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    Subject[BUGFIX][PATCH] oom-kill: fix NUMA consraint check with nodemask v4.2
    On Tue, 10 Nov 2009 22:26:19 -0800 (PST)
    David Rientjes <rientjes@google.com> wrote:
    */
    > > > > + if (gfp_mask & __GPF_THISNODE)
    > > > > + return ret;
    > > > >
    > > >
    > > > That shouldn't compile.
    > > >
    > > Why ?
    > >
    >
    > Even when I pointed it out, you still didn't bother to try compiling it?
    > You need s/GPF/GFP, it stands for "get free pages."
    >
    You're right.
    Ah. I noticed CONFIG_NUMA=n
    ....(of course, I usually set it =y)

    > You can also eliminate the ret variable, it's not doing anything.
    >
    ok. fixed one here. Thank you.
    ==
    From: KAMEZAWA Hiroyuki <kamezawa.hioryu@jp.fujitsu.com>

    Fixing node-oriented allocation handling in oom-kill.c
    I myself think this as bugfix not as ehnancement.

    In these days, things are changed as
    - alloc_pages() eats nodemask as its arguments, __alloc_pages_nodemask().
    - mempolicy don't maintain its own private zonelists.
    (And cpuset doesn't use nodemask for __alloc_pages_nodemask())

    So, current oom-killer's check function is wrong.

    This patch does
    - check nodemask, if nodemask && nodemask doesn't cover all
    node_states[N_HIGH_MEMORY], this is CONSTRAINT_MEMORY_POLICY.
    - Scan all zonelist under nodemask, if it hits cpuset's wall
    this faiulre is from cpuset.
    And
    - modifies the caller of out_of_memory not to call oom if __GFP_THISNODE.
    This doesn't change "current" behavior. If callers use __GFP_THISNODE
    it should handle "page allocation failure" by itself.

    - handle __GFP_NOFAIL+__GFP_THISNODE path.
    This is something like a FIXME but this gfpmask is not used now.

    Changelog: 2009/11/11(2)
    - uses nodes_subset().
    - clean up.
    - added __GFP_NOFAIL case. And added waring.
    - removed inline
    - removed 'ret'

    Changelog: 2009/11/11
    - fixed nodes_equal() calculation.
    - return CONSTRAINT_MEMPOLICY always if given nodemask is not enough big.

    Changelog: 2009/11/06
    - fixed lack of oom.h

    Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hioryu@jp.fujitsu.com>
    ---
    drivers/char/sysrq.c | 2 +-
    include/linux/oom.h | 4 +++-
    mm/oom_kill.c | 46 +++++++++++++++++++++++++++++++++-------------
    mm/page_alloc.c | 20 +++++++++++++++-----
    4 files changed, 52 insertions(+), 20 deletions(-)

    Index: mm-test-kernel/drivers/char/sysrq.c
    ===================================================================
    --- mm-test-kernel.orig/drivers/char/sysrq.c
    +++ mm-test-kernel/drivers/char/sysrq.c
    @@ -339,7 +339,7 @@ static struct sysrq_key_op sysrq_term_op

    static void moom_callback(struct work_struct *ignored)
    {
    - out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0);
    + out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL);
    }

    static DECLARE_WORK(moom_work, moom_callback);
    Index: mm-test-kernel/mm/oom_kill.c
    ===================================================================
    --- mm-test-kernel.orig/mm/oom_kill.c
    +++ mm-test-kernel/mm/oom_kill.c
    @@ -196,27 +196,46 @@ unsigned long badness(struct task_struct
    /*
    * Determine the type of allocation constraint.
    */
    -static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
    - gfp_t gfp_mask)
    -{
    #ifdef CONFIG_NUMA
    +static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
    + gfp_t gfp_mask, nodemask_t *nodemask)
    +{
    struct zone *zone;
    struct zoneref *z;
    enum zone_type high_zoneidx = gfp_zone(gfp_mask);
    - nodemask_t nodes = node_states[N_HIGH_MEMORY];

    - for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
    - if (cpuset_zone_allowed_softwall(zone, gfp_mask))
    - node_clear(zone_to_nid(zone), nodes);
    - else
    - return CONSTRAINT_CPUSET;
    + /*
    + * Reach here only when __GFP_NOFAIL is used. So, we should avoid
    + * to kill current.We have to random task kill in this case.
    + * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now.
    + */
    + if (gfp_mask & __GFP_THISNODE)
    + return CONSTRAINT_NONE;

