diff options
Diffstat (limited to 'features/rt/mm-memcontrol-Provide-a-local_lock-for-per-CPU-memcg.patch')
| -rw-r--r-- | features/rt/mm-memcontrol-Provide-a-local_lock-for-per-CPU-memcg.patch | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/features/rt/mm-memcontrol-Provide-a-local_lock-for-per-CPU-memcg.patch b/features/rt/mm-memcontrol-Provide-a-local_lock-for-per-CPU-memcg.patch new file mode 100644 index 00000000..d85633ab --- /dev/null +++ b/features/rt/mm-memcontrol-Provide-a-local_lock-for-per-CPU-memcg.patch @@ -0,0 +1,143 @@ +From a597d1d521af35edd6fbb86d1934a0f92bc9d54e Mon Sep 17 00:00:00 2001 +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Tue, 18 Aug 2020 10:30:00 +0200 +Subject: [PATCH 113/191] mm: memcontrol: Provide a local_lock for per-CPU + memcg_stock + +The interrupts are disabled to ensure CPU-local access to the per-CPU +variable `memcg_stock'. +As the code inside the interrupt disabled section acquires regular +spinlocks, which are converted to 'sleeping' spinlocks on a PREEMPT_RT +kernel, this conflicts with the RT semantics. + +Convert it to a local_lock which allows RT kernels to substitute them with +a real per CPU lock. On non RT kernels this maps to local_irq_save() as +before, but provides also lockdep coverage of the critical region. +No functional change. + +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + mm/memcontrol.c | 31 ++++++++++++++++++------------- + 1 file changed, 18 insertions(+), 13 deletions(-) + +diff --git a/mm/memcontrol.c b/mm/memcontrol.c +index 24091f7a64e2..74a65d87866c 100644 +--- a/mm/memcontrol.c ++++ b/mm/memcontrol.c +@@ -2210,6 +2210,7 @@ void unlock_page_memcg(struct page *page) + EXPORT_SYMBOL(unlock_page_memcg); + + struct memcg_stock_pcp { ++ local_lock_t lock; + struct mem_cgroup *cached; /* this never be root cgroup */ + unsigned int nr_pages; + +@@ -2261,7 +2262,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) + if (nr_pages > MEMCG_CHARGE_BATCH) + return ret; + +- local_irq_save(flags); ++ local_lock_irqsave(&memcg_stock.lock, flags); + + stock = this_cpu_ptr(&memcg_stock); + if (memcg == stock->cached && stock->nr_pages >= nr_pages) { +@@ -2269,7 +2270,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) + ret = true; + } + +- local_irq_restore(flags); ++ local_unlock_irqrestore(&memcg_stock.lock, flags); + + return ret; + } +@@ -2304,14 +2305,14 @@ static void drain_local_stock(struct work_struct *dummy) + * The only protection from memory hotplug vs. drain_stock races is + * that we always operate on local CPU stock here with IRQ disabled + */ +- local_irq_save(flags); ++ local_lock_irqsave(&memcg_stock.lock, flags); + + stock = this_cpu_ptr(&memcg_stock); + drain_obj_stock(stock); + drain_stock(stock); + clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); + +- local_irq_restore(flags); ++ local_unlock_irqrestore(&memcg_stock.lock, flags); + } + + /* +@@ -2323,7 +2324,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) + struct memcg_stock_pcp *stock; + unsigned long flags; + +- local_irq_save(flags); ++ local_lock_irqsave(&memcg_stock.lock, flags); + + stock = this_cpu_ptr(&memcg_stock); + if (stock->cached != memcg) { /* reset if necessary */ +@@ -2336,7 +2337,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) + if (stock->nr_pages > MEMCG_CHARGE_BATCH) + drain_stock(stock); + +- local_irq_restore(flags); ++ local_unlock_irqrestore(&memcg_stock.lock, flags); + } + + /* +@@ -3158,7 +3159,7 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) + unsigned long flags; + bool ret = false; + +- local_irq_save(flags); ++ local_lock_irqsave(&memcg_stock.lock, flags); + + stock = this_cpu_ptr(&memcg_stock); + if (objcg == stock->cached_objcg && stock->nr_bytes >= nr_bytes) { +@@ -3166,7 +3167,7 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) + ret = true; + } + +- local_irq_restore(flags); ++ local_unlock_irqrestore(&memcg_stock.lock, flags); + + return ret; + } +@@ -3225,7 +3226,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) + struct memcg_stock_pcp *stock; + unsigned long flags; + +- local_irq_save(flags); ++ local_lock_irqsave(&memcg_stock.lock, flags); + + stock = this_cpu_ptr(&memcg_stock); + if (stock->cached_objcg != objcg) { /* reset if necessary */ +@@ -3239,7 +3240,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) + if (stock->nr_bytes > PAGE_SIZE) + drain_obj_stock(stock); + +- local_irq_restore(flags); ++ local_unlock_irqrestore(&memcg_stock.lock, flags); + } + + int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size) +@@ -7065,9 +7066,13 @@ static int __init mem_cgroup_init(void) + cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL, + memcg_hotplug_cpu_dead); + +- for_each_possible_cpu(cpu) +- INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work, +- drain_local_stock); ++ for_each_possible_cpu(cpu) { ++ struct memcg_stock_pcp *stock; ++ ++ stock = per_cpu_ptr(&memcg_stock, cpu); ++ INIT_WORK(&stock->work, drain_local_stock); ++ local_lock_init(&stock->lock); ++ } + + for_each_node(node) { + struct mem_cgroup_tree_per_node *rtpn; +-- +2.19.1 + |