mm, oom: organize oom context into struct

There are essential elements to an oom context that are passed around to
multiple functions.

Organize these elements into a new struct, struct oom_control, that
specifies the context for an oom condition.

This patch introduces no functional change.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 98 insertions, 80 deletions

diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index b5b427888b24..ed3e258f4ee9 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -353,9 +353,17 @@ static struct sysrq_key_op sysrq_term_op = {
 
 static void moom_callback(struct work_struct *ignored)
 {
+        const gfp_t gfp_mask = GFP_KERNEL;
+        struct oom_control oc = {
+                .zonelist = node_zonelist(first_memory_node, gfp_mask),
+                .nodemask = NULL,
+                .gfp_mask = gfp_mask,
+                .order = 0,
+                .force_kill = true,
+        };
+
         mutex_lock(&oom_lock);
-        if (!out_of_memory(node_zonelist(first_memory_node, GFP_KERNEL),
-                           GFP_KERNEL, 0, NULL, true))
+        if (!out_of_memory(&oc))
                 pr_info("OOM request ignored because killer is disabled\n");
         mutex_unlock(&oom_lock);
 }
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 7deecb7bca5e..cb29085ded37 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -12,6 +12,14 @@ struct notifier_block;
 struct mem_cgroup;
 struct task_struct;
 
+struct oom_control {
+        struct zonelist *zonelist;
+        nodemask_t      *nodemask;
+        gfp_t           gfp_mask;
+        int             order;
+        bool            force_kill;
+};
+
 /*
  * Types of limitations to the nodes from which allocations may occur
  */
@@ -57,21 +65,18 @@ extern unsigned long oom_badness(struct task_struct *p,
 
 extern int oom_kills_count(void);
 extern void note_oom_kill(void);
-extern void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
+extern void oom_kill_process(struct oom_control *oc, struct task_struct *p,
                              unsigned int points, unsigned long totalpages,
-                             struct mem_cgroup *memcg, nodemask_t *nodemask,
-                             const char *message);
+                             struct mem_cgroup *memcg, const char *message);
 
-extern void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
-                               int order, const nodemask_t *nodemask,
+extern void check_panic_on_oom(struct oom_control *oc,
+                               enum oom_constraint constraint,
                                struct mem_cgroup *memcg);
 
-extern enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
-                unsigned long totalpages, const nodemask_t *nodemask,
-                bool force_kill);
+extern enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
+                struct task_struct *task, unsigned long totalpages);
 
-extern bool out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
-                int order, nodemask_t *mask, bool force_kill);
+extern bool out_of_memory(struct oom_control *oc);
 
 extern void exit_oom_victim(void);
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1af057575ce9..573d90347aa2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1545,6 +1545,13 @@ static unsigned long mem_cgroup_get_limit(struct mem_cgroup *memcg)
 static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
                                      int order)
 {
+        struct oom_control oc = {
+                .zonelist = NULL,
+                .nodemask = NULL,
+                .gfp_mask = gfp_mask,
+                .order = order,
+                .force_kill = false,
+        };
         struct mem_cgroup *iter;
         unsigned long chosen_points = 0;
         unsigned long totalpages;
@@ -1563,7 +1570,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
                 goto unlock;
         }
 
-        check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL, memcg);
+        check_panic_on_oom(&oc, CONSTRAINT_MEMCG, memcg);
         totalpages = mem_cgroup_get_limit(memcg) ? : 1;
         for_each_mem_cgroup_tree(iter, memcg) {
                 struct css_task_iter it;
@@ -1571,8 +1578,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
 
                 css_task_iter_start(&iter->css, &it);
                 while ((task = css_task_iter_next(&it))) {
-                        switch (oom_scan_process_thread(task, totalpages, NULL,
-                                                        false)) {
+                        switch (oom_scan_process_thread(&oc, task, totalpages)) {
                         case OOM_SCAN_SELECT:
                                 if (chosen)
                                         put_task_struct(chosen);
@@ -1610,8 +1616,8 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
 
