Re: [PATCH] slub: consider pfmemalloc_match() in get_partial_node()
On Sat, 25 Aug 2012, Joonsoo Kim wrote: > There is no consideration for pfmemalloc_match() in get_partial(). If we don't > consider that, we can't restrict access to PFMEMALLOC page mostly. > > We may encounter following scenario. > > Assume there is a request from normal allocation > and there is no objects in per cpu cache and no node partial slab. > > In this case, slab_alloc go into slow-path and > new_slab_objects() is invoked. It may return PFMEMALLOC page. > Current user is not allowed to access PFMEMALLOC page, > deactivate_slab() is called (commit 5091b74a95d447e34530e713a8971450a45498b3), > then return object from PFMEMALLOC page. > > Next time, when we meet another request from normal allocation, > slab_alloc() go into slow-path and re-go new_slab_objects(). > In new_slab_objects(), we invoke get_partial() and we get a partial slab > which we have been deactivated just before, that is, PFMEMALLOC page. > We extract one object from it and re-deactivate. > > "deactivate -> re-get in get_partial -> re-deactivate" occures repeatedly. > > As a result, we can't restrict access to PFMEMALLOC page and > moreover, it introduce much performance degration to normal allocation > because of deactivation frequently. > > Now, we need to consider pfmemalloc_match() in get_partial_node() > It prevent "deactivate -> re-get in get_partial". > Instead, new_slab() is called. It may return !PFMEMALLOC page, > so above situation will be suspended sometime. > > Signed-off-by: Joonsoo Kim > Cc: David Miller > Cc: Neil Brown > Cc: Peter Zijlstra > Cc: Mike Christie > Cc: Eric B Munson > Cc: Eric Dumazet > Cc: Sebastian Andrzej Siewior > Cc: Mel Gorman > Cc: Christoph Lameter > Cc: Andrew Morton Acked-by: David Rientjes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] slub: consider pfmemalloc_match() in get_partial_node()
On Sat, 25 Aug 2012, Joonsoo Kim wrote: There is no consideration for pfmemalloc_match() in get_partial(). If we don't consider that, we can't restrict access to PFMEMALLOC page mostly. We may encounter following scenario. Assume there is a request from normal allocation and there is no objects in per cpu cache and no node partial slab. In this case, slab_alloc go into slow-path and new_slab_objects() is invoked. It may return PFMEMALLOC page. Current user is not allowed to access PFMEMALLOC page, deactivate_slab() is called (commit 5091b74a95d447e34530e713a8971450a45498b3), then return object from PFMEMALLOC page. Next time, when we meet another request from normal allocation, slab_alloc() go into slow-path and re-go new_slab_objects(). In new_slab_objects(), we invoke get_partial() and we get a partial slab which we have been deactivated just before, that is, PFMEMALLOC page. We extract one object from it and re-deactivate. deactivate - re-get in get_partial - re-deactivate occures repeatedly. As a result, we can't restrict access to PFMEMALLOC page and moreover, it introduce much performance degration to normal allocation because of deactivation frequently. Now, we need to consider pfmemalloc_match() in get_partial_node() It prevent deactivate - re-get in get_partial. Instead, new_slab() is called. It may return !PFMEMALLOC page, so above situation will be suspended sometime. Signed-off-by: Joonsoo Kim js1...@gmail.com Cc: David Miller da...@davemloft.net Cc: Neil Brown ne...@suse.de Cc: Peter Zijlstra a.p.zijls...@chello.nl Cc: Mike Christie micha...@cs.wisc.edu Cc: Eric B Munson emun...@mgebm.net Cc: Eric Dumazet eric.duma...@gmail.com Cc: Sebastian Andrzej Siewior sebast...@breakpoint.cc Cc: Mel Gorman mgor...@suse.de Cc: Christoph Lameter c...@linux-foundation.org Cc: Andrew Morton a...@linux-foundation.org Acked-by: David Rientjes rient...@google.com -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] slub: consider pfmemalloc_match() in get_partial_node()
There is no consideration for pfmemalloc_match() in get_partial(). If we don't
consider that, we can't restrict access to PFMEMALLOC page mostly.
