* [PATCH] mm, memcg: unify reclaim retry limits with page allocator
@ 2020-05-20 16:31 Chris Down
2020-05-20 16:59 ` Michal Hocko
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Chris Down @ 2020-05-20 16:31 UTC (permalink / raw)
To: Andrew Morton
Cc: Johannes Weiner, Michal Hocko, linux-mm, cgroups, linux-kernel,
kernel-team
Reclaim retries have been set to 5 since the beginning of time in
66e1707bc346 ("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
0a0337e0d1d1 ("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: Chris Down <chris@chrisdown.name>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
---
mm/memcontrol.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b040951ccd6b..d3b23c57bed4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -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;
@@ -2386,7 +2383,7 @@ 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;
if (likely(!nr_pages))
@@ -2438,7 +2435,7 @@ 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;
@@ -2557,7 +2554,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
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;
@@ -3168,7 +3165,7 @@ 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();
@@ -6001,7 +5998,7 @@ 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;
@@ -6049,7 +6046,7 @@ 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;
--
2.26.2
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] mm, memcg: unify reclaim retry limits with page allocator
2020-05-20 16:31 [PATCH] mm, memcg: unify reclaim retry limits with page allocator Chris Down
@ 2020-05-20 16:59 ` Michal Hocko
2020-05-20 23:40 ` Andrew Morton
2020-05-22 14:07 ` Shakeel Butt
2 siblings, 0 replies; 6+ messages in thread
From: Michal Hocko @ 2020-05-20 16:59 UTC (permalink / raw)
To: Chris Down
Cc: Andrew Morton, Johannes Weiner, linux-mm, cgroups, linux-kernel,
kernel-team
On Wed 20-05-20 17:31:42, Chris Down wrote:
> Reclaim retries have been set to 5 since the beginning of time in
> 66e1707bc346 ("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
> 0a0337e0d1d1 ("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: Chris Down <chris@chrisdown.name>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@kernel.org>
I have already expressed my dislike to some of the MEM_CGROUP_RECLAIM_RETRIES
usage but using MAX_RECLAIM_RETRIES is a reasonable thing to do. There
is simply no reason to have two retry limits.
Acked-by: Michal Hocko <mhocko@suse.com>
> ---
> mm/memcontrol.c | 15 ++++++---------
> 1 file changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b040951ccd6b..d3b23c57bed4 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -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;
>
> @@ -2386,7 +2383,7 @@ 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;
>
> if (likely(!nr_pages))
> @@ -2438,7 +2435,7 @@ 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;
> @@ -2557,7 +2554,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
> 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;
> @@ -3168,7 +3165,7 @@ 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();
> @@ -6001,7 +5998,7 @@ 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;
> @@ -6049,7 +6046,7 @@ 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;
> --
> 2.26.2
--
Michal Hocko
SUSE Labs
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] mm, memcg: unify reclaim retry limits with page allocator
2020-05-20 16:31 [PATCH] mm, memcg: unify reclaim retry limits with page allocator Chris Down
2020-05-20 16:59 ` Michal Hocko
@ 2020-05-20 23:40 ` Andrew Morton
2020-05-20 23:42 ` Andrew Morton
2020-05-22 14:07 ` Shakeel Butt
2 siblings, 1 reply; 6+ messages in thread
From: Andrew Morton @ 2020-05-20 23:40 UTC (permalink / raw)
To: Chris Down
Cc: Johannes Weiner, Michal Hocko, linux-mm, cgroups, linux-kernel,
kernel-team
On Wed, 20 May 2020 17:31:42 +0100 Chris Down <chris@chrisdown.name> wrote:
> Reclaim retries have been set to 5 since the beginning of time in
> 66e1707bc346 ("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
> 0a0337e0d1d1 ("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.
>
> ...
>
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -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. */
hm, what tree is this against?
> -#define MEM_CGROUP_RECLAIM_RETRIES 5
> -
> /* Socket memory accounting disabled? */
> static bool cgroup_memory_nosocket;
>
> @@ -2386,7 +2383,7 @@ 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;
I can't seem to find a tree in which mem_cgroup_handle_over_high() has
a local `nr_retries'.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] mm, memcg: unify reclaim retry limits with page allocator
2020-05-20 23:40 ` Andrew Morton
@ 2020-05-20 23:42 ` Andrew Morton
2020-05-20 23:49 ` Chris Down
0 siblings, 1 reply; 6+ messages in thread
From: Andrew Morton @ 2020-05-20 23:42 UTC (permalink / raw)
To: Chris Down, Johannes Weiner, Michal Hocko, linux-mm, cgroups,
linux-kernel, kernel-team
On Wed, 20 May 2020 16:40:37 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
> > -/* The number of times we should retry reclaim failures before giving up. */
>
> hm, what tree is this against?
Ah, my habit of working in reverse time order sometimes does this ;)
I suggest that "mm, memcg: reclaim more aggressively before high
allocator throttling" and this patch become a two-patch series?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mm, memcg: unify reclaim retry limits with page allocator
2020-05-20 23:42 ` Andrew Morton
@ 2020-05-20 23:49 ` Chris Down
0 siblings, 0 replies; 6+ messages in thread
From: Chris Down @ 2020-05-20 23:49 UTC (permalink / raw)
To: Andrew Morton
Cc: Johannes Weiner, Michal Hocko, linux-mm, cgroups, linux-kernel,
kernel-team
Hey Andrew,
Andrew Morton writes:
>Ah, my habit of working in reverse time order sometimes does this ;)
>
>I suggest that "mm, memcg: reclaim more aggressively before high
>allocator throttling" and this patch become a two-patch series?
Sure, they can do (sorry, I meant to add a comment mentioning the dependency,
but forgot). I just didn't want to conflate discussion for both of them, since
they are separate in nature :-)
I'll hold off on sending v2 until the discussion with Michal is finished.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mm, memcg: unify reclaim retry limits with page allocator
2020-05-20 16:31 [PATCH] mm, memcg: unify reclaim retry limits with page allocator Chris Down
2020-05-20 16:59 ` Michal Hocko
2020-05-20 23:40 ` Andrew Morton
@ 2020-05-22 14:07 ` Shakeel Butt
2 siblings, 0 replies; 6+ messages in thread
From: Shakeel Butt @ 2020-05-22 14:07 UTC (permalink / raw)
To: Chris Down
Cc: Andrew Morton, Johannes Weiner, Michal Hocko, Linux MM, Cgroups,
LKML, Kernel Team
On Wed, May 20, 2020 at 9:32 AM Chris Down <chris@chrisdown.name> wrote:
>
> Reclaim retries have been set to 5 since the beginning of time in
> 66e1707bc346 ("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
> 0a0337e0d1d1 ("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: Chris Down <chris@chrisdown.name>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
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2020-05-20 16:31 [PATCH] mm, memcg: unify reclaim retry limits with page allocator Chris Down
2020-05-20 16:59 ` Michal Hocko
2020-05-20 23:40 ` Andrew Morton
2020-05-20 23:42 ` Andrew Morton
2020-05-20 23:49 ` Chris Down
2020-05-22 14:07 ` Shakeel Butt
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