         if (chosen) {
                 points = chosen_points * 1000 / totalpages;
-                oom_kill_process(chosen, gfp_mask, order, points, totalpages,
-                                 memcg, NULL, "Memory cgroup out of memory");
+                oom_kill_process(&oc, chosen, points, totalpages, memcg,
+                                 "Memory cgroup out of memory");
         }
 unlock:
         mutex_unlock(&oom_lock);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index dff991e0681e..80a7cbd89d66 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -196,27 +196,26 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
  * Determine the type of allocation constraint.
  */
 #ifdef CONFIG_NUMA
-static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
-                                gfp_t gfp_mask, nodemask_t *nodemask,
-                                unsigned long *totalpages)
+static enum oom_constraint constrained_alloc(struct oom_control *oc,
+                                             unsigned long *totalpages)
 {
         struct zone *zone;
         struct zoneref *z;
-        enum zone_type high_zoneidx = gfp_zone(gfp_mask);
+        enum zone_type high_zoneidx = gfp_zone(oc->gfp_mask);
         bool cpuset_limited = false;
         int nid;
 
         /* Default to all available memory */
         *totalpages = totalram_pages + total_swap_pages;
 
-        if (!zonelist)
+        if (!oc->zonelist)
                 return CONSTRAINT_NONE;
         /*
          * 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)
+        if (oc->gfp_mask & __GFP_THISNODE)
                 return CONSTRAINT_NONE;
 
         /*
@@ -224,17 +223,18 @@ static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
          * the page allocator means a mempolicy is in effect.  Cpuset policy
          * is enforced in get_page_from_freelist().
          */
-        if (nodemask && !nodes_subset(node_states[N_MEMORY], *nodemask)) {
+        if (oc->nodemask &&
+            !nodes_subset(node_states[N_MEMORY], *oc->nodemask)) {
                 *totalpages = total_swap_pages;
-                for_each_node_mask(nid, *nodemask)
+                for_each_node_mask(nid, *oc->nodemask)
                         *totalpages += node_spanned_pages(nid);
                 return CONSTRAINT_MEMORY_POLICY;
         }
 
         /* 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(zone, gfp_mask))
+        for_each_zone_zonelist_nodemask(zone, z, oc->zonelist,
+                        high_zoneidx, oc->nodemask)
+                if (!cpuset_zone_allowed(zone, oc->gfp_mask))
                         cpuset_limited = true;
 
         if (cpuset_limited) {
@@ -246,20 +246,18 @@ static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
         return CONSTRAINT_NONE;
 }
 #else
-static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
-                                gfp_t gfp_mask, nodemask_t *nodemask,
-                                unsigned long *totalpages)
+static enum oom_constraint constrained_alloc(struct oom_control *oc,
+                                             unsigned long *totalpages)
 {
         *totalpages = totalram_pages + total_swap_pages;
         return CONSTRAINT_NONE;
 }
 #endif
 
-enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
-                unsigned long totalpages, const nodemask_t *nodemask,
-                bool force_kill)
+enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
+                        struct task_struct *task, unsigned long totalpages)
 {
-        if (oom_unkillable_task(task, NULL, nodemask))
+        if (oom_unkillable_task(task, NULL, oc->nodemask))
                 return OOM_SCAN_CONTINUE;
 
         /*
@@ -267,7 +265,7 @@ enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
          * Don't allow any other task to have access to the reserves.
          */
         if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
-                if (!force_kill)
+                if (!oc->force_kill)
                         return OOM_SCAN_ABORT;
         }
         if (!task->mm)
@@ -280,7 +278,7 @@ enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
         if (oom_task_origin(task))
                 return OOM_SCAN_SELECT;
 
-        if (task_will_free_mem(task) && !force_kill)
+        if (task_will_free_mem(task) && !oc->force_kill)
                 return OOM_SCAN_ABORT;
 
         return OOM_SCAN_OK;
@@ -289,12 +287,9 @@ enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
 /*
  * Simple selection loop. We chose the process with the highest
  * number of 'points'.  Returns -1 on scan abort.
- *
- * (not docbooked, we don't want this one cluttering up the manual)
  */
-static struct task_struct *select_bad_process(unsigned int *ppoints,
-                unsigned long totalpages, const nodemask_t *nodemask,
-                bool force_kill)
+static struct task_struct *select_bad_process(struct oom_control *oc,
+                unsigned int *ppoints, unsigned long totalpages)
 {
         struct task_struct *g, *p;
         struct task_struct *chosen = NULL;
@@ -304,8 +299,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
         for_each_process_thread(g, p) {
                 unsigned int points;
 
