linux-stable.git/drivers/nvdimm, branch v5.3

libnvdimm/pfn: Fix namespace creation on misaligned addresses

2019-08-28T17:33:13+00:00

Yi reported[1] that after commit a3619190d62e ("libnvdimm/pfn: stop
padding pmem namespaces to section alignment"), it was no longer
possible to create a device dax namespace with a 1G alignment.  The
reason was that the pmem region was not itself 1G-aligned.  The code
happily skips past the first 512M, but fails to account for a now
misaligned end offset (since space was allocated starting at that
misaligned address, and extending for size GBs).  Reintroduce
end_trunc, so that the code correctly handles the misaligned end
address.  This results in the same behavior as before the introduction
of the offending commit.

[1] https://lists.01.org/pipermail/linux-nvdimm/2019-July/022813.html

Fixes: a3619190d62e ("libnvdimm/pfn: stop padding pmem namespaces ...")
Reported-and-tested-by: Yi Zhang 
Signed-off-by: Jeff Moyer 
Link: https://lore.kernel.org/r/x49ftll8f39.fsf@segfault.boston.devel.redhat.com
Signed-off-by: Dan Williams

Merge tag 'libnvdimm-fixes-5.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

2019-07-27T15:25:51+00:00

Pull libnvdimm fixes from Dan Williams:
"A collection of locking and async operations fixes for v5.3-rc2. These
had been soaking in a branch targeting the merge window, but missed
due to a regression hunt. This fixed up version has otherwise been in
-next this past week with no reported issues.

In order to gain confidence in the locking changes the pull also
includes a debug / instrumentation patch to enable lockdep coverage
for libnvdimm subsystem operations that depend on the device_lock for
exclusion. As mentioned in the changelog it is a hack, but it works
and documents the locking expectations of the sub-system in a way that
others can use lockdep to verify. The driver core touches got an ack
from Greg.

Summary:

- Fix duplicate device_unregister() calls (multiple threads competing
to do unregister work when scheduling device removal from a sysfs
attribute of the self-same device).

- Fix badblocks registration order bug. Ensure region badblocks are
initialized in advance of namespace registration.

- Fix a deadlock between the bus lock and probe operations.

- Export device-core infrastructure to coordinate async operations
via the device ->dead state.

- Add device-core infrastructure to validate device_lock() usage with
lockdep"

* tag 'libnvdimm-fixes-5.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
driver-core, libnvdimm: Let device subsystems add local lockdep coverage
libnvdimm/bus: Fix wait_nvdimm_bus_probe_idle() ABBA deadlock
libnvdimm/bus: Stop holding nvdimm_bus_list_mutex over __nd_ioctl()
libnvdimm/bus: Prepare the nd_ioctl() path to be re-entrant
libnvdimm/region: Register badblocks before namespaces
libnvdimm/bus: Prevent duplicate device_unregister() calls
drivers/base: Introduce kill_device()

Merge branch 'akpm' (patches from Andrew)

2019-07-19T16:45:58+00:00

Merge yet more updates from Andrew Morton:
 "The rest of MM and a kernel-wide procfs cleanup.

  Summary of the more significant patches:

   - Patch series "mm/memory_hotplug: Factor out memory block
     devicehandling", v3. David Hildenbrand.

     Some spring-cleaning of the memory hotplug code, notably in
     drivers/base/memory.c

   - "mm: thp: fix false negative of shmem vma's THP eligibility". Yang
     Shi.

     Fix /proc/pid/smaps output for THP pages used in shmem.

   - "resource: fix locking in find_next_iomem_res()" + 1. Nadav Amit.

     Bugfix and speedup for kernel/resource.c

   - Patch series "mm: Further memory block device cleanups", David
     Hildenbrand.

     More spring-cleaning of the memory hotplug code.

   - Patch series "mm: Sub-section memory hotplug support". Dan
     Williams.

     Generalise the memory hotplug code so that pmem can use it more
     completely. Then remove the hacks from the libnvdimm code which
     were there to work around the memory-hotplug code's constraints.

   - "proc/sysctl: add shared variables for range check", Matteo Croce.

