Re: [BUGFIX][PATCH] oom-kill: fix NUMA consraint check with nodemaskv3
From: David Rientjes
Date: Tue Nov 10 2009 - 21:50:05 EST
On Wed, 11 Nov 2009, KAMEZAWA Hiroyuki wrote:
> 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 +196,45 @@ unsigned long badness(struct task_struct
> /*
> * Determine the type of allocation constraint.
> */
> +#ifdef CONFIG_NUMA
> static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
> - gfp_t gfp_mask)
> + gfp_t gfp_mask, nodemask_t *nodemask)
We should probably remove the inline specifier, there's only one caller
currently and if additional ones were added in the future this function
should probably not be replicated.
> {
> -#ifdef CONFIG_NUMA
> struct zone *zone;
> struct zoneref *z;
> enum zone_type high_zoneidx = gfp_zone(gfp_mask);
> - nodemask_t nodes = node_states[N_HIGH_MEMORY];
> + int ret = CONSTRAINT_NONE;
>
> - 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
> + /*
> + * 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.
> + */
> + if (nodemask) {
> + nodemask_t mask;
> + /* check mempolicy's nodemask contains all N_HIGH_MEMORY */
> + nodes_and(mask, *nodemask, node_states[N_HIGH_MEMORY]);
> + if (!nodes_equal(mask, node_states[N_HIGH_MEMORY]))
> + return CONSTRAINT_MEMORY_POLICY;
> + }
Although a nodemask_t was previously allocated on the stack, we should
probably change this to use NODEMASK_ALLOC() for kernels with higher
CONFIG_NODES_SHIFT since allocations can happen very deep into the stack.
There should be a way around that, however. Shouldn't
if (nodes_subset(node_states[N_HIGH_MEMORY], *nodemask))
return CONSTRAINT_MEMORY_POLICY;
be sufficient?
> +
> + /* 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;
>
> - if (!nodes_empty(nodes))
> - return CONSTRAINT_MEMORY_POLICY;
> -#endif
> + /* __GFP_THISNODE never calls OOM.*/
>
> return CONSTRAINT_NONE;
> }
> +#else
> +static inline 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 +621,8 @@ 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;
> @@ -622,11 +641,12 @@ 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) {
> case CONSTRAINT_MEMORY_POLICY:
> + /* kill by process's its own memory alloc limitation */
I don't understand this comment.
> oom_kill_process(current, gfp_mask, order, 0, NULL,
> "No available memory (MPOL_BIND)");
> break;
> Index: mm-test-kernel/mm/page_alloc.c
> ===================================================================
> --- mm-test-kernel.orig/mm/page_alloc.c
> +++ mm-test-kernel/mm/page_alloc.c
> @@ -1667,9 +1667,15 @@ __alloc_pages_may_oom(gfp_t gfp_mask, un
> /* The OOM killer will not help higher order allocs */
> if (order > PAGE_ALLOC_COSTLY_ORDER && !(gfp_mask & __GFP_NOFAIL))
> goto out;
> -
> + /*
> + * In usual, GFP_THISNODE contains __GFP_NORETRY and we never hit this.
> + * Sanity check for bare calls of __GFP_THISNODE, not real OOM.
> + * 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);
This doesn't seem like the right place for this check; should we even try
direct reclaim for bare users of __GFP_THISNODE? If we're adding it for
sanity even though no callers would currently hit it, it also is a
potential escape route for __GFP_NOFAIL.
--
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