Commit d977aa93 authored by Chris Down's avatar Chris Down Committed by Linus Torvalds
Browse files

mm, memcg: unify reclaim retry limits with page allocator 



Reclaim retries have been set to 5 since the beginning of time in
commit 66e1707b ("Memory controller: add per cgroup LRU and
reclaim").  However, we now have a generally agreed-upon standard for
page reclaim: MAX_RECLAIM_RETRIES (currently 16), added many years later
in commit 0a0337e0 ("mm, oom: rework oom detection").

In the absence of a compelling reason to declare an OOM earlier in memcg
context than page allocator context, it seems reasonable to supplant
MEM_CGROUP_RECLAIM_RETRIES with MAX_RECLAIM_RETRIES, making the page
allocator and memcg internals more similar in semantics when reclaim
fails to produce results, avoiding premature OOMs or throttling.

Signed-off-by: default avatarChris Down <chris@chrisdown.name>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Link: http://lkml.kernel.org/r/da557856c9c7654308eaff4eedc1952a95e8df5f.1594640214.git.chris@chrisdown.name


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b3ff9291

mm/memcontrol.c

+6 −9
Original line number Diff line number Diff line
@@ -73,9 +73,6 @@ EXPORT_SYMBOL(memory_cgrp_subsys); 


struct mem_cgroup *root_mem_cgroup __read_mostly;



/* The number of times we should retry reclaim failures before giving up. */

#define MEM_CGROUP_RECLAIM_RETRIES	5



/* Socket memory accounting disabled? */

static bool cgroup_memory_nosocket;
@@ -2538,7 +2535,7 @@ void mem_cgroup_handle_over_high(void) 
	unsigned long pflags;

	unsigned long nr_reclaimed;

	unsigned int nr_pages = current->memcg_nr_pages_over_high;

	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;

	int nr_retries = MAX_RECLAIM_RETRIES;

	struct mem_cgroup *memcg;

	bool in_retry = false;
@@ -2615,7 +2612,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, 
		      unsigned int nr_pages)

{

	unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages);

	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;

	int nr_retries = MAX_RECLAIM_RETRIES;

	struct mem_cgroup *mem_over_limit;

	struct page_counter *counter;

	unsigned long nr_reclaimed;
@@ -2734,7 +2731,7 @@ retry: 
		       get_order(nr_pages * PAGE_SIZE));

	switch (oom_status) {

	case OOM_SUCCESS:

		nr_retries = MEM_CGROUP_RECLAIM_RETRIES;

		nr_retries = MAX_RECLAIM_RETRIES;

		goto retry;

	case OOM_FAILED:

		goto force;
@@ -3414,7 +3411,7 @@ static inline bool memcg_has_children(struct mem_cgroup *memcg) 
 */

static int mem_cgroup_force_empty(struct mem_cgroup *memcg)

{

	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;

	int nr_retries = MAX_RECLAIM_RETRIES;



	/* we call try-to-free pages for make this cgroup empty */

	lru_add_drain_all();
@@ -6235,7 +6232,7 @@ static ssize_t memory_high_write(struct kernfs_open_file *of, 
				 char *buf, size_t nbytes, loff_t off)

{

	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));

	unsigned int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;

	unsigned int nr_retries = MAX_RECLAIM_RETRIES;

	bool drained = false;

	unsigned long high;

	int err;
@@ -6283,7 +6280,7 @@ static ssize_t memory_max_write(struct kernfs_open_file *of, 
				char *buf, size_t nbytes, loff_t off)

{

	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));

	unsigned int nr_reclaims = MEM_CGROUP_RECLAIM_RETRIES;

	unsigned int nr_reclaims = MAX_RECLAIM_RETRIES;

	bool drained = false;

	unsigned long max;

	int err;

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