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-rw-r--r--include/linux/cpuset.h47
-rw-r--r--include/linux/init_task.h8
-rw-r--r--include/linux/sched.h2
-rw-r--r--kernel/cpuset.c43
-rw-r--r--kernel/fork.c1
-rw-r--r--mm/filemap.c11
-rw-r--r--mm/hugetlb.c15
-rw-r--r--mm/mempolicy.c28
-rw-r--r--mm/page_alloc.c33
-rw-r--r--mm/slab.c13
-rw-r--r--mm/slub.c40
-rw-r--r--mm/vmscan.c2
12 files changed, 133 insertions, 110 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index e9eaec522655..7a7e5fd2a277 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -89,42 +89,33 @@ extern void rebuild_sched_domains(void);
extern void cpuset_print_task_mems_allowed(struct task_struct *p);
/*
- * reading current mems_allowed and mempolicy in the fastpath must protected
- * by get_mems_allowed()
+ * get_mems_allowed is required when making decisions involving mems_allowed
+ * such as during page allocation. mems_allowed can be updated in parallel
+ * and depending on the new value an operation can fail potentially causing
+ * process failure. A retry loop with get_mems_allowed and put_mems_allowed
+ * prevents these artificial failures.
*/
-static inline void get_mems_allowed(void)
+static inline unsigned int get_mems_allowed(void)
{
- current->mems_allowed_change_disable++;
-
- /*
- * ensure that reading mems_allowed and mempolicy happens after the
- * update of ->mems_allowed_change_disable.
- *
- * the write-side task finds ->mems_allowed_change_disable is not 0,
- * and knows the read-side task is reading mems_allowed or mempolicy,
- * so it will clear old bits lazily.
- */
- smp_mb();
+ return read_seqcount_begin(&current->mems_allowed_seq);
}
-static inline void put_mems_allowed(void)
+/*
+ * If this returns false, the operation that took place after get_mems_allowed
+ * may have failed. It is up to the caller to retry the operation if
+ * appropriate.
+ */
+static inline bool put_mems_allowed(unsigned int seq)
{
- /*
- * ensure that reading mems_allowed and mempolicy before reducing
- * mems_allowed_change_disable.
- *
- * the write-side task will know that the read-side task is still
- * reading mems_allowed or mempolicy, don't clears old bits in the
- * nodemask.
- */
- smp_mb();
- --ACCESS_ONCE(current->mems_allowed_change_disable);
+ return !read_seqcount_retry(&current->mems_allowed_seq, seq);
}
static inline void set_mems_allowed(nodemask_t nodemask)
{
task_lock(current);
+ write_seqcount_begin(&current->mems_allowed_seq);
current->mems_allowed = nodemask;
+ write_seqcount_end(&current->mems_allowed_seq);
task_unlock(current);
}
@@ -234,12 +225,14 @@ static inline void set_mems_allowed(nodemask_t nodemask)
{
}
-static inline void get_mems_allowed(void)
+static inline unsigned int get_mems_allowed(void)
{
+ return 0;
}
-static inline void put_mems_allowed(void)
+static inline bool put_mems_allowed(unsigned int seq)
{
+ return true;
}
#endif /* !CONFIG_CPUSETS */
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index f994d51f70f2..e4baff5f7ff4 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -29,6 +29,13 @@ extern struct fs_struct init_fs;
#define INIT_GROUP_RWSEM(sig)
#endif
+#ifdef CONFIG_CPUSETS
+#define INIT_CPUSET_SEQ \
+ .mems_allowed_seq = SEQCNT_ZERO,
+#else
+#define INIT_CPUSET_SEQ
+#endif
+
#define INIT_SIGNALS(sig) { \
.nr_threads = 1, \
.wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\
@@ -192,6 +199,7 @@ extern struct cred init_cred;
INIT_FTRACE_GRAPH \
INIT_TRACE_RECURSION \
INIT_TASK_RCU_PREEMPT(tsk) \
+ INIT_CPUSET_SEQ \
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e074e1e54f85..0c147a4260a5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1514,7 +1514,7 @@ struct task_struct {
#endif
#ifdef CONFIG_CPUSETS
nodemask_t mems_allowed; /* Protected by alloc_lock */
- int mems_allowed_change_disable;
+ seqcount_t mems_allowed_seq; /* Seqence no to catch updates */
int cpuset_mem_spread_rotor;
int cpuset_slab_spread_rotor;
#endif
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 5d575836dba6..1010cc61931f 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -964,7 +964,6 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk,
{
bool need_loop;
-repeat:
/*
* Allow tasks that have access to memory reserves because they have
* been OOM killed to get memory anywhere.
