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    SubjectRe: [PATCH 3/3] mlock: avoid dirtying pages and triggering writeback
    On Wed, Nov 17, 2010 at 04:23:58AM -0800, Michel Lespinasse wrote:
    > When faulting in pages for mlock(), we want to break COW for anonymous
    > or file pages within VM_WRITABLE, non-VM_SHARED vmas. However, there is
    > no need to write-fault into VM_SHARED vmas since shared file pages can
    > be mlocked first and dirtied later, when/if they actually get written to.
    > Skipping the write fault is desirable, as we don't want to unnecessarily
    > cause these pages to be dirtied and queued for writeback.

    It's not just to break COW, but to do block allocation and such
    (filesystem's page_mkwrite op). That needs to at least be explained
    in the changelog.

    Filesystem doesn't have a good way to fully pin required things
    according to mlock, but page_mkwrite provides some reasonable things
    (like block allocation / reservation).

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      Last update: 2010-11-17 14:01    [W:0.023 / U:4.828 seconds]
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