From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>, RCU <rcu@vger.kernel.org>,
"Paul E . McKenney" <paulmck@kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Daniel Axtens <dja@axtens.net>,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
Joel Fernandes <joel@joelfernandes.org>,
Peter Zijlstra <peterz@infradead.org>,
Michal Hocko <mhocko@suse.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Theodore Y . Ts'o" <tytso@mit.edu>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Uladzislau Rezki <urezki@gmail.com>,
Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Subject: [PATCH 1/3] kvfree_rcu: Allocate a page for a single argument
Date: Wed, 20 Jan 2021 17:21:46 +0100 [thread overview]
Message-ID: <20210120162148.1973-1-urezki@gmail.com> (raw)
For a single argument we can directly request a page from a caller
context when a "carry page block" is run out of free spots. Instead
of hitting a slow path we can request an extra page by demand and
proceed with a fast path.
A single-argument kvfree_rcu() must be invoked in sleepable contexts,
and that its fallback is the relatively high latency synchronize_rcu().
Single-argument kvfree_rcu() therefore uses GFP_KERNEL|__GFP_RETRY_MAYFAIL
to allow limited sleeping within the memory allocator.
[ paulmck: Add add_ptr_to_bulk_krc_lock header comment per Michal Hocko. ]
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tree.c | 42 ++++++++++++++++++++++++++----------------
1 file changed, 26 insertions(+), 16 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e04e336bee42..2014fb22644d 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3465,37 +3465,50 @@ run_page_cache_worker(struct kfree_rcu_cpu *krcp)
}
}
+// Record ptr in a page managed by krcp, with the pre-krc_this_cpu_lock()
+// state specified by flags. If can_alloc is true, the caller must
+// be schedulable and not be holding any locks or mutexes that might be
+// acquired by the memory allocator or anything that it might invoke.
+// Returns true if ptr was successfully recorded, else the caller must
+// use a fallback.
static inline bool
-kvfree_call_rcu_add_ptr_to_bulk(struct kfree_rcu_cpu *krcp, void *ptr)
+add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp,
+ unsigned long *flags, void *ptr, bool can_alloc)
{
struct kvfree_rcu_bulk_data *bnode;
int idx;
- if (unlikely(!krcp->initialized))
+ *krcp = krc_this_cpu_lock(flags);
+ if (unlikely(!(*krcp)->initialized))
return false;
- lockdep_assert_held(&krcp->lock);
idx = !!is_vmalloc_addr(ptr);
/* Check if a new block is required. */
- if (!krcp->bkvhead[idx] ||
- krcp->bkvhead[idx]->nr_records == KVFREE_BULK_MAX_ENTR) {
- bnode = get_cached_bnode(krcp);
- /* Switch to emergency path. */
+ if (!(*krcp)->bkvhead[idx] ||
+ (*krcp)->bkvhead[idx]->nr_records == KVFREE_BULK_MAX_ENTR) {
+ bnode = get_cached_bnode(*krcp);
+ if (!bnode && can_alloc) {
+ krc_this_cpu_unlock(*krcp, *flags);
+ bnode = (struct kvfree_rcu_bulk_data *)
+ __get_free_page(GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
+ *krcp = krc_this_cpu_lock(flags);
+ }
+
if (!bnode)
return false;
/* Initialize the new block. */
bnode->nr_records = 0;
- bnode->next = krcp->bkvhead[idx];
+ bnode->next = (*krcp)->bkvhead[idx];
/* Attach it to the head. */
- krcp->bkvhead[idx] = bnode;
+ (*krcp)->bkvhead[idx] = bnode;
}
/* Finally insert. */
- krcp->bkvhead[idx]->records
- [krcp->bkvhead[idx]->nr_records++] = ptr;
+ (*krcp)->bkvhead[idx]->records
+ [(*krcp)->bkvhead[idx]->nr_records++] = ptr;
return true;
}
@@ -3533,8 +3546,6 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
ptr = (unsigned long *) func;
}
- krcp = krc_this_cpu_lock(&flags);
-
// Queue the object but don't yet schedule the batch.
if (debug_rcu_head_queue(ptr)) {
// Probable double kfree_rcu(), just leak.
@@ -3542,12 +3553,11 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
__func__, head);
// Mark as success and leave.
- success = true;
- goto unlock_return;
+ return;
}
kasan_record_aux_stack(ptr);
- success = kvfree_call_rcu_add_ptr_to_bulk(krcp, ptr);
+ success = add_ptr_to_bulk_krc_lock(&krcp, &flags, ptr, !head);
if (!success) {
run_page_cache_worker(krcp);
--
2.20.1
next reply other threads:[~2021-01-20 16:26 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 16:21 Uladzislau Rezki (Sony) [this message]
2021-01-20 16:21 ` [PATCH 2/3] kvfree_rcu: Use __GFP_NOMEMALLOC for single-argument kvfree_rcu() Uladzislau Rezki (Sony)
2021-01-28 18:06 ` Uladzislau Rezki
2021-01-20 16:21 ` [PATCH 3/3] kvfree_rcu: use migrate_disable/enable() Uladzislau Rezki (Sony)
2021-01-20 19:45 ` Sebastian Andrzej Siewior
2021-01-20 21:42 ` Paul E. McKenney
2021-01-23 9:31 ` 回复: " Zhang, Qiang
2021-01-24 21:57 ` Uladzislau Rezki
2021-01-25 1:50 ` 回复: " Zhang, Qiang
2021-01-25 2:18 ` Zhang, Qiang
2021-01-25 13:49 ` Uladzislau Rezki
2021-01-26 9:33 ` 回复: " Zhang, Qiang
2021-01-26 13:43 ` Uladzislau Rezki
2021-01-20 18:40 ` [PATCH 1/3] kvfree_rcu: Allocate a page for a single argument Paul E. McKenney
2021-01-20 19:57 ` Sebastian Andrzej Siewior
2021-01-20 21:54 ` Paul E. McKenney
2021-01-21 13:35 ` Uladzislau Rezki
2021-01-21 15:07 ` Paul E. McKenney
2021-01-21 19:17 ` Uladzislau Rezki
2021-01-22 11:17 ` Sebastian Andrzej Siewior
2021-01-22 15:28 ` Paul E. McKenney
2021-01-21 12:38 ` Uladzislau Rezki
2021-01-22 11:34 ` Sebastian Andrzej Siewior
2021-01-22 14:21 ` Uladzislau Rezki
2021-01-25 13:22 ` Michal Hocko
2021-01-25 14:31 ` Uladzislau Rezki
2021-01-25 15:39 ` Michal Hocko
2021-01-25 16:25 ` Uladzislau Rezki
2021-01-28 15:11 ` Uladzislau Rezki
2021-01-28 15:17 ` Michal Hocko
2021-01-28 15:30 ` Uladzislau Rezki
2021-01-28 18:02 ` Uladzislau Rezki
[not found] ` <YBPNvbJLg56XU8co@dhcp22.suse.cz>
2021-01-29 16:35 ` Uladzislau Rezki
2021-02-01 11:47 ` Michal Hocko
2021-02-01 14:44 ` Uladzislau Rezki
2021-02-03 19:37 ` Paul E. McKenney
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