libnvdimm: band aid btt vs clear poison locking

djbw · djbw · commit 4aa5615e080a · 2017-04-10T17:21:45.000-07:00
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(). Cc: <stable@vger.kernel.org> Fixes: 82bf103 ("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>
diff --git a/drivers/nvdimm/claim.c b/drivers/nvdimm/claim.c
@@ -243,7 +243,15 @@ static int nsio_rw_bytes(struct nd_namespace_common *ndns,
 	}
 
 	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);
