[PATCH 3/4] mm, oom: organize oom context into struct

From: Michal Hocko
Date: Wed Jul 08 2015 - 09:05:34 EST

From: David Rientjes <rientjes@xxxxxxxxxx>

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

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

This patch introduces no functional change.

[mhocko@xxxxxxx: s@oom_control@oom_context@]
[mhocko@xxxxxxx: do not initialize on stack oom_context with NULL or 0]
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
---
drivers/tty/sysrq.c | 10 ++++-
include/linux/oom.h | 25 +++++++-----
mm/memcontrol.c | 13 +++---
mm/oom_kill.c | 115 +++++++++++++++++++++++-----------------------------
mm/page_alloc.c | 9 +++-
5 files changed, 89 insertions(+), 83 deletions(-)

diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index b20d2c0ec451..865b837a9aee 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -356,9 +356,15 @@ 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_context oc = {
+ .zonelist = node_zonelist(first_memory_node, gfp_mask),
+ .gfp_mask = gfp_mask,
+ .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..094407cb2d2e 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_context {
+ 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_context *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_context *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_context *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_context *oc);

extern void exit_oom_victim(void);

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index acb93c554f6e..7ad5352bd3f0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1545,6 +1545,10 @@ 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_context oc = {
+ .gfp_mask = gfp_mask,
+ .order = order,
+ };
struct mem_cgroup *iter;
unsigned long chosen_points = 0;
unsigned long totalpages;
@@ -1563,7 +1567,7 @@ 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 +1575,7 @@ 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 +1613,8 @@ 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 0b1b0b25f928..01aa4cb86857 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_context *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_context *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_context *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_context *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_context *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_context *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_context *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_context
*
* 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_context *oc)
{
- const nodemask_t *mpol_mask;
struct task_struct *p;
unsigned long totalpages;
unsigned long freed = 0;
@@ -661,7 +647,7 @@ bool out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
if (oom_killer_disabled)
return false;

- if (!force_kill) {
+ if (!oc->force_kill) {
blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
if (freed > 0)
/* Got some memory back in the last second. */
@@ -686,39 +672,38 @@ 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;
- if (!force_kill)
- check_panic_on_oom(constraint, gfp_mask, order, mpol_mask, NULL);
+ constraint = constrained_alloc(oc, &totalpages);
+ if (constraint != CONSTRAINT_MEMORY_POLICY)
+ oc->nodemask = NULL;
+ if (!oc->force_kill)
+ check_panic_on_oom(oc, constraint, NULL);

/*
* not affecting force_kill because sysrq triggered OOM killer runs from
* the workqueue context so current->mm will be 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) {
- if (!force_kill) {
- dump_header(NULL, gfp_mask, order, NULL, mpol_mask);
+ if (!oc->force_kill) {
+ dump_header(oc, NULL, NULL);
panic("Out of memory and no killable processes...\n");
} else {
pr_info("Sysrq triggered out of memory. No killable task found...\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:
@@ -739,13 +724,15 @@ bool out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
*/
void pagefault_out_of_memory(void)
{
+ struct oom_context oc = { 0 };
+
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 1f9ffbb087cb..4b172b4213b5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2680,6 +2680,12 @@ 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_context oc = {
+ .zonelist = ac->zonelist,
+ .nodemask = ac->nodemask,
+ .gfp_mask = gfp_mask,
+ .order = order,
+ };
struct page *page;

*did_some_progress = 0;
@@ -2731,8 +2737,7 @@ __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);
--
2.1.4

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