@@ -983,45 +982,19 @@ repeat:
*/
need_loop = task_has_mempolicy(tsk) ||
!nodes_intersects(*newmems, tsk->mems_allowed);
- nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
- mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
- /*
- * ensure checking ->mems_allowed_change_disable after setting all new
- * allowed nodes.
- *
- * the read-side task can see an nodemask with new allowed nodes and
- * old allowed nodes. and if it allocates page when cpuset clears newly
- * disallowed ones continuous, it can see the new allowed bits.
- *
- * And if setting all new allowed nodes is after the checking, setting
- * all new allowed nodes and clearing newly disallowed ones will be done
- * continuous, and the read-side task may find no node to alloc page.
- */
- smp_mb();
+ if (need_loop)
+ write_seqcount_begin(&tsk->mems_allowed_seq);
- /*
- * Allocation of memory is very fast, we needn't sleep when waiting
- * for the read-side.
- */
- while (need_loop && ACCESS_ONCE(tsk->mems_allowed_change_disable)) {
- task_unlock(tsk);
- if (!task_curr(tsk))
- yield();
- goto repeat;
- }
-
- /*
- * ensure checking ->mems_allowed_change_disable before clearing all new
- * disallowed nodes.
- *
- * if clearing newly disallowed bits before the checking, the read-side
- * task may find no node to alloc page.
- */
- smp_mb();
+ nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
+ mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
tsk->mems_allowed = *newmems;
+
+ if (need_loop)
+ write_seqcount_end(&tsk->mems_allowed_seq);
+
task_unlock(tsk);
}
diff --git a/kernel/fork.c b/kernel/fork.c
index a9e99f3c18e0..9cc227d54102 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1237,6 +1237,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
#ifdef CONFIG_CPUSETS
p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
+ seqcount_init(&p->mems_allowed_seq);
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
p->irq_events = 0;
diff --git a/mm/filemap.c b/mm/filemap.c
index f3230604006c..843042045dc9 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -499,10 +499,13 @@ struct page *__page_cache_alloc(gfp_t gfp)
struct page *page;
if (cpuset_do_page_mem_spread()) {
- get_mems_allowed();
- n = cpuset_mem_spread_node();
- page = alloc_pages_exact_node(n, gfp, 0);
- put_mems_allowed();
+ unsigned int cpuset_mems_cookie;
+ do {
+ cpuset_mems_cookie = get_mems_allowed();
+ n = cpuset_mem_spread_node();
+ page = alloc_pages_exact_node(n, gfp, 0);
+ } while (!put_mems_allowed(cpuset_mems_cookie) && !page);
+
return page;
}
return alloc_pages(gfp, 0);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 62f9fada4d6d..b1c314877334 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -454,14 +454,16 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
struct vm_area_struct *vma,
unsigned long address, int avoid_reserve)
{
- struct page *page = NULL;
+ struct page *page;
struct mempolicy *mpol;
nodemask_t *nodemask;
struct zonelist *zonelist;
struct zone *zone;
struct zoneref *z;
+ unsigned int cpuset_mems_cookie;
- get_mems_allowed();
+retry_cpuset:
+ cpuset_mems_cookie = get_mems_allowed();
zonelist = huge_zonelist(vma, address,
htlb_alloc_mask, &mpol, &nodemask);
/*
@@ -488,10 +490,15 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
}
}
}
-err:
+
mpol_cond_put(mpol);
- put_mems_allowed();
+ if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+ goto retry_cpuset;
return page;
+
+err:
+ mpol_cond_put(mpol);
+ return NULL;
}
static void update_and_free_page(struct hstate *h, struct page *page)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 71e1a523e209..cfb6c8678754 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1850,18 +1850,24 @@ struct page *
alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
unsigned long addr, int node)
{
- struct mempolicy *pol = get_vma_policy(current, vma, addr);
+ struct mempolicy *pol;
struct zonelist *zl;
struct page *page;
+ unsigned int cpuset_mems_cookie;
+
+retry_cpuset:
+ pol = get_vma_policy(current, vma, addr);
+ cpuset_mems_cookie = get_mems_allowed();
- get_mems_allowed();
if (unlikely(pol->mode == MPOL_INTERLEAVE)) {
unsigned nid;
nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
mpol_cond_put(pol);
page = alloc_page_interleave(gfp, order, nid);
- put_mems_allowed();
+ if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+ goto retry_cpuset;
+
return page;
}
zl = policy_zonelist(gfp, pol, node);
@@ -1872,7 +1878,8 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
struct page *page = __alloc_pages_nodemask(gfp, order,
zl, policy_nodemask(gfp, pol));
__mpol_put(pol);
- put_mems_allowed();
+ if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+ goto retry_cpuset;
return page;
}
/*
@@ -1880,7 +1887,8 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
*/
page = __alloc_pages_nodemask(gfp, order, zl,
policy_nodemask(gfp, pol));
- put_mems_allowed();
+ if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+ goto retry_cpuset;
return page;
}
@@ -1907,11 +1915,14 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order)
{
struct mempolicy *pol = current->mempolicy;
struct page *page;
+ unsigned int cpuset_mems_cookie;
if (!pol || in_interrupt() || (gfp & __GFP_THISNODE))
pol = &default_policy;
- get_mems_allowed();
+retry_cpuset:
+ cpuset_mems_cookie = get_mems_allowed();
+
/*
* No reference counting needed for current->mempolicy
* nor system default_policy
@@ -1922,7 +1933,10 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order)
page = __alloc_pages_nodemask(gfp, order,
policy_zonelist(gfp, pol, numa_node_id()),
policy_nodemask(gfp, pol));
- put_mems_allowed();
+
+ if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+ goto retry_cpuset;
+
return page;
}
EXPORT_SYMBOL(alloc_pages_current);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 673596ad9c80..40de6854b980 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2380,8 +2380,9 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
{
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
struct zone *preferred_zone;
- struct page *page;
+ struct page *page = NULL;
int migratetype = allocflags_to_migratetype(gfp_mask);
+ unsigned int cpuset_mems_cookie;
gfp_mask &= gfp_allowed_mask;
@@ -2400,15 +2401,15 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
if (unlikely(!zonelist->_zonerefs->zone))
return NULL;
- get_mems_allowed();
+retry_cpuset:
+ cpuset_mems_cookie = get_mems_allowed();
+
/* The preferred zone is used for statistics later */
first_zones_zonelist(zonelist, high_zoneidx,
nodemask ? : &cpuset_current_mems_allowed,
&preferred_zone);
- if (!preferred_zone) {
- put_mems_allowed();
- return NULL;
- }
+ if (!preferred_zone)
+ goto out;
/* First allocation attempt */
page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
@@ -2418,9 +2419,19 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
page = __alloc_pages_slowpath(gfp_mask, order,
zonelist, high_zoneidx, nodemask,
preferred_zone, migratetype);
- put_mems_allowed();
trace_mm_page_alloc(page, order, gfp_mask, migratetype);
+
+out:
+ /*
+ * When updating a task's mems_allowed, it is possible to race with
+ * parallel threads in such a way that an allocation can fail while
+ * the mask is being updated. If a page allocation is about to fail,
+ * check if the cpuset changed during allocation and if so, retry.
