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 15:35:25 -0400 [thread overview]
Message-ID: <8d19b6d092b7b5d9b1d0829e0d99c9915db3ed61.camel@surriel.com> (raw)
In-Reply-To: <20231002043958.GB11194@monkey>
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))),)
It may take a little while to figure this one out. I did some
bpftracing, but don't have a real smoking gun yet. The trace
certainly shows the last user of the leaked huge page going
into __unmap_hugepage_range.
--
All Rights Reversed.
next prev parent reply other threads:[~2023-10-03 19:35 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-01 0:55 [PATCH v5 0/3] hugetlbfs: close race between MADV_DONTNEED and page fault 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 [this message]
2023-10-03 20:19 ` Mike Kravetz
2023-10-04 0:20 ` Rik van Riel
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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