-                switch (oom_scan_process_thread(p, totalpages, nodemask,
-                                                force_kill)) {
+                switch (oom_scan_process_thread(oc, p, totalpages)) {
                 case OOM_SCAN_SELECT:
                         chosen = p;
                         chosen_points = ULONG_MAX;
@@ -318,7 +312,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
                 case OOM_SCAN_OK:
                         break;
                 };
-                points = oom_badness(p, NULL, nodemask, totalpages);
+                points = oom_badness(p, NULL, oc->nodemask, totalpages);
                 if (!points || points < chosen_points)
                         continue;
                 /* Prefer thread group leaders for display purposes */
@@ -380,13 +374,13 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
         rcu_read_unlock();
 }
 
-static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
-                        struct mem_cgroup *memcg, const nodemask_t *nodemask)
+static void dump_header(struct oom_control *oc, struct task_struct *p,
+                        struct mem_cgroup *memcg)
 {
         task_lock(current);
         pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
                 "oom_score_adj=%hd\n",
-                current->comm, gfp_mask, order,
+                current->comm, oc->gfp_mask, oc->order,
                 current->signal->oom_score_adj);
         cpuset_print_task_mems_allowed(current);
         task_unlock(current);
@@ -396,7 +390,7 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
         else
                 show_mem(SHOW_MEM_FILTER_NODES);
         if (sysctl_oom_dump_tasks)
-                dump_tasks(memcg, nodemask);
+                dump_tasks(memcg, oc->nodemask);
 }
 
 /*
@@ -487,10 +481,9 @@ void oom_killer_enable(void)
  * Must be called while holding a reference to p, which will be released upon
  * returning.
  */
-void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
+void oom_kill_process(struct oom_control *oc, struct task_struct *p,
                       unsigned int points, unsigned long totalpages,
-                      struct mem_cgroup *memcg, nodemask_t *nodemask,
-                      const char *message)
+                      struct mem_cgroup *memcg, const char *message)
 {
         struct task_struct *victim = p;
         struct task_struct *child;
@@ -514,7 +507,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
         task_unlock(p);
 
         if (__ratelimit(&oom_rs))
-                dump_header(p, gfp_mask, order, memcg, nodemask);
+                dump_header(oc, p, memcg);
 
         task_lock(p);
         pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n",
@@ -537,7 +530,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
                         /*
                          * oom_badness() returns 0 if the thread is unkillable
                          */
-                        child_points = oom_badness(child, memcg, nodemask,
+                        child_points = oom_badness(child, memcg, oc->nodemask,
                                                                 totalpages);
                         if (child_points > victim_points) {
                                 put_task_struct(victim);
@@ -600,8 +593,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 /*
  * Determines whether the kernel must panic because of the panic_on_oom sysctl.
  */
-void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
-                        int order, const nodemask_t *nodemask,
+void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint,
                         struct mem_cgroup *memcg)
 {
         if (likely(!sysctl_panic_on_oom))
@@ -615,7 +607,7 @@ void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
                 if (constraint != CONSTRAINT_NONE)
                         return;
         }
-        dump_header(NULL, gfp_mask, order, memcg, nodemask);
+        dump_header(oc, NULL, memcg);
         panic("Out of memory: %s panic_on_oom is enabled\n",
                 sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
 }
@@ -635,22 +627,16 @@ int unregister_oom_notifier(struct notifier_block *nb)
 EXPORT_SYMBOL_GPL(unregister_oom_notifier);
 
