From: Vishal Verma <vishal.l.verma@intel.com>
Date: Wed, 30 Aug 2017 19:36:02 -0600
Subject: libnvdimm: fix potential deadlock while clearing errors
Patch-mainline: v4.14-rc1
Git-commit: 0930a750c35be3c2f5aacebc0d20ddeaf727c208
References: FATE#323731
With the ACPI NFIT 'DSM' methods, acpi can be called from IO paths.
Specifically, the DSM to clear media errors is called during writes, so
that we can provide a writes-fix-errors model.
However it is easy to imagine a scenario like:
-> write through the nvdimm driver
-> acpi allocation
-> writeback, causes more IO through the nvdimm driver
-> deadlock
Fix this by using memalloc_noio_{save,restore}, which sets the GFP_NOIO
flag for the current scope when issuing commands/IOs that are expected
to clear errors.
Cc: <linux-acpi@vger.kernel.org>
Cc: <linux-nvdimm@lists.01.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
drivers/nvdimm/bus.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -11,6 +11,7 @@
* General Public License for more details.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/sched/mm.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
#include <linux/module.h>
@@ -231,6 +232,7 @@ long nvdimm_clear_poison(struct device *
struct nd_cmd_clear_error clear_err;
struct nd_cmd_ars_cap ars_cap;
u32 clear_err_unit, mask;
+ unsigned int noio_flag;
int cmd_rc, rc;
if (!nvdimm_bus)
@@ -247,8 +249,10 @@ long nvdimm_clear_poison(struct device *
memset(&ars_cap, 0, sizeof(ars_cap));
ars_cap.address = phys;
ars_cap.length = len;
+ noio_flag = memalloc_noio_save();
rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_ARS_CAP, &ars_cap,
sizeof(ars_cap), &cmd_rc);
+ memalloc_noio_restore(noio_flag);
if (rc < 0)
return rc;
if (cmd_rc < 0)
@@ -263,8 +267,10 @@ long nvdimm_clear_poison(struct device *
memset(&clear_err, 0, sizeof(clear_err));
clear_err.address = phys;
clear_err.length = len;
+ noio_flag = memalloc_noio_save();
rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_CLEAR_ERROR, &clear_err,
sizeof(clear_err), &cmd_rc);
+ memalloc_noio_restore(noio_flag);
if (rc < 0)
return rc;
if (cmd_rc < 0)