All of lore.kernel.org
 help / color / mirror / Atom feed
From: Dan Williams <dan.j.williams@intel.com>
To: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: [PATCH] device-dax: fix percpu_ref_exit ordering
Date: Thu, 27 Oct 2016 17:18:02 -0700	[thread overview]
Message-ID: <147761388212.10087.4433175969243569236.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)

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:
  [<ffffffff814bf093>] dump_stack+0x85/0xc2
  [<ffffffff810b15db>] __warn+0xcb/0xf0
  [<ffffffff810b170d>] warn_slowpath_null+0x1d/0x20
  [<ffffffff814d70c1>] percpu_ref_exit+0x51/0x60
  [<ffffffffa005706a>] dax_pmem_percpu_exit+0x1a/0x50 [dax_pmem]
  [<ffffffff81615f1f>] devm_action_release+0xf/0x20

Cc: <stable@vger.kernel.org>
Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 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)

_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm

WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com>
To: linux-nvdimm@ml01.01.org
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: [PATCH] device-dax: fix percpu_ref_exit ordering
Date: Thu, 27 Oct 2016 17:18:02 -0700	[thread overview]
Message-ID: <147761388212.10087.4433175969243569236.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)

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:
  [<ffffffff814bf093>] dump_stack+0x85/0xc2
  [<ffffffff810b15db>] __warn+0xcb/0xf0
  [<ffffffff810b170d>] warn_slowpath_null+0x1d/0x20
  [<ffffffff814d70c1>] percpu_ref_exit+0x51/0x60
  [<ffffffffa005706a>] dax_pmem_percpu_exit+0x1a/0x50 [dax_pmem]
  [<ffffffff81615f1f>] devm_action_release+0xf/0x20

Cc: <stable@vger.kernel.org>
Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 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)

WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com>
To: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: [PATCH] device-dax: fix percpu_ref_exit ordering
Date: Thu, 27 Oct 2016 17:18:02 -0700	[thread overview]
Message-ID: <147761388212.10087.4433175969243569236.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)

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:
  [<ffffffff814bf093>] dump_stack+0x85/0xc2
  [<ffffffff810b15db>] __warn+0xcb/0xf0
  [<ffffffff810b170d>] warn_slowpath_null+0x1d/0x20
  [<ffffffff814d70c1>] percpu_ref_exit+0x51/0x60
  [<ffffffffa005706a>] dax_pmem_percpu_exit+0x1a/0x50 [dax_pmem]
  [<ffffffff81615f1f>] devm_action_release+0xf/0x20

Cc: <stable@vger.kernel.org>
Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 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)


             reply	other threads:[~2016-10-28  0:21 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-28  0:18 Dan Williams [this message]
2016-10-28  0:18 ` [PATCH] device-dax: fix percpu_ref_exit ordering Dan Williams
2016-10-28  0:18 ` Dan Williams

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=147761388212.10087.4433175969243569236.stgit@dwillia2-desk3.amr.corp.intel.com \
    --to=dan.j.williams@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nvdimm@lists.01.org \
    --cc=stable@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.