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authorIngo Molnar <mingo@kernel.org>2021-02-12 14:50:09 +0300
committerIngo Molnar <mingo@kernel.org>2021-02-12 14:56:55 +0300
commit85e853c5ec8486117182baab10c98b321daa6d47 (patch)
tree404551f51bc88ba9f4cc64431e2633493a971842 /lib
parentdcc0b49040c70ad827a7f3d58a21b01fdb14e749 (diff)
parent0d2460ba61841e5c2e64e77f7a84d3fc69cfe899 (diff)
downloadlinux-85e853c5ec8486117182baab10c98b321daa6d47.tar.xz
Merge branch 'for-mingo-rcu' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU updates from Paul E. McKenney: - Documentation updates. - Miscellaneous fixes. - kfree_rcu() updates: Addition of mem_dump_obj() to provide allocator return addresses to more easily locate bugs. This has a couple of RCU-related commits, but is mostly MM. Was pulled in with akpm's agreement. - Per-callback-batch tracking of numbers of callbacks, which enables better debugging information and smarter reactions to large numbers of callbacks. - The first round of changes to allow CPUs to be runtime switched from and to callback-offloaded state. - CONFIG_PREEMPT_RT-related changes. - RCU CPU stall warning updates. - Addition of polling grace-period APIs for SRCU. - Torture-test and torture-test scripting updates, including a "torture everything" script that runs rcutorture, locktorture, scftorture, rcuscale, and refscale. Plus does an allmodconfig build. Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/percpu-refcount.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index e59eda07305e..a1071cdefb5a 100644
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -5,6 +5,7 @@
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/slab.h>
+#include <linux/mm.h>
#include <linux/percpu-refcount.h>
/*
@@ -168,6 +169,7 @@ static void percpu_ref_switch_to_atomic_rcu(struct rcu_head *rcu)
struct percpu_ref_data, rcu);
struct percpu_ref *ref = data->ref;
unsigned long __percpu *percpu_count = percpu_count_ptr(ref);
+ static atomic_t underflows;
unsigned long count = 0;
int cpu;
@@ -191,9 +193,13 @@ static void percpu_ref_switch_to_atomic_rcu(struct rcu_head *rcu)
*/
atomic_long_add((long)count - PERCPU_COUNT_BIAS, &data->count);
- WARN_ONCE(atomic_long_read(&data->count) <= 0,
- "percpu ref (%ps) <= 0 (%ld) after switching to atomic",
- data->release, atomic_long_read(&data->count));
+ if (WARN_ONCE(atomic_long_read(&data->count) <= 0,
+ "percpu ref (%ps) <= 0 (%ld) after switching to atomic",
+ data->release, atomic_long_read(&data->count)) &&
+ atomic_inc_return(&underflows) < 4) {
+ pr_err("%s(): percpu_ref underflow", __func__);
+ mem_dump_obj(data);
+ }
/* @ref is viewed as dead on all CPUs, send out switch confirmation */
percpu_ref_call_confirm_rcu(rcu);