From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E . McKenney" <paulmck@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Matthew Wilcox <willy@infradead.org>,
linux-fsdevel@vger.kernel.org
Subject: [PATCH 2/8] radix-tree: Use local_lock for protection
Date: Tue, 19 May 2020 22:19:06 +0200 [thread overview]
Message-ID: <20200519201912.1564477-3-bigeasy@linutronix.de> (raw)
In-Reply-To: <20200519201912.1564477-1-bigeasy@linutronix.de>
The radix-tree and idr preload mechanisms use preempt_disable() to protect
the complete operation between xxx_preload() and xxx_preload_end().
As the code inside the preempt disabled section acquires regular spinlocks,
which are converted to 'sleeping' spinlocks on a PREEMPT_RT kernel and
eventually calls into a memory allocator, 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 preempt_disable() as
before, but provides also lockdep coverage of the critical region.
No functional change.
Cc: Matthew Wilcox <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/idr.h | 5 +----
include/linux/radix-tree.h | 6 +-----
lib/radix-tree.c | 25 +++++++++++++++++++------
3 files changed, 21 insertions(+), 15 deletions(-)
diff --git a/include/linux/idr.h b/include/linux/idr.h
index ac6e946b6767b..839da8f2f6f13 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -169,10 +169,7 @@ static inline bool idr_is_empty(const struct idr *idr)
* Each idr_preload() should be matched with an invocation of this
* function. See idr_preload() for details.
*/
-static inline void idr_preload_end(void)
-{
- preempt_enable();
-}
+void idr_preload_end(void);
/**
* idr_for_each_entry() - Iterate over an IDR's elements of a given type.
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 63e62372443a5..040b1fd0ab940 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -226,6 +226,7 @@ unsigned int radix_tree_gang_lookup(const struct radix_tree_root *,
unsigned int max_items);
int radix_tree_preload(gfp_t gfp_mask);
int radix_tree_maybe_preload(gfp_t gfp_mask);
+void radix_tree_preload_end(void);
void radix_tree_init(void);
void *radix_tree_tag_set(struct radix_tree_root *,
unsigned long index, unsigned int tag);
@@ -243,11 +244,6 @@ unsigned int radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *,
unsigned int max_items, unsigned int tag);
int radix_tree_tagged(const struct radix_tree_root *, unsigned int tag);
-static inline void radix_tree_preload_end(void)
-{
- preempt_enable();
-}
-
void __rcu **idr_get_free(struct radix_tree_root *root,
struct radix_tree_iter *iter, gfp_t gfp,
unsigned long max);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 2ee6ae3b0ade0..8a44f7b85dfdc 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -20,6 +20,7 @@
#include <linux/kernel.h>
#include <linux/kmemleak.h>
#include <linux/percpu.h>
+#include <linux/locallock.h>
#include <linux/preempt.h> /* in_interrupt() */
#include <linux/radix-tree.h>
#include <linux/rcupdate.h>
@@ -27,7 +28,6 @@
#include <linux/string.h>
#include <linux/xarray.h>
-
/*
* Radix tree node cache.