     We have about 250 instances of

          int zero;
          ...
                  .extra1 = &zero,

     in the tree. This is a tree-wide sweep to make all those private
     "zero"s and "one"s use global variables.

     Alas, it isn't practical to make those two global integers const"

* emailed patches from Andrew Morton : (38 commits)
  proc/sysctl: add shared variables for range check
  mm: migrate: remove unused mode argument
  mm/sparsemem: cleanup 'section number' data types
  libnvdimm/pfn: stop padding pmem namespaces to section alignment
  libnvdimm/pfn: fix fsdax-mode namespace info-block zero-fields
  mm/devm_memremap_pages: enable sub-section remap
  mm: document ZONE_DEVICE memory-model implications
  mm/sparsemem: support sub-section hotplug
  mm/sparsemem: prepare for sub-section ranges
  mm: kill is_dev_zone() helper
  mm/hotplug: kill is_dev_zone() usage in __remove_pages()
  mm/sparsemem: convert kmalloc_section_memmap() to populate_section_memmap()
  mm/hotplug: prepare shrink_{zone, pgdat}_span for sub-section removal
  mm/sparsemem: add helpers track active portions of a section at boot
  mm/sparsemem: introduce a SECTION_IS_EARLY flag
  mm/sparsemem: introduce struct mem_section_usage
  drivers/base/memory.c: get rid of find_memory_block_hinted()
  mm/memory_hotplug: move and simplify walk_memory_blocks()
  mm/memory_hotplug: rename walk_memory_range() and pass start+size instead of pfns
  mm: make register_mem_sect_under_node() static
  ...

libnvdimm/pfn: stop padding pmem namespaces to section alignment

2019-07-19T00:08:07+00:00

Now that the mm core supports section-unaligned hotplug of ZONE_DEVICE
memory, we no longer need to add padding at pfn/dax device creation
time.  The kernel will still honor padding established by older kernels.

Link: http://lkml.kernel.org/r/156092356588.979959.6793371748950931916.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams 
Reported-by: Jeff Moyer 
Tested-by: Aneesh Kumar K.V 	[ppc64]
Cc: David Hildenbrand 
Cc: Jane Chu 
Cc: Jérôme Glisse 
Cc: Jonathan Corbet 
Cc: Logan Gunthorpe 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Oscar Salvador 
Cc: Pavel Tatashin 
Cc: Toshi Kani 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Cc: Jason Gunthorpe 
Cc: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

libnvdimm/pfn: fix fsdax-mode namespace info-block zero-fields

2019-07-19T00:08:07+00:00

At namespace creation time there is the potential for the "expected to
be zero" fields of a 'pfn' info-block to be filled with indeterminate
data.  While the kernel buffer is zeroed on allocation it is immediately
overwritten by nd_pfn_validate() filling it with the current contents of
the on-media info-block location.  For fields like, 'flags' and the
'padding' it potentially means that future implementations can not rely on
those fields being zero.

In preparation to stop using the 'start_pad' and 'end_trunc' fields for
section alignment, arrange for fields that are not explicitly
initialized to be guaranteed zero.  Bump the minor version to indicate
it is safe to assume the 'padding' and 'flags' are zero.  Otherwise,
this corruption is expected to benign since all other critical fields
are explicitly initialized.

Note The cc: stable is about spreading this new policy to as many
kernels as possible not fixing an issue in those kernels.  It is not
until the change titled "libnvdimm/pfn: Stop padding pmem namespaces to
section alignment" where this improper initialization becomes a problem.
So if someone decides to backport "libnvdimm/pfn: Stop padding pmem
namespaces to section alignment" (which is not tagged for stable), make
sure this pre-requisite is flagged.

