[PATCH 4.10 45/69] libnvdimm: band aid btt vs clear poison locking

Greg Kroah-Hartman
2017-04-19T14:39:39Z

From: Dan Williams <dan.j.williams@intel.com>

commit 4aa5615e080a9855e607accc75b07ab79b252dde upstream.

The following warning results from holding a lane spinlock,
preempt_disable(), or the btt map spinlock and then trying to take the
reconfig_mutex to walk the poison list and potentially add new entries.

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747
in_atomic(): 1, irqs_disabled(): 0, pid: 17159, name: dd
[..]
Call Trace:
dump_stack+0x85/0xc8
___might_sleep+0x184/0x250
__might_sleep+0x4a/0x90
__mutex_lock+0x58/0x9b0
? nvdimm_bus_lock+0x21/0x30 [libnvdimm]
? __nvdimm_bus_badblocks_clear+0x2f/0x60 [libnvdimm]
? acpi_nfit_forget_poison+0x79/0x80 [nfit]
? _raw_spin_unlock+0x27/0x40
mutex_lock_nested+0x1b/0x20
nvdimm_bus_lock+0x21/0x30 [libnvdimm]
nvdimm_forget_poison+0x25/0x50 [libnvdimm]
nvdimm_clear_poison+0x106/0x140 [libnvdimm]
nsio_rw_bytes+0x164/0x270 [libnvdimm]
btt_write_pg+0x1de/0x3e0 [nd_btt]
? blk_queue_enter+0x30/0x290
btt_make_request+0x11a/0x310 [nd_btt]
? blk_queue_enter+0xb7/0x290
? blk_queue_enter+0x30/0x290
generic_make_request+0x118/0x3b0

As a minimal fix, disable error clearing when the BTT is enabled for the
namespace. For the final fix a larger rework of the poison list locking
is needed.

Note that this is not a problem in the blk case since that path never
calls nvdimm_clear_poison().

Fixes: 82bf1037f2ca ("libnvdimm: check and clear poison before writing to pmem")
Cc: Dave Jiang <dave.jiang@intel.com>
[jeff: dynamically disable error clearing in the btt case]
Suggested-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/nvdimm/claim.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/nvdimm/claim.c
+++ b/drivers/nvdimm/claim.c
@@ -243,7 +243,15 @@ static int nsio_rw_bytes(struct nd_names
}

if (unlikely(is_bad_pmem(&nsio->bb, sector, sz_align))) {
- if (IS_ALIGNED(offset, 512) && IS_ALIGNED(size, 512)) {
+ /*
+ * FIXME: nsio_rw_bytes() may be called from atomic
+ * context in the btt case and nvdimm_clear_poison()
+ * takes a sleeping lock. Until the locking can be
+ * reworked this capability requires that the namespace
+ * is not claimed by btt.
+ */
+ if (IS_ALIGNED(offset, 512) && IS_ALIGNED(size, 512)
+ && (!ndns->claim || !is_nd_btt(ndns->claim))) {
long cleared;

cleared = nvdimm_clear_poison(&ndns->dev, offset, size);