*/
@@ -64,6 +64,7 @@ struct radix_tree_preload {
struct radix_tree_node *nodes;
};
static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
+static DEFINE_LOCAL_LOCK(radix_tree_preloads_lock);
static inline struct radix_tree_node *entry_to_node(void *ptr)
{
@@ -332,14 +333,14 @@ static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)
*/
gfp_mask &= ~__GFP_ACCOUNT;
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
rtp = this_cpu_ptr(&radix_tree_preloads);
while (rtp->nr < nr) {
- preempt_enable();
+ local_unlock(radix_tree_preloads_lock);
node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
if (node == NULL)
goto out;
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
rtp = this_cpu_ptr(&radix_tree_preloads);
if (rtp->nr < nr) {
node->parent = rtp->nodes;
@@ -381,11 +382,17 @@ int radix_tree_maybe_preload(gfp_t gfp_mask)
if (gfpflags_allow_blocking(gfp_mask))
return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
/* Preloading doesn't help anything with this gfp mask, skip it */
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
return 0;
}
EXPORT_SYMBOL(radix_tree_maybe_preload);
+void radix_tree_preload_end(void)
+{
+ local_unlock(radix_tree_preloads_lock);
+}
+EXPORT_SYMBOL(radix_tree_preload_end);
+
static unsigned radix_tree_load_root(const struct radix_tree_root *root,
struct radix_tree_node **nodep, unsigned long *maxindex)
{
@@ -1470,10 +1477,16 @@ EXPORT_SYMBOL(radix_tree_tagged);
void idr_preload(gfp_t gfp_mask)
{
if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE))
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
}
EXPORT_SYMBOL(idr_preload);
+void idr_preload_end(void)
+{
+ local_unlock(radix_tree_preloads_lock);
+}
+EXPORT_SYMBOL(idr_preload_end);
+
void __rcu **idr_get_free(struct radix_tree_root *root,
struct radix_tree_iter *iter, gfp_t gfp,
unsigned long max)
--
2.26.2
next prev parent reply other threads:[~2020-05-19 20:20 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 20:19 [PATCH 0/8] Introduce local_lock() Sebastian Andrzej Siewior
2020-05-19 20:19 ` [PATCH 1/8] locking: " Sebastian Andrzej Siewior
2020-05-20 12:04 ` Peter Zijlstra
2020-05-22 11:05 ` Sebastian Andrzej Siewior
2020-05-22 13:01 ` Peter Zijlstra
2020-05-19 20:19 ` Sebastian Andrzej Siewior [this message]
2020-05-19 20:45 ` [PATCH 2/8] radix-tree: Use local_lock for protection Matthew Wilcox
2020-05-19 20:54 ` Steven Rostedt
2020-05-20 2:05 ` Matthew Wilcox
2020-05-20 10:13 ` Sebastian Andrzej Siewior
2020-05-20 10:21 ` Peter Zijlstra
2020-05-20 12:28 ` Thomas Gleixner
2020-05-19 20:19 ` [PATCH 3/8] srcu: Use local_lock() for per-CPU struct srcu_data access Sebastian Andrzej Siewior
2020-05-20 10:24 ` Peter Zijlstra
2020-05-20 12:06 ` Sebastian Andrzej Siewior
2020-05-20 13:27 ` Peter Zijlstra
2020-05-20 17:42 ` Joel Fernandes
2020-05-20 18:28 ` Sebastian Andrzej Siewior
2020-05-20 18:35 ` Peter Zijlstra
2020-05-20 18:44 ` Joel Fernandes
2020-05-20 18:50 ` Uladzislau Rezki
2020-05-20 18:59 ` Joel Fernandes
2020-05-20 18:43 ` Paul E. McKenney
2020-05-22 15:12 ` Sebastian Andrzej Siewior
2020-05-22 17:39 ` Paul E. McKenney
2020-05-23 15:08 ` Sebastian Andrzej Siewior
2020-05-23 16:59 ` Paul E. McKenney
2020-05-24 19:03 ` Sebastian Andrzej Siewior
2020-05-25 3:27 ` Paul E. McKenney
2020-05-26 13:41 ` [PATCH] srcu: Avoid local_irq_save() before acquiring spinlock_t Sebastian Andrzej Siewior
2020-05-26 16:16 ` Paul E. McKenney
2020-05-26 16:31 ` Sebastian Andrzej Siewior
2020-05-19 20:19 ` [PATCH 4/8] mm/swap: Use local_lock for protection Sebastian Andrzej Siewior
2020-05-19 23:58 ` Andrew Morton
2020-05-20 2:17 ` Matthew Wilcox
2020-05-20 10:53 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 5/8] squashfs: make use of local lock in multi_cpu decompressor Sebastian Andrzej Siewior
2020-05-20 10:56 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 6/8] connector/cn_proc: Protect send_msg() with a local lock Sebastian Andrzej Siewior
2020-05-20 11:03 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 7/8] zram: Use local lock to protect per-CPU data Sebastian Andrzej Siewior
2020-05-20 11:07 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 8/8] mm/zswap: " Sebastian Andrzej Siewior
2020-05-19 21:46 ` Song Bao Hua
2020-05-20 10:26 ` Sebastian Andrzej Siewior
2020-05-20 11:13 ` Song Bao Hua
2020-05-20 11:57 ` Sebastian Andrzej Siewior
2020-05-20 12:01 ` Song Bao Hua
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