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    Subject[PATCH 05/14] mm: Ignore mempolicies when using ALLOC_NO_WATERMARK
    Date
    The reserve is proportionally distributed over all !highmem zones in the
    system. So we need to allow an emergency allocation access to all zones.
    In order to do that we need to break out of any mempolicy boundaries we
    might have.

    In my opinion that does not break mempolicies as those are user oriented
    and not system oriented. That is, system allocations are not guaranteed to
    be within mempolicy boundaries. For instance IRQs don't even have a mempolicy.

    So breaking out of mempolicy boundaries for 'rare' emergency allocations,
    which are always system allocations (as opposed to user) is ok.

    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Signed-off-by: Mel Gorman <mgorman@suse.de>
    ---
    mm/page_alloc.c | 7 +++++++
    1 files changed, 7 insertions(+), 0 deletions(-)
    diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    index 4e19606..ac779f5 100644
    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -2126,6 +2126,13 @@ rebalance:

    /* Allocate without watermarks if the context allows */
    if (alloc_flags & ALLOC_NO_WATERMARKS) {
    + /*
    + * Ignore mempolicies if ALLOC_NO_WATERMARKS on the grounds
    + * the allocation is high priority and these type of
    + * allocations are system rather than user orientated
    + */
    + zonelist = node_zonelist(numa_node_id(), gfp_mask);
    +
    page = __alloc_pages_high_priority(gfp_mask, order,
    zonelist, high_zoneidx, nodemask,
    preferred_zone, migratetype);
    --
    1.7.3.4


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