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    SubjectRe: must-fix list for 2.6.0
    On Tue, Apr 29, 2003 at 03:57:31PM -0700, Andrew Morton wrote:
    > mm/
    > ---
    > - Overcommit accounting gets wrong answers
    > - underestimates reclaimable slab, gives bogus failures when
    > dcache&icache are large.
    > - gets confused by reclaimable-but-not-freed truncated ext3 pages.
    > Lame fix exists in -mm.
    > - Proper user level no overcommit also requires a root margin adding

    I didn't notice anything specific here about sys_remap_file_pages() vs.
    truncate() (sans objrmap); did a fix fly by that I didn't notice,
    or was it less of an issue than I thought it was?

    Also, the OOM killer fails to check lowmem; basically it just needs
    - if (nr_swap_pages > 0)
    + if (nr_swap_pages > 0 && nr_free_buffer_pages() > 0)

    With that in addition to the OOM killer locking patch I posted and
    another to completely eliminate mm-less processes from consideration
    64GB ia32 (with, of course, my oversized out-of-tree patch) recovers
    from OOM instead of deadlocking after a mass-killing with swap online.
    Not that I'd consider 64GB ia32 a supported platform for 2.5/2.6 (it's
    a design limitation IMHO); it merely "stresses the OOM killer harder"
    for the purposes of this discussion. Some kind of investigation is
    probably needed to determine why eliminating mm-less processes from
    consideration is necessary to obtain the desired behavior.

    I'd be interested in more detailed descriptions of the user-level no
    overcommit, dcacheicache, and truncated ext3 page issues after Thursday.


    On Tue, Apr 29, 2003 at 03:57:31PM -0700, Andrew Morton wrote:
    > mm/
    > ---
    > - objrmap: concerns over page reclaim performance at high sharing levels,
    > and interoperation with nonlinear mappings is hairy.
    > - Readd and make /proc/sys/vm/freepages writable again so that boxes can be
    > tuned for heavy interrupt load.

    The latter sounds easy to address. It actually sounds like a 2.4.x
    compatibility fix.


    -- wli
    -
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