linux-kernel - [PATCH v2 0/3] ARS rescanning triggered by latent errors or userspace

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Date:	Wed, 20 Jul 2016 19:50:47 -0600
From:	Vishal Verma <vishal.l.verma@...el.com>
To:	<linux-nvdimm@...ts.01.org>
Cc:	Dan Williams <dan.j.williams@...el.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Tony Luck <tony.luck@...el.com>,
	<linux-kernel@...r.kernel.org>, linux-acpi@...r.kernel.org,
	Vishal Verma <vishal.l.verma@...el.com>
Subject: [PATCH v2 0/3] ARS rescanning triggered by latent errors or userspace

Changes in v2:
- Rework the ars_done flag in nfit_spa to be ars_required, and reuse it for
  rescanning (Dan)
- Rename the ars_rescan attribute to simply 'scrub', and move into the nfit
  group since only nfit buses have this capability (Dan)
- Make the scrub attribute RW, and on reads return the number of times a
  scrub has happened since driver load. This prompted some additional
  refactoring, notably the new helpers acpi_nfit_desc_alloc_register, and
  to_nvdimm_bus_dev. These are all in patch 2. (Dan)
- Remove some redundant list_empty checks in patch 3 (Dan)
- If the acpi_descs lists is not empty at driver unload time, WARN() (Dan)

This series adds on-demand ARS scanning on both, discovery of
latent media errors, and a sysfs trigger from userspace.

The rescanning part is easy to test using the nfit_test framework
- create a namespace (this will by default have bad sectors in
the middle), clear the bad sectors by writing to them, trigger
the rescan through sysfs, and the bad sectors will reappear in
/sys/block/<pmemX>/badblocks.

For the mce handling, I've tested the notifier chain callback
being called with a mock struct mce (called via another sysfs
trigger - this isn't included in the patch obviously), which
has the address field set to a known address in a SPA range,
and the status field with the MCACOD flag set.

What I haven't easily been able to test is the same callback
path with a 'real world' mce, being called as part of the
x86_mce_decoder_chain notifier. I'd therefore appreciate a
closer look at the initial filtering done in nfit_handle_mce
(patch 3/3) from Tony or anyone more familiar with mce handling.

The series is based on v4.7-rc7, and a tree is available at
https://git.kernel.org/cgit/linux/kernel/git/vishal/nvdimm.git/log/?h=ars-ondemand



Vishal Verma (3):
  pmem: clarify a debug print in pmem_clear_poison
  nfit, libnvdimm: allow an ARS scrub to be triggered on demand
  nfit: do an ARS scrub on hitting a latent media error

 drivers/acpi/nfit.c              | 214 +++++++++++++++++++++++++++++++++++----
 drivers/acpi/nfit.h              |   5 +-
 drivers/nvdimm/core.c            |   7 ++
 drivers/nvdimm/pmem.c            |   2 +-
 include/linux/libnvdimm.h        |   1 +
 tools/testing/nvdimm/test/nfit.c |  16 +++
 6 files changed, 224 insertions(+), 21 deletions(-)

-- 
2.7.4