Link: http://lkml.kernel.org/r/156092356065.979959.6681003754765958296.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 32ab0a3f5170 ("libnvdimm, pmem: 'struct page' for pmem")
Signed-off-by: Dan Williams 
Tested-by: Aneesh Kumar K.V 	[ppc64]
Cc: 
Cc: David Hildenbrand 
Cc: Jane Chu 
Cc: Jeff Moyer 
Cc: Jérôme Glisse 
Cc: Jonathan Corbet 
Cc: Logan Gunthorpe 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Oscar Salvador 
Cc: Pavel Tatashin 
Cc: Toshi Kani 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Cc: Jason Gunthorpe 
Cc: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

driver-core, libnvdimm: Let device subsystems add local lockdep coverage

2019-07-18T23:23:27+00:00

For good reason, the standard device_lock() is marked
lockdep_set_novalidate_class() because there is simply no sane way to
describe the myriad ways the device_lock() ordered with other locks.
However, that leaves subsystems that know their own local device_lock()
ordering rules to find lock ordering mistakes manually. Instead,
introduce an optional / additional lockdep-enabled lock that a subsystem
can acquire in all the same paths that the device_lock() is acquired.

A conversion of the NFIT driver and NVDIMM subsystem to a
lockdep-validate device_lock() scheme is included. The
debug_nvdimm_lock() implementation implements the correct lock-class and
stacking order for the libnvdimm device topology hierarchy.

Yes, this is a hack, but hopefully it is a useful hack for other
subsystems device_lock() debug sessions. Quoting Greg:

    "Yeah, it feels a bit hacky but it's really up to a subsystem to mess up
     using it as much as anything else, so user beware :)

     I don't object to it if it makes things easier for you to debug."

Cc: Ingo Molnar 
Cc: Ira Weiny 
Cc: Will Deacon 
Cc: Dave Jiang 
Cc: Keith Busch 
Cc: Peter Zijlstra 
Cc: Vishal Verma 
Cc: "Rafael J. Wysocki" 
Cc: Greg Kroah-Hartman 
Signed-off-by: Dan Williams 
Acked-by: Greg Kroah-Hartman 
Reviewed-by: Ira Weiny 
Link: https://lore.kernel.org/r/156341210661.292348.7014034644265455704.stgit@dwillia2-desk3.amr.corp.intel.com

libnvdimm/bus: Fix wait_nvdimm_bus_probe_idle() ABBA deadlock

2019-07-18T23:23:16+00:00

A multithreaded namespace creation/destruction stress test currently
deadlocks with the following lockup signature:

    INFO: task ndctl:2924 blocked for more than 122 seconds.
          Tainted: G           OE     5.2.0-rc4+ #3382
    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
    ndctl           D    0  2924   1176 0x00000000
    Call Trace:
     ? __schedule+0x27e/0x780
     schedule+0x30/0xb0
     wait_nvdimm_bus_probe_idle+0x8a/0xd0 [libnvdimm]
     ? finish_wait+0x80/0x80
     uuid_store+0xe6/0x2e0 [libnvdimm]
     kernfs_fop_write+0xf0/0x1a0
     vfs_write+0xb7/0x1b0
     ksys_write+0x5c/0xd0
     do_syscall_64+0x60/0x240

     INFO: task ndctl:2923 blocked for more than 122 seconds.
           Tainted: G           OE     5.2.0-rc4+ #3382
     "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
     ndctl           D    0  2923   1175 0x00000000
     Call Trace:
      ? __schedule+0x27e/0x780
      ? __mutex_lock+0x489/0x910
      schedule+0x30/0xb0
      schedule_preempt_disabled+0x11/0x20
      __mutex_lock+0x48e/0x910
      ? nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm]
      ? __lock_acquire+0x23f/0x1710
      ? nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm]
      nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm]
      __dax_pmem_probe+0x5e/0x210 [dax_pmem_core]
      ? nvdimm_bus_probe+0x1d0/0x2c0 [libnvdimm]
      dax_pmem_probe+0xc/0x20 [dax_pmem]
      nvdimm_bus_probe+0x90/0x2c0 [libnvdimm]
      really_probe+0xef/0x390
      driver_probe_device+0xb4/0x100

In this sequence an 'nd_dax' device is being probed and trying to take
the lock on its backing namespace to validate that the 'nd_dax' device
indeed has exclusive access to the backing namespace. Meanwhile, another
thread is trying to update the uuid property of that same backing
namespace. So one thread is in the probe path trying to acquire the
lock, and the other thread has acquired the lock and tries to flush the
probe path.