 /**
- * __out_of_memory - kill the "best" process when we run out of memory
- * @zonelist: zonelist pointer
- * @gfp_mask: memory allocation flags
- * @order: amount of memory being requested as a power of 2
- * @nodemask: nodemask passed to page allocator
- * @force_kill: true if a task must be killed, even if others are exiting
+ * out_of_memory - kill the "best" process when we run out of memory
+ * @oc: pointer to struct oom_control
  *
  * If we run out of memory, we have the choice between either
  * killing a random task (bad), letting the system crash (worse)
  * 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.
  */
-bool out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
-                   int order, nodemask_t *nodemask, bool force_kill)
+bool out_of_memory(struct oom_control *oc)
 {
-        const nodemask_t *mpol_mask;
         struct task_struct *p;
         unsigned long totalpages;
         unsigned long freed = 0;
@@ -684,30 +670,29 @@ bool out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
          * Check if there were limitations on the allocation (only relevant for
          * NUMA) that may require different handling.
          */
-        constraint = constrained_alloc(zonelist, gfp_mask, nodemask,
-                                                &totalpages);
-        mpol_mask = (constraint == CONSTRAINT_MEMORY_POLICY) ? nodemask : NULL;
-        check_panic_on_oom(constraint, gfp_mask, order, mpol_mask, NULL);
+        constraint = constrained_alloc(oc, &totalpages);
+        if (constraint != CONSTRAINT_MEMORY_POLICY)
+                oc->nodemask = NULL;
+        check_panic_on_oom(oc, constraint, NULL);
 
         if (sysctl_oom_kill_allocating_task && current->mm &&
-            !oom_unkillable_task(current, NULL, nodemask) &&
+            !oom_unkillable_task(current, NULL, oc->nodemask) &&
             current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
                 get_task_struct(current);
-                oom_kill_process(current, gfp_mask, order, 0, totalpages, NULL,
-                                 nodemask,
+                oom_kill_process(oc, current, 0, totalpages, NULL,
                                  "Out of memory (oom_kill_allocating_task)");
                 goto out;
         }
 
-        p = select_bad_process(&points, totalpages, mpol_mask, force_kill);
+        p = select_bad_process(oc, &points, totalpages);
         /* Found nothing?!?! Either we hang forever, or we panic. */
         if (!p) {
-                dump_header(NULL, gfp_mask, order, NULL, mpol_mask);
+                dump_header(oc, NULL, NULL);
                 panic("Out of memory and no killable processes...\n");
         }
         if (p != (void *)-1UL) {
-                oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,
-                                 nodemask, "Out of memory");
+                oom_kill_process(oc, p, points, totalpages, NULL,
+                                 "Out of memory");
                 killed = 1;
         }
 out:
@@ -728,13 +713,21 @@ out:
  */
 void pagefault_out_of_memory(void)
 {
+        struct oom_control oc = {
+                .zonelist = NULL,
+                .nodemask = NULL,
+                .gfp_mask = 0,
+                .order = 0,
+                .force_kill = false,
+        };
+
         if (mem_cgroup_oom_synchronize(true))
                 return;
 
         if (!mutex_trylock(&oom_lock))
                 return;
 
-        if (!out_of_memory(NULL, 0, 0, NULL, false)) {
+        if (!out_of_memory(&oc)) {
                 /*
                  * There shouldn't be any user tasks runnable while the
                  * OOM killer is disabled, so the current task has to
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index badc7d3bde43..96536144185c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2693,6 +2693,13 @@ static inline struct page *
 __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
         const struct alloc_context *ac, unsigned long *did_some_progress)
 {
+        struct oom_control oc = {
+                .zonelist = ac->zonelist,
+                .nodemask = ac->nodemask,
+                .gfp_mask = gfp_mask,
+                .order = order,
+                .force_kill = false,
+        };
         struct page *page;
 
         *did_some_progress = 0;
@@ -2744,8 +2751,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
                         goto out;
         }
         /* Exhausted what can be done so it's blamo time */
-        if (out_of_memory(ac->zonelist, gfp_mask, order, ac->nodemask, false)
-                        || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL))
+        if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL))
                 *did_some_progress = 1;
 out:
         mutex_unlock(&oom_lock);