We may encounter following scenario.
Assume there is a request from normal allocation
and there is no objects in per cpu cache and no node partial slab.
In this case, slab_alloc go into slow-path and
new_slab_objects() is invoked. It may return PFMEMALLOC page.
Current user is not allowed to access PFMEMALLOC page,
deactivate_slab() is called (commit 5091b74a95d447e34530e713a8971450a45498b3),
then return object from PFMEMALLOC page.
Next time, when we meet another request from normal allocation,
slab_alloc() go into slow-path and re-go new_slab_objects().
In new_slab_objects(), we invoke get_partial() and we get a partial slab
which we have been deactivated just before, that is, PFMEMALLOC page.
We extract one object from it and re-deactivate.
"deactivate -> re-get in get_partial -> re-deactivate" occures repeatedly.
As a result, we can't restrict access to PFMEMALLOC page and
moreover, it introduce much performance degration to normal allocation
because of deactivation frequently.
Now, we need to consider pfmemalloc_match() in get_partial_node()
It prevent "deactivate -> re-get in get_partial".
Instead, new_slab() is called. It may return !PFMEMALLOC page,
so above situation will be suspended sometime.
Signed-off-by: Joonsoo Kim
Cc: David Miller
Cc: Neil Brown
Cc: Peter Zijlstra
Cc: Mike Christie
Cc: Eric B Munson
Cc: Eric Dumazet
Cc: Sebastian Andrzej Siewior
Cc: Mel Gorman
Cc: Christoph Lameter
Cc: Andrew Morton
---
This patch based on Pekka's slab/next tree with my two patches.
[PATCH 1/2] slub: rename cpu_partial to max_cpu_object
https://lkml.org/lkml/2012/8/24/293
[PATCH 2/2] slub: correct the calculation of the number of cpu objects in
get_partial_node
https://lkml.org/lkml/2012/8/24/290
diff --git a/mm/slub.c b/mm/slub.c
index c96e0e4..a21da3a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1529,12 +1529,13 @@ static inline void *acquire_slab(struct kmem_cache *s,
}
static int put_cpu_partial(struct kmem_cache *s, struct page *page, int drain);
+static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags);
/*
* Try to allocate a partial slab from a specific node.
*/
-static void *get_partial_node(struct kmem_cache *s,
- struct kmem_cache_node *n, struct kmem_cache_cpu *c)
+static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
+ struct kmem_cache_cpu *c, gfp_t flags)
{
struct page *page, *page2;
void *object = NULL;
@@ -1551,8 +1552,12 @@ static void *get_partial_node(struct kmem_cache *s,
spin_lock(>list_lock);
list_for_each_entry_safe(page, page2, >partial, lru) {
- void *t = acquire_slab(s, n, page, object == NULL);
+ void *t;
+ if (!pfmemalloc_match(page, flags))
+ continue;
+
+ t = acquire_slab(s, n, page, object == NULL);
if (!t)
break;
@@ -1620,7 +1625,7 @@ static void *get_any_partial(struct kmem_cache *s, gfp_t
flags,
if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
n->nr_partial > s->min_partial) {
- object = get_partial_node(s, n, c);
+ object = get_partial_node(s, n, c, flags);
if (object) {
/*
* Return the object even if
@@ -1649,7 +1654,7 @@ static void *get_partial(struct kmem_cache *s, gfp_t
flags, int node,
void *object;
int searchnode = (node == NUMA_NO_NODE) ? numa_node_id() : node;
- object = get_partial_node(s, get_node(s, searchnode), c);
+ object = get_partial_node(s, get_node(s, searchnode), c, flags);
if (object || node != NUMA_NO_NODE)
return object;
--
1.7.9.5
--
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Please read the FAQ at http://www.tux.org/lkml/
[PATCH] slub: consider pfmemalloc_match() in get_partial_node()
There is no consideration for pfmemalloc_match() in get_partial(). If we don't
consider that, we can't restrict access to PFMEMALLOC page mostly.
