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    SubjectRe: [PATCH v2 3/3] NFS: Fix a memory leak in nfs_readdir
    On Wed, Dec 1, 2010 at 3:36 PM, Andrew Morton <akpm@linux-foundation.org> wrote:
    > On Wed, 1 Dec 2010 15:31:11 -0800
    > Linus Torvalds <torvalds@linux-foundation.org> wrote:
    >>
    >> Ergo: vmscan has a locked page leads to the filesystem being
    >> guaranteed to not be unmounted.  And that, in turn, guarantees that
    >> the module won't be unloaded until the machine has gone through an
    >> idle cycle.
    >
    > The page isn't attached to the address_space any more:

    Did you even read the email?

    Here, let me quote the important parts:

    "module won't be unloaded until the machine has gone through an idle cycle"

    "This is pretty much how all the module races are handled. Doing module
    ref-counts per page (or per packet in flight for things like
    networking) would be prohibitively expensive."

    IOW, the whole "stop_machine()" part is fundamental. That whole
    "module unload won't happen until we've gone through an idle cycle" is
    EXACTLY why we don't need to have the page attached or ref-counted -
    we're still safe.

    Linus
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