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Date: Thu, 2 Jul 2015 08:00:42 +0200
From: Michal Hocko <mhocko@...e.cz>
To: David Rientjes <rientjes@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [patch v2 1/3] mm, oom: organize oom context into struct
JFYI. I have added this patch of yours into my series which is fixing
other sysrq+f issue and it is waiting for the merge window to close.
On Wed 01-07-15 14:37:07, David Rientjes wrote:
> 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@...e.cz>
> Signed-off-by: David Rientjes <rientjes@...gle.com>
> ---
> 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);
--
Michal Hocko
SUSE Labs
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