| Message ID | 20170717235655.26424-7-vishal.l.verma@intel.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Mon, Jul 17, 2017 at 4:56 PM, Vishal Verma <vishal.l.verma@intel.com> wrote: > 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> Looks good to me. Please move this up in the series before we start calling nvdimm_clear_poison() in the btt I/O path so there's no bisection point where this deadlock comes back. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c index e9361bf..56c81ac 100644 --- 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 *dev, phys_addr_t phys, 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 *dev, phys_addr_t phys, 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 *dev, phys_addr_t phys, 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)
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> --- drivers/nvdimm/bus.c | 6 ++++++ 1 file changed, 6 insertions(+)