From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>, linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Paul E . McKenney" <paulmck@kernel.org>,
"Theodore Y . Ts'o" <tytso@mit.edu>,
Matthew Wilcox <willy@infradead.org>,
Joel Fernandes <joel@joelfernandes.org>,
RCU <rcu@vger.kernel.org>, Uladzislau Rezki <urezki@gmail.com>,
Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Subject: [PATCH v2 04/16] rcu/tree: Make debug_objects logic independent of rcu_head
Date: Mon, 25 May 2020 23:47:48 +0200 [thread overview]
Message-ID: <20200525214800.93072-5-urezki@gmail.com> (raw)
In-Reply-To: <20200525214800.93072-1-urezki@gmail.com>
From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
kfree_rcu()'s debug_objects logic uses the address of the object's
embedded rcu_head to queue/unqueue. Instead of this, make use of the
object's address itself as preparation for future headless kfree_rcu()
support.
Reviewed-by: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
kernel/rcu/tree.c | 29 +++++++++++++----------------
1 file changed, 13 insertions(+), 16 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index ae21e1bddd3e..776ccf858154 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2836,13 +2836,11 @@ EXPORT_SYMBOL_GPL(call_rcu);
* @nr_records: Number of active pointers in the array
* @records: Array of the kfree_rcu() pointers
* @next: Next bulk object in the block chain
- * @head_free_debug: For debug, when CONFIG_DEBUG_OBJECTS_RCU_HEAD is set
*/
struct kfree_rcu_bulk_data {
unsigned long nr_records;
void *records[KFREE_BULK_MAX_ENTR];
struct kfree_rcu_bulk_data *next;
- struct rcu_head *head_free_debug;
};
/**
@@ -2892,11 +2890,13 @@ struct kfree_rcu_cpu {
static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc);
static __always_inline void
-debug_rcu_head_unqueue_bulk(struct rcu_head *head)
+debug_rcu_bhead_unqueue(struct kfree_rcu_bulk_data *bhead)
{
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
- for (; head; head = head->next)
- debug_rcu_head_unqueue(head);
+ int i;
+
+ for (i = 0; i < bhead->nr_records; i++)
+ debug_rcu_head_unqueue((struct rcu_head *)(bhead->records[i]));
#endif
}
@@ -2926,7 +2926,7 @@ static void kfree_rcu_work(struct work_struct *work)
for (; bhead; bhead = bnext) {
bnext = bhead->next;
- debug_rcu_head_unqueue_bulk(bhead->head_free_debug);
+ debug_rcu_bhead_unqueue(bhead);
rcu_lock_acquire(&rcu_callback_map);
trace_rcu_invoke_kfree_bulk_callback(rcu_state.name,
@@ -2948,14 +2948,15 @@ static void kfree_rcu_work(struct work_struct *work)
*/
for (; head; head = next) {
unsigned long offset = (unsigned long)head->func;
+ void *ptr = (void *)head - offset;
next = head->next;
- debug_rcu_head_unqueue(head);
+ debug_rcu_head_unqueue((struct rcu_head *)ptr);
rcu_lock_acquire(&rcu_callback_map);
trace_rcu_invoke_kfree_callback(rcu_state.name, head, offset);
if (!WARN_ON_ONCE(!__is_kfree_rcu_offset(offset)))
- kfree((void *)head - offset);
+ kfree(ptr);
rcu_lock_release(&rcu_callback_map);
cond_resched_tasks_rcu_qs();
@@ -3094,18 +3095,11 @@ kfree_call_rcu_add_ptr_to_bulk(struct kfree_rcu_cpu *krcp,
/* Initialize the new block. */
bnode->nr_records = 0;
bnode->next = krcp->bhead;
- bnode->head_free_debug = NULL;
/* Attach it to the head. */
krcp->bhead = bnode;
}
-#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
- head->func = func;
- head->next = krcp->bhead->head_free_debug;
- krcp->bhead->head_free_debug = head;
-#endif
-
/* Finally insert. */
krcp->bhead->records[krcp->bhead->nr_records++] =
(void *) head - (unsigned long) func;
@@ -3129,14 +3123,17 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
{
unsigned long flags;
struct kfree_rcu_cpu *krcp;
+ void *ptr;
local_irq_save(flags); // For safely calling this_cpu_ptr().
krcp = this_cpu_ptr(&krc);
if (krcp->initialized)
raw_spin_lock(&krcp->lock);
+ ptr = (void *)head - (unsigned long)func;
+
// Queue the object but don't yet schedule the batch.
- if (debug_rcu_head_queue(head)) {
+ if (debug_rcu_head_queue(ptr)) {
// Probable double kfree_rcu(), just leak.
WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
__func__, head);
--
2.20.1
next prev parent reply other threads:[~2020-05-25 21:49 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 21:47 [PATCH v2 00/16] Introduce kvfree_rcu(1 or 2 arguments) Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 01/16] rcu/tree: Keep kfree_rcu() awake during lock contention Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 02/16] rcu/tree: Skip entry into the page allocator for PREEMPT_RT Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 03/16] rcu/tree: Repeat the monitor if any free channel is busy Uladzislau Rezki (Sony)
2020-05-25 21:47 ` Uladzislau Rezki (Sony) [this message]
2020-05-25 21:47 ` [PATCH v2 05/16] rcu/tree: Simplify KFREE_BULK_MAX_ENTR macro Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 06/16] rcu/tree: Move kfree_rcu_cpu locking/unlocking to separate functions Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 07/16] rcu/tree: Use static initializer for krc.lock Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 08/16] rcu/tree: cache specified number of objects Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 09/16] rcu/tree: Maintain separate array for vmalloc ptrs Uladzislau Rezki (Sony)
2020-06-17 23:46 ` Paul E. McKenney
2020-06-18 0:52 ` Matthew Wilcox
2020-06-18 3:18 ` Paul E. McKenney
2020-06-18 17:35 ` Uladzislau Rezki
2020-06-18 17:57 ` Paul E. McKenney
2020-06-18 18:34 ` Uladzislau Rezki
2020-06-18 19:03 ` Paul E. McKenney
2020-06-18 20:35 ` Uladzislau Rezki
2020-06-18 20:38 ` Matthew Wilcox
2020-06-18 21:17 ` Uladzislau Rezki
2020-06-18 21:34 ` Paul E. McKenney
2020-06-19 15:46 ` Uladzislau Rezki
2020-06-19 16:25 ` Paul E. McKenney
2020-06-22 19:04 ` Uladzislau Rezki
2020-06-22 19:53 ` Paul E. McKenney
2020-06-30 17:46 ` Uladzislau Rezki
2020-06-18 17:30 ` Uladzislau Rezki
2020-06-18 17:35 ` Matthew Wilcox
2020-06-18 20:03 ` Uladzislau Rezki
2020-06-18 17:25 ` Uladzislau Rezki
2020-06-18 17:32 ` Paul E. McKenney
2020-06-18 17:56 ` Uladzislau Rezki
2020-06-18 18:15 ` Matthew Wilcox
2020-06-18 18:23 ` Uladzislau Rezki
2020-06-18 18:37 ` Matthew Wilcox
2020-06-18 18:48 ` Uladzislau Rezki
2020-05-25 21:47 ` [PATCH v2 10/16] rcu/tiny: support vmalloc in tiny-RCU Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 11/16] rcu: Rename *_kfree_callback/*_kfree_rcu_offset/kfree_call_* Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 12/16] mm/list_lru.c: Rename kvfree_rcu() to local variant Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 13/16] rcu: Introduce 2 arg kvfree_rcu() interface Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 14/16] rcu: Support reclaim for head-less object Uladzislau Rezki (Sony)
2020-05-25 21:47 ` [PATCH v2 15/16] rcu: Introduce single argument kvfree_rcu() interface Uladzislau Rezki (Sony)
2020-05-25 21:48 ` [PATCH v2 16/16] lib/test_vmalloc.c: Add test cases for kvfree_rcu() Uladzislau Rezki (Sony)
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