date: Tue, 03 Oct 2023 20:20:02 -0400 [thread overview]
Message-ID: <c5c77b6cadde9032ad1941bd7610cfb3925ac1ab.camel@surriel.com> (raw)
In-Reply-To: <20231003201916.GD314430@monkey>
On Tue, 2023-10-03 at 13:19 -0700, Mike Kravetz wrote:
> On 10/03/23 15:35, Rik van Riel wrote:
> > On Sun, 2023-10-01 at 21:39 -0700, Mike Kravetz wrote:
> > >
> > > Something is not right here. I have not looked closely at the
> > > patch,
> > > but running libhugetlbfs test suite hits this NULL deref in
> > > misalign
> > > (2M: 32).
> >
> > Hi Mike,
> >
> > fixing the null dereference was easy, but I continued running
> > into a test case failure with linkhuge_rw. After tweaking the
> > code in my patches quite a few times, I finally ran out of
> > ideas and tried it on a tree without my patches.
> >
> > I still see the test failure on upstream
> > 2cf0f7156238 ("Merge tag 'nfs-for-6.6-2' of git://git.linux-
> > nfs.org/projects/anna/linux-nfs")
> >
> > This is with a modern glibc, and the __morecore assignments
> > in libhugetlbfs/morecore.c commented out.
> >
> >
> > HUGETLB_ELFMAP=R HUGETLB_SHARE=1 linkhuge_rw (2M: 32): Pool state:
> > (('hugepages-2048kB', (('free_hugepages', 1), ('resv_hugepages',
> > 0),
> > ('surplus_hugepages', 0), ('nr_hugepages_mempolicy', 1),
> > ('nr_hugepages', 1), ('nr_overcommit_hugepages', 0))),)
> > Hugepage pool state not preserved!
> > BEFORE: (('hugepages-2048kB', (('free_hugepages', 1),
> > ('resv_hugepages', 0), ('surplus_hugepages', 0),
> > ('nr_hugepages_mempolicy', 1), ('nr_hugepages', 1),
> > ('nr_overcommit_hugepages', 0))),)
> > AFTER: (('hugepages-2048kB', (('free_hugepages', 0),
> > ('resv_hugepages',
> > 0), ('surplus_hugepages', 0), ('nr_hugepages_mempolicy', 1),
> > ('nr_hugepages', 1), ('nr_overcommit_hugepages', 0))),)
> >
>
> Please consider the above failures normal and expected. That have
> been
> this way for many years. Sorry for any waste of your time.
>
> Of course, if you would like to look into these you are welcome.
I'm not too worried about the test cases returning failure,
but having free_hugepages not go back to 1 after linkhuge_rw
exits looks bad.
In this case it appears that linkhuge_rw simply left behind
a file in /dev/hugepages when it died, and removing that file
returns free_hugepages back to what it should be.
I guess I'll go run the test cases without -c 1 :)
--
All Rights Reversed.
next prev parent reply other threads:[~2023-10-04 0:20 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-01 0:55 [PATCH v5 0/3] " riel
2023-10-01 0:55 ` [PATCH 1/3] hugetlbfs: extend hugetlb_vma_lock to private VMAs riel
2023-10-01 0:55 ` [PATCH 2/3] hugetlbfs: close race between MADV_DONTNEED and page fault riel
2023-10-02 4:39 ` Mike Kravetz
2023-10-02 13:13 ` Rik van Riel
2023-10-03 19:35 ` Rik van Riel
2023-10-03 20:19 ` Mike Kravetz
2023-10-04 0:20 ` Rik van Riel [this message]
2023-10-01 0:55 ` [PATCH 3/3] hugetlbfs: replace hugetlb_vma_lock with invalidate_lock riel
2023-10-02 5:22 ` Mike Kravetz
2023-10-01 2:54 ` [PATCH v5 0/3] hugetlbfs: close race between MADV_DONTNEED and page fault Andrew Morton
-- strict thread matches above, loose matches on Subject: below --
2023-10-04 3:25 [PATCH v6 " riel
2023-10-04 3:25 ` [PATCH 2/3] " riel
2023-10-05 3:19 ` Mike Kravetz
2023-10-05 13:23 ` Rik van Riel
2023-10-05 22:59 ` Mike Kravetz
2023-09-26 3:10 [PATCH v4 0/3] " riel
2023-09-26 3:10 ` [PATCH 2/3] " riel
2023-09-26 21:15 ` Andrew Morton
2023-09-26 23:57 ` Rik van Riel
2023-09-25 20:28 [PATCH v3 0/3] " riel
2023-09-25 20:28 ` [PATCH 2/3] " riel
2023-09-25 22:25 ` Mike Kravetz
2023-09-26 0:46 ` Rik van Riel
2023-09-22 19:02 [PATCH v2 0/3] " riel
2023-09-22 19:02 ` [PATCH 2/3] " riel
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