    - if (!nodes_empty(nodes))
    + /*
    + * The nodemask here is a nodemask passed to alloc_pages(). Now,
    + * cpuset doesn't use this nodemask for its hardwall/softwall/hierarchy
    + * feature. mempolicy is an only user of nodemask here.
    + * check mempolicy's nodemask contains all N_HIGH_MEMORY
    + */
    + if (nodemask && !nodes_subset(node_states[N_HIGH_MEMORY], *nodemask))
    return CONSTRAINT_MEMORY_POLICY;
    -#endif

    + /* Check this allocation failure is caused by cpuset's wall function */
    + for_each_zone_zonelist_nodemask(zone, z, zonelist,
    + high_zoneidx, nodemask)
    + if (!cpuset_zone_allowed_softwall(zone, gfp_mask))
    + return CONSTRAINT_CPUSET;
    +
    + return CONSTRAINT_NONE;
    +}
    +#else
    +static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
    + gfp_t gfp_mask, nodemask_t *nodemask)
    +{
    return CONSTRAINT_NONE;
    }
    +#endif

    /*
    * Simple selection loop. We chose the process with the highest
    @@ -603,7 +622,8 @@ rest_and_return:
    * OR try to be smart about which process to kill. Note that we
    * don't have to be perfect here, we just have to be good.
    */
    -void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
    +void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
    + int order, nodemask_t *nodemask)
    {
    unsigned long freed = 0;
    enum oom_constraint constraint;
    @@ -622,7 +642,7 @@ void out_of_memory(struct zonelist *zone
    * Check if there were limitations on the allocation (only relevant for
    * NUMA) that may require different handling.
    */
    - constraint = constrained_alloc(zonelist, gfp_mask);
    + constraint = constrained_alloc(zonelist, gfp_mask, nodemask);
    read_lock(&tasklist_lock);

    switch (constraint) {
    Index: mm-test-kernel/mm/page_alloc.c
    ===================================================================
    --- mm-test-kernel.orig/mm/page_alloc.c
    +++ mm-test-kernel/mm/page_alloc.c
    @@ -1664,12 +1664,22 @@ __alloc_pages_may_oom(gfp_t gfp_mask, un
    if (page)
    goto out;

    - /* The OOM killer will not help higher order allocs */
    - if (order > PAGE_ALLOC_COSTLY_ORDER && !(gfp_mask & __GFP_NOFAIL))
    - goto out;
    -
    + if (!(gfp_mask & __GFP_NOFAIL)) {
    + /* The OOM killer will not help higher order allocs */
    + if (order > PAGE_ALLOC_COSTLY_ORDER)
    + goto out;
    + /*
    + * GFP_THISNODE contains __GFP_NORETRY and we never hit this.
    + * Sanity check for bare calls of __GFP_THISNODE, not real OOM.
    + * The caller should handle page allocation failure by itself if
    + * it specifies __GFP_THISNODE.
    + * Note: Hugepage uses it but will hit PAGE_ALLOC_COSTLY_ORDER.
    + */
    + if (gfp_mask & __GFP_THISNODE)
    + goto out;
    + }
    /* Exhausted what can be done so it's blamo time */
    - out_of_memory(zonelist, gfp_mask, order);
    + out_of_memory(zonelist, gfp_mask, order, nodemask);

    out:
    clear_zonelist_oom(zonelist, gfp_mask);
    Index: mm-test-kernel/include/linux/oom.h
    ===================================================================
    --- mm-test-kernel.orig/include/linux/oom.h
    +++ mm-test-kernel/include/linux/oom.h
    @@ -10,6 +10,7 @@
    #ifdef __KERNEL__

    #include <linux/types.h>
    +#include <linux/nodemask.h>

    struct zonelist;
    struct notifier_block;
    @@ -26,7 +27,8 @@ enum oom_constraint {
    extern int try_set_zone_oom(struct zonelist *zonelist, gfp_t gfp_flags);
    extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);

    -extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order);
    +extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
    + int order, nodemask_t *mask);
    extern int register_oom_notifier(struct notifier_block *nb);
    extern int unregister_oom_notifier(struct notifier_block *nb);



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