Even after we fix the use of a non raw lock in free_ioctx_users()
we still get another follow on splat. This one looks as follows:
BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:905
in_atomic(): 1, irqs_disabled(): 0, pid: 14, name: rcuc/0
Preemption disabled at:[<ffffffff810ada55>] rcu_cpu_kthread+0x295/0x6f0
CPU: 0 PID: 14 Comm: rcuc/0 Not tainted 3.14.31-rt28-WR7.0.0.0_ovp+ #5
Hardware name: Intel Corporation S2600CP/S2600CP, BIOS SE5C600.86B.02.01.0002.082220131453 08/22/2013
000000000000c3c0 ffff880fb393fd28 ffffffff819ffe6b 0000000000000000
ffff880fb393fd40 ffffffff8107b6cb ffff880ffe60c3c0 ffff880fb393fd58
ffffffff81a077c0 ffff880ffe60c3c0 ffff880fb393fd98 ffffffff81066f05
Call Trace:
[<ffffffff819ffe6b>] dump_stack+0x4e/0x7a
[<ffffffff8107b6cb>] __might_sleep+0xdb/0x150
[<ffffffff81a077c0>] rt_spin_lock+0x20/0x50
[<ffffffff81066f05>] queue_work_on+0x65/0x110
[<ffffffff811c714b>] free_ioctx_reqs+0x5b/0x60
[<ffffffff813ff06b>] percpu_ref_kill_rcu+0x11b/0x120
[<ffffffff810ada55>] rcu_cpu_kthread+0x295/0x6f0
[<ffffffff81076c7d>] smpboot_thread_fn+0x17d/0x2b0
[<ffffffff81a05220>] ? schedule+0x30/0xa0
[<ffffffff81076b00>] ? SyS_setgroups+0x170/0x170
[<ffffffff8106f3f4>] kthread+0xc4/0xe0
[<ffffffff8106f330>] ? flush_kthread_worker+0x90/0x90
[<ffffffff81a088ec>] ret_from_fork+0x7c/0xb0
[<ffffffff8106f330>] ? flush_kthread_worker+0x90/0x90
This is caused by schedule_work() being called from free_ioctx_reqs(),
and the underlying reason is the same, that this release fcn...
* Note that @release must not sleep - it may potentially be called from RCU
* callback context by percpu_ref_kill().
and the sleep is spin_lock_irqsave(&lv->lock, lv->flags) inside
queue_work_on().
We can fix this up by using the callback version percpu_ref_kill
and register the callback to do the schedule_work(). With this
in place a reboot doesn't splat during aio garbage collection.
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
fs/aio.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/aio.c b/fs/aio.c
index d806f7223822..db1ce6d73cc7 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -524,6 +524,11 @@ static void free_ioctx_reqs(struct percpu_ref *ref)
/* At this point we know that there are no any in-flight requests */
if (ctx->requests_done)
complete(ctx->requests_done);
+}
+
+static void free_ioctx_reqs_callback(struct percpu_ref *ref)
+{
+ struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
INIT_WORK(&ctx->free_work, free_ioctx);
schedule_work(&ctx->free_work);
@@ -558,7 +563,7 @@ static void free_ioctx_users(struct percpu_ref *ref)
spin_unlock_irq(&ctx->ctx_lock);
#endif
- percpu_ref_kill(&ctx->reqs);
+ percpu_ref_kill_and_confirm(&ctx->reqs, free_ioctx_reqs_callback);
percpu_ref_put(&ctx->reqs);
}
--
2.1.0
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