From 52e73eb2872c9af6f382b2b22954ca8214397a4e Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 27 Oct 2016 17:04:05 -0700 Subject: [PATCH] device-dax: fix percpu_ref_exit ordering We need to wait until the percpu_ref is released before exit. Otherwise, we sometimes lose the race and trigger this new warning that was added in v4.9 (commit a67823c1ed10 "percpu-refcount: init ->confirm_switch member properly"): WARNING: CPU: 0 PID: 3629 at lib/percpu-refcount.c:107 percpu_ref_exit+0x51/0x60 [..] Call Trace: [] dump_stack+0x85/0xc2 [] __warn+0xcb/0xf0 [] warn_slowpath_null+0x1d/0x20 [] percpu_ref_exit+0x51/0x60 [] dax_pmem_percpu_exit+0x1a/0x50 [dax_pmem] [] devm_action_release+0xf/0x20 Cc: Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory") Signed-off-by: Dan Williams --- drivers/dax/pmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c index 9630d8837ba9..4a15fa5df98b 100644 --- a/drivers/dax/pmem.c +++ b/drivers/dax/pmem.c @@ -44,7 +44,6 @@ static void dax_pmem_percpu_exit(void *data) dev_dbg(dax_pmem->dev, "%s\n", __func__); percpu_ref_exit(ref); - wait_for_completion(&dax_pmem->cmp); } static void dax_pmem_percpu_kill(void *data) @@ -54,6 +53,7 @@ static void dax_pmem_percpu_kill(void *data) dev_dbg(dax_pmem->dev, "%s\n", __func__); percpu_ref_kill(ref); + wait_for_completion(&dax_pmem->cmp); } static int dax_pmem_probe(struct device *dev)