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Steve Sistare 26a8ea8092 mm/hugetlb: fix memfd_pin_folios resv_huge_pages leak
memfd_pin_folios followed by unpin_folios leaves resv_huge_pages elevated
if the pages were not already faulted in.  During a normal page fault,
resv_huge_pages is consumed here:

hugetlb_fault()
  alloc_hugetlb_folio()
    dequeue_hugetlb_folio_vma()
      dequeue_hugetlb_folio_nodemask()
        dequeue_hugetlb_folio_node_exact()
          free_huge_pages--
      resv_huge_pages--

During memfd_pin_folios, the page is created by calling
alloc_hugetlb_folio_nodemask instead of alloc_hugetlb_folio, and
resv_huge_pages is not modified:

memfd_alloc_folio()
  alloc_hugetlb_folio_nodemask()
    dequeue_hugetlb_folio_nodemask()
      dequeue_hugetlb_folio_node_exact()
        free_huge_pages--

alloc_hugetlb_folio_nodemask has other callers that must not modify
resv_huge_pages.  Therefore, to fix, define an alternate version of
alloc_hugetlb_folio_nodemask for this call site that adjusts
resv_huge_pages.

Link: https://lkml.kernel.org/r/1725373521-451395-4-git-send-email-steven.sistare@oracle.com
Fixes: 89c1905d9c ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios")
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Acked-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-26 14:01:43 -07:00
arch i2c-for-6.12-rc1 2024-09-23 14:34:19 -07:00
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Documentation media updates for v6.12-rc1 2024-09-23 15:27:58 -07:00
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fs NFSD 6.12 Release Notes 2024-09-23 12:01:45 -07:00
include mm/hugetlb: fix memfd_pin_folios resv_huge_pages leak 2024-09-26 14:01:43 -07:00
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kernel pci-v6.12-changes 2024-09-23 12:47:06 -07:00
lib The core clk framework is left largely untouched this time around except for 2024-09-23 15:01:48 -07:00
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mm mm/hugetlb: fix memfd_pin_folios resv_huge_pages leak 2024-09-26 14:01:43 -07:00
net NFSD 6.12 Release Notes 2024-09-23 12:01:45 -07:00
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tools tools: fix shared radix-tree build 2024-09-26 14:01:43 -07:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.