Re: [patch v2 1/3] mm, oom: organize oom context into struct

[Hillf Danton]

> Subject: [patch v2 1/3] mm, oom: organize oom context into struct
[patch v2 2/3] mm, oom: organize oom context into struct
[patch v2 3/3] mm, oom: organize oom context into struct

I am wondering if a redelivery is needed for the same 3 subject lines.

Hillf
> 
> 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.
> 
> Acked-by: Michal Hocko <mhocko@xxxxxxx>
> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
> ---
>  v2: fix changelog typo per Sergey
> 
>  drivers/tty/sysrq.c |  12 +++++-
>  include/linux/oom.h |  25 +++++++-----
>  mm/memcontrol.c     |  16 +++++---
>  mm/oom_kill.c       | 115 ++++++++++++++++++++++++----------------------------
>  mm/page_alloc.c     |  10 ++++-
>  5 files changed, 98 insertions(+), 80 deletions(-)
> 
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> --- 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
> --- 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
> --- 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
> --- 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
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2680,6 +2680,13 @@ 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;
> @@ -2731,8 +2738,7 @@ __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);
> --
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