+ */
+ if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+ goto retry_cpuset;
+
return page;
}
EXPORT_SYMBOL(__alloc_pages_nodemask);
@@ -2634,13 +2645,15 @@ void si_meminfo_node(struct sysinfo *val, int nid)
bool skip_free_areas_node(unsigned int flags, int nid)
{
bool ret = false;
+ unsigned int cpuset_mems_cookie;
if (!(flags & SHOW_MEM_FILTER_NODES))
goto out;
- get_mems_allowed();
- ret = !node_isset(nid, cpuset_current_mems_allowed);
- put_mems_allowed();
+ do {
+ cpuset_mems_cookie = get_mems_allowed();
+ ret = !node_isset(nid, cpuset_current_mems_allowed);
+ } while (!put_mems_allowed(cpuset_mems_cookie));
out:
return ret;
}
diff --git a/mm/slab.c b/mm/slab.c
index f0bd7857ab3b..29c8716eb7a9 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3284,12 +3284,10 @@ static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
if (in_interrupt() || (flags & __GFP_THISNODE))
return NULL;
nid_alloc = nid_here = numa_mem_id();
- get_mems_allowed();
if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
nid_alloc = cpuset_slab_spread_node();
else if (current->mempolicy)
nid_alloc = slab_node(current->mempolicy);
- put_mems_allowed();
if (nid_alloc != nid_here)
return ____cache_alloc_node(cachep, flags, nid_alloc);
return NULL;
@@ -3312,14 +3310,17 @@ static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
enum zone_type high_zoneidx = gfp_zone(flags);
void *obj = NULL;
int nid;
+ unsigned int cpuset_mems_cookie;
if (flags & __GFP_THISNODE)
return NULL;
- get_mems_allowed();
- zonelist = node_zonelist(slab_node(current->mempolicy), flags);
local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
+retry_cpuset:
+ cpuset_mems_cookie = get_mems_allowed();
+ zonelist = node_zonelist(slab_node(current->mempolicy), flags);
+
retry:
/*
* Look through allowed nodes for objects available
@@ -3372,7 +3373,9 @@ retry:
}
}
}
- put_mems_allowed();
+
+ if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !obj))
+ goto retry_cpuset;
return obj;
}
diff --git a/mm/slub.c b/mm/slub.c
index 4907563ef7ff..f4a6229848fd 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1581,6 +1581,7 @@ static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags,
struct zone *zone;
enum zone_type high_zoneidx = gfp_zone(flags);
void *object;
+ unsigned int cpuset_mems_cookie;
/*
* The defrag ratio allows a configuration of the tradeoffs between
@@ -1604,23 +1605,32 @@ static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags,
get_cycles() % 1024 > s->remote_node_defrag_ratio)
return NULL;
- get_mems_allowed();
- zonelist = node_zonelist(slab_node(current->mempolicy), flags);
- for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
- struct kmem_cache_node *n;
-
- n = get_node(s, zone_to_nid(zone));
-
- if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
- n->nr_partial > s->min_partial) {
- object = get_partial_node(s, n, c);
- if (object) {
- put_mems_allowed();
- return object;
+ do {
+ cpuset_mems_cookie = get_mems_allowed();
+ zonelist = node_zonelist(slab_node(current->mempolicy), flags);
+ for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
+ struct kmem_cache_node *n;
+
+ n = get_node(s, zone_to_nid(zone));
+
+ if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
+ n->nr_partial > s->min_partial) {
+ object = get_partial_node(s, n, c);
+ if (object) {
+ /*
+ * Return the object even if
+ * put_mems_allowed indicated that
+ * the cpuset mems_allowed was
+ * updated in parallel. It's a
+ * harmless race between the alloc
+ * and the cpuset update.
+ */
+ put_mems_allowed(cpuset_mems_cookie);
+ return object;
+ }
}
}
- }
- put_mems_allowed();
+ } while (!put_mems_allowed(cpuset_mems_cookie));
#endif
return NULL;
}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 440af1d899b9..55d86c9506f3 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2343,7 +2343,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
unsigned long writeback_threshold;
bool aborted_reclaim;
- get_mems_allowed();
delayacct_freepages_start();
if (global_reclaim(sc))
@@ -2407,7 +2406,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
out:
delayacct_freepages_end();
- put_mems_allowed();
if (sc->nr_reclaimed)
return sc->nr_reclaimed;
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-30 17:20:37 +0100