We may encounter following scenario.
Assume there is a request from normal allocation
and there is no objects in per cpu cache and no node partial slab.
In this case, slab_alloc go into slow-path and
new_slab_objects() is invoked. It may return PFMEMALLOC page.
Current user is not allowed to access PFMEMALLOC page,
deactivate_slab() is called (commit 5091b74a95d447e34530e713a8971450a45498b3),
then return object from PFMEMALLOC page.
Next time, when we meet another request from normal allocation,
slab_alloc() go into slow-path and re-go new_slab_objects().
In new_slab_objects(), we invoke get_partial() and we get a partial slab
which we have been deactivated just before, that is, PFMEMALLOC page.
We extract one object from it and re-deactivate.
deactivate - re-get in get_partial - re-deactivate occures repeatedly.
As a result, we can't restrict access to PFMEMALLOC page and
moreover, it introduce much performance degration to normal allocation
because of deactivation frequently.
Now, we need to consider pfmemalloc_match() in get_partial_node()
It prevent deactivate - re-get in get_partial.
Instead, new_slab() is called. It may return !PFMEMALLOC page,
so above situation will be suspended sometime.
Signed-off-by: Joonsoo Kim js1...@gmail.com
Cc: David Miller da...@davemloft.net
Cc: Neil Brown ne...@suse.de
Cc: Peter Zijlstra a.p.zijls...@chello.nl
Cc: Mike Christie micha...@cs.wisc.edu
Cc: Eric B Munson emun...@mgebm.net
Cc: Eric Dumazet eric.duma...@gmail.com
Cc: Sebastian Andrzej Siewior sebast...@breakpoint.cc
Cc: Mel Gorman mgor...@suse.de
Cc: Christoph Lameter c...@linux-foundation.org
Cc: Andrew Morton a...@linux-foundation.org
---
This patch based on Pekka's slab/next tree with my two patches.
[PATCH 1/2] slub: rename cpu_partial to max_cpu_object
https://lkml.org/lkml/2012/8/24/293
[PATCH 2/2] slub: correct the calculation of the number of cpu objects in
get_partial_node
https://lkml.org/lkml/2012/8/24/290
diff --git a/mm/slub.c b/mm/slub.c
index c96e0e4..a21da3a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1529,12 +1529,13 @@ static inline void *acquire_slab(struct kmem_cache *s,
}
static int put_cpu_partial(struct kmem_cache *s, struct page *page, int drain);
+static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags);
/*
* Try to allocate a partial slab from a specific node.
*/
-static void *get_partial_node(struct kmem_cache *s,
- struct kmem_cache_node *n, struct kmem_cache_cpu *c)
+static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
+ struct kmem_cache_cpu *c, gfp_t flags)
{
struct page *page, *page2;
void *object = NULL;
@@ -1551,8 +1552,12 @@ static void *get_partial_node(struct kmem_cache *s,
spin_lock(n-list_lock);
list_for_each_entry_safe(page, page2, n-partial, lru) {
- void *t = acquire_slab(s, n, page, object == NULL);
+ void *t;
+ if (!pfmemalloc_match(page, flags))
+ continue;
+
+ t = acquire_slab(s, n, page, object == NULL);
if (!t)
break;
@@ -1620,7 +1625,7 @@ static void *get_any_partial(struct kmem_cache *s, gfp_t
flags,
if (n cpuset_zone_allowed_hardwall(zone, flags)
n-nr_partial s-min_partial) {
- object = get_partial_node(s, n, c);
+ object = get_partial_node(s, n, c, flags);
if (object) {
/*
* Return the object even if
@@ -1649,7 +1654,7 @@ static void *get_partial(struct kmem_cache *s, gfp_t
flags, int node,
void *object;
int searchnode = (node == NUMA_NO_NODE) ? numa_node_id() : node;
- object = get_partial_node(s, get_node(s, searchnode), c);
+ object = get_partial_node(s, get_node(s, searchnode), c, flags);
if (object || node != NUMA_NO_NODE)
return object;
--
1.7.9.5
--
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