libnvdimm: fix potential deadlock while clearing errors (0930a750) · Commits · 戴 / test

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>

drivers/nvdimm/bus.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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>
		@@ -234,6 +235,7 @@ 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)
		@@ -250,8 +252,10 @@ 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)
		@@ -266,8 +270,10 @@ 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)

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