From bdf3c006b9a2308f481ca070d3a85baf1bc5d48f Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Thu, 14 Jan 2016 15:21:40 -0800 Subject: vmstat: make vmstat_updater deferrable again and shut down on idle [ Upstream commit 0eb77e9880321915322d42913c3b53241739c8aa ] Currently the vmstat updater is not deferrable as a result of commit ba4877b9ca51 ("vmstat: do not use deferrable delayed work for vmstat_update"). This in turn can cause multiple interruptions of the applications because the vmstat updater may run at Make vmstate_update deferrable again and provide a function that folds the differentials when the processor is going to idle mode thus addressing the issue of the above commit in a clean way. Note that the shepherd thread will continue scanning the differentials from another processor and will reenable the vmstat workers if it detects any changes. Fixes: ba4877b9ca51 ("vmstat: do not use deferrable delayed work for vmstat_update") Signed-off-by: Christoph Lameter Cc: Michal Hocko Cc: Johannes Weiner Cc: Tetsuo Handa Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- include/linux/vmstat.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h index 3e5d9075960f..73fae8c4a5fb 100644 --- a/include/linux/vmstat.h +++ b/include/linux/vmstat.h @@ -189,6 +189,7 @@ extern void __inc_zone_state(struct zone *, enum zone_stat_item); extern void dec_zone_state(struct zone *, enum zone_stat_item); extern void __dec_zone_state(struct zone *, enum zone_stat_item); +void quiet_vmstat(void); void cpu_vm_stats_fold(int cpu); void refresh_zone_stat_thresholds(void); @@ -249,6 +250,7 @@ static inline void __dec_zone_page_state(struct page *page, static inline void refresh_zone_stat_thresholds(void) { } static inline void cpu_vm_stats_fold(int cpu) { } +static inline void quiet_vmstat(void) { } static inline void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset) { } -- cgit v1.2.3 From dd3351b81fac8a7b431fe636fe35415e35f00fa0 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Sat, 23 Apr 2016 18:26:24 -0400 Subject: Add hlist_add_tail_rcu() (Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net) commit 1602f49b58abcb0d34a5f0a29d68e7c1769547aa upstream. [This commit was a merge, but it added hlist_add_tail_rcu(), which is what we need in this stable tree, so I've changed the subject to be more descriptive - gregkh] Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/linux/rculist.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'include/linux') diff --git a/include/linux/rculist.h b/include/linux/rculist.h index 5ed540986019..a579240c64e9 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -401,6 +401,42 @@ static inline void hlist_add_head_rcu(struct hlist_node *n, first->pprev = &n->next; } +/** + * hlist_add_tail_rcu + * @n: the element to add to the hash list. + * @h: the list to add to. + * + * Description: + * Adds the specified element to the specified hlist, + * while permitting racing traversals. + * + * The caller must take whatever precautions are necessary + * (such as holding appropriate locks) to avoid racing + * with another list-mutation primitive, such as hlist_add_head_rcu() + * or hlist_del_rcu(), running on this same list. + * However, it is perfectly legal to run concurrently with + * the _rcu list-traversal primitives, such as + * hlist_for_each_entry_rcu(), used to prevent memory-consistency + * problems on Alpha CPUs. Regardless of the type of CPU, the + * list-traversal primitive must be guarded by rcu_read_lock(). + */ +static inline void hlist_add_tail_rcu(struct hlist_node *n, + struct hlist_head *h) +{ + struct hlist_node *i, *last = NULL; + + for (i = hlist_first_rcu(h); i; i = hlist_next_rcu(i)) + last = i; + + if (last) { + n->next = last->next; + n->pprev = &last->next; + rcu_assign_pointer(hlist_next_rcu(last), n); + } else { + hlist_add_head_rcu(n, h); + } +} + /** * hlist_add_before_rcu * @n: the new element to add to the hash list. -- cgit v1.2.3