Fix this deadlock by not holding the namespace device_lock over the
wait_nvdimm_bus_probe_idle() synchronization step. In turn this requires
the device_lock to be held on entry to wait_nvdimm_bus_probe_idle() and
subsequently dropped internally to wait_nvdimm_bus_probe_idle().

Cc: 
Fixes: bf9bccc14c05 ("libnvdimm: pmem label sets and namespace instantiation")
Cc: Vishal Verma 
Tested-by: Jane Chu 
Link: https://lore.kernel.org/r/156341210094.292348.2384694131126767789.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams

libnvdimm/bus: Stop holding nvdimm_bus_list_mutex over __nd_ioctl()

2019-07-18T23:23:02+00:00

In preparation for fixing a deadlock between wait_for_bus_probe_idle()
and the nvdimm_bus_list_mutex arrange for __nd_ioctl() without
nvdimm_bus_list_mutex held. This also unifies the 'dimm' and 'bus' level
ioctls into a common nd_ioctl() preamble implementation.

Marked for -stable as it is a pre-requisite for a follow-on fix.

Cc: 
Fixes: bf9bccc14c05 ("libnvdimm: pmem label sets and namespace instantiation")
Cc: Vishal Verma 
Tested-by: Jane Chu 
Link: https://lore.kernel.org/r/156341209518.292348.7183897251740665198.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams

libnvdimm/bus: Prepare the nd_ioctl() path to be re-entrant

2019-07-18T23:22:35+00:00

In preparation for not holding a lock over the execution of nd_ioctl(),
update the implementation to allow multiple threads to be attempting
ioctls at the same time. The bus lock still prevents multiple in-flight
->ndctl() invocations from corrupting each other's state, but static
global staging buffers are moved to the heap.

Reported-by: Vishal Verma 
Reviewed-by: Vishal Verma 
Tested-by: Vishal Verma 
Link: https://lore.kernel.org/r/156341208947.292348.10560140326807607481.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams

libnvdimm/region: Register badblocks before namespaces

2019-07-18T23:22:19+00:00

Namespace activation expects to be able to reference region badblocks.
The following warning sometimes triggers when asynchronous namespace
activation races in front of the completion of namespace probing. Move
all possible namespace probing after region badblocks initialization.

Otherwise, lockdep sometimes catches the uninitialized state of the
badblocks seqlock with stack trace signatures like:

    INFO: trying to register non-static key.
    pmem2: detected capacity change from 0 to 136365211648
    the code is fine but needs lockdep annotation.
    turning off the locking correctness validator.
    CPU: 9 PID: 358 Comm: kworker/u80:5 Tainted: G           OE     5.2.0-rc4+ #3382
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
    Workqueue: events_unbound async_run_entry_fn
    Call Trace:
     dump_stack+0x85/0xc0
    pmem1.12: detected capacity change from 0 to 8589934592
     register_lock_class+0x56a/0x570
     ? check_object+0x140/0x270
     __lock_acquire+0x80/0x1710
     ? __mutex_lock+0x39d/0x910
     lock_acquire+0x9e/0x180
     ? nd_pfn_validate+0x28f/0x440 [libnvdimm]
     badblocks_check+0x93/0x1f0
     ? nd_pfn_validate+0x28f/0x440 [libnvdimm]
     nd_pfn_validate+0x28f/0x440 [libnvdimm]
     ? lockdep_hardirqs_on+0xf0/0x180
     nd_dax_probe+0x9a/0x120 [libnvdimm]
     nd_pmem_probe+0x6d/0x180 [nd_pmem]
     nvdimm_bus_probe+0x90/0x2c0 [libnvdimm]

Fixes: 48af2f7e52f4 ("libnvdimm, pfn: during init, clear errors...")
Cc: 
Cc: Vishal Verma 
Reviewed-by: Vishal Verma 
Link: https://lore.kernel.org/r/156341208365.292348.1547528796026249120.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams