Re: [PATCH v11 4/6] mm: function to offer a page block on the free list

From	Dave Hansen <dave.hansen@intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v11 4/6] mm: function to offer a page block on the free list
Date	2017-06-12 16:20 +0200
Message-ID	<tRyme-3aL-9@gated-at.bofh.it> (permalink)
References	<tQpEl-qv-1@gated-at.bofh.it> <tQpEl-qv-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Please stop cc'ing me on things also sent to closed mailing lists
(virtio-dev@lists.oasis-open.org).  I'm happy to review things on open
lists, but I'm not fond of the closed lists bouncing things at me.

On 06/09/2017 03:41 AM, Wei Wang wrote:
> Add a function to find a page block on the free list specified by the
> caller. Pages from the page block may be used immediately after the
> function returns. The caller is responsible for detecting or preventing
> the use of such pages.

This description doesn't tell me very much about what's going on here.
Neither does the comment.

"Pages from the page block may be used immediately after the
 function returns".

Used by who?  Does the "may" here mean that it is OK, or is it a warning
that the contents will be thrown away immediately?

The hypervisor is going to throw away the contents of these pages,
right?  As soon as the spinlock is released, someone can allocate a
page, and put good data in it.  What keeps the hypervisor from throwing
away good data?

Thread

[PATCH v11 0/6] Virtio-balloon Enhancement Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
  [PATCH v11 5/6] mm: export symbol of next_zone and first_online_pgdat Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
  [PATCH v11 4/6] mm: function to offer a page block on the free list Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
    Re: [PATCH v11 4/6] mm: function to offer a page block on the free  list Dave Hansen <dave.hansen@intel.com> - 2017-06-12 16:20 +0200
      Re: [PATCH v11 4/6] mm: function to offer a page block on the free  list "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-12 18:30 +0200
        Re: [PATCH v11 4/6] mm: function to offer a page block on the free  list Dave Hansen <dave.hansen@intel.com> - 2017-06-12 18:50 +0200
          Re: [PATCH v11 4/6] mm: function to offer a page block on the free  list "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-12 22:40 +0200
            Re: [PATCH v11 4/6] mm: function to offer a page block on the free  list Dave Hansen <dave.hansen@intel.com> - 2017-06-12 23:00 +0200
              Re: [PATCH v11 4/6] mm: function to offer a page block on the free  list Wei Wang <wei.w.wang@intel.com> - 2017-06-13 05:00 +0200
  [PATCH v11 1/6] virtio-balloon: deflate via a page list Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
  [PATCH v11 2/6] virtio-balloon: coding format cleanup Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
  [PATCH v11 6/6] virtio-balloon: VIRTIO_BALLOON_F_CMD_VQ Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
    Re: [PATCH v11 6/6] virtio-balloon: VIRTIO_BALLOON_F_CMD_VQ Dave Hansen <dave.hansen@intel.com> - 2017-06-12 16:10 +0200
      Re: [PATCH v11 6/6] virtio-balloon: VIRTIO_BALLOON_F_CMD_VQ Wei Wang <wei.w.wang@intel.com> - 2017-06-13 12:20 +0200
  [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS Wei Wang <wei.w.wang@intel.com> - 2017-06-09 13:00 +0200
    Re: [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-13 20:00 +0200
      Re: [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS Dave Hansen <dave.hansen@intel.com> - 2017-06-13 20:00 +0200
        Re: [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-13 21:00 +0200
      Re: [virtio-dev] Re: [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS Wei Wang <wei.w.wang@intel.com> - 2017-06-15 10:10 +0200
        Re: [virtio-dev] Re: [PATCH v11 3/6] virtio-balloon:  VIRTIO_BALLOON_F_PAGE_CHUNKS "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-16 05:20 +0200
  RE: [PATCH v11 0/6] Virtio-balloon Enhancement "Wang, Wei W" <wei.w.wang@intel.com> - 2017-06-09 13:20 +0200

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