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Commit b3b454f6 authored by Dave Jiang's avatar Dave Jiang Committed by Dan Williams
Browse files

libnvdimm: fix clear poison locking with spinlock and GFP_NOWAIT allocation 



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

A spinlock is introduced to protect the poison list. This allows us to not
having to acquire the reconfig_mutex for touching the poison list. The
add_poison() function has been broken out into two helper functions. One to
allocate the poison entry and the other to apppend the entry. This allows us
to unlock the poison_lock in non-I/O path and continue to be able to allocate
the poison entry with GFP_KERNEL. We will use GFP_NOWAIT in the I/O path in
order to satisfy being in atomic context.

Reviewed-by: default avatarVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: default avatarDave Jiang <dave.jiang@intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent efebc711

drivers/nvdimm/bus.c

+4 −3
Original line number Diff line number Diff line
@@ -296,6 +296,7 @@ struct nvdimm_bus *nvdimm_bus_register(struct device *parent, 
	init_waitqueue_head(&nvdimm_bus->probe_wait);

	nvdimm_bus->id = ida_simple_get(&nd_ida, 0, 0, GFP_KERNEL);

	mutex_init(&nvdimm_bus->reconfig_mutex);

	spin_lock_init(&nvdimm_bus->poison_lock);

	if (nvdimm_bus->id < 0) {

		kfree(nvdimm_bus);

		return NULL;
@@ -364,9 +365,9 @@ static int nd_bus_remove(struct device *dev) 
	nd_synchronize();

	device_for_each_child(&nvdimm_bus->dev, NULL, child_unregister);



	nvdimm_bus_lock(&nvdimm_bus->dev);

	spin_lock(&nvdimm_bus->poison_lock);

	free_poison_list(&nvdimm_bus->poison_list);

	nvdimm_bus_unlock(&nvdimm_bus->dev);

	spin_unlock(&nvdimm_bus->poison_lock);



	nvdimm_bus_destroy_ndctl(nvdimm_bus);
@@ -990,7 +991,7 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm, 


		if (clear_err->cleared) {

			/* clearing the poison list we keep track of */

			__nvdimm_forget_poison(nvdimm_bus, clear_err->address,

			nvdimm_forget_poison(nvdimm_bus, clear_err->address,

					clear_err->cleared);



			/* now sync the badblocks lists */

drivers/nvdimm/core.c

+33 −23
Original line number Diff line number Diff line
@@ -518,6 +518,15 @@ void nvdimm_badblocks_populate(struct nd_region *nd_region, 
}

EXPORT_SYMBOL_GPL(nvdimm_badblocks_populate);



static void append_poison_entry(struct nvdimm_bus *nvdimm_bus,

		struct nd_poison *pl, u64 addr, u64 length)

{

	lockdep_assert_held(&nvdimm_bus->poison_lock);

	pl->start = addr;

	pl->length = length;

	list_add_tail(&pl->list, &nvdimm_bus->poison_list);

}



static int add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length,

			gfp_t flags)

{
@@ -527,19 +536,24 @@ static int add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length, 
	if (!pl)

		return -ENOMEM;



	pl->start = addr;

	pl->length = length;

	list_add_tail(&pl->list, &nvdimm_bus->poison_list);



	append_poison_entry(nvdimm_bus, pl, addr, length);

	return 0;

}



static int bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length)

{

	struct nd_poison *pl;

	struct nd_poison *pl, *pl_new;



	spin_unlock(&nvdimm_bus->poison_lock);

	pl_new = kzalloc(sizeof(*pl_new), GFP_KERNEL);

	spin_lock(&nvdimm_bus->poison_lock);



	if (list_empty(&nvdimm_bus->poison_list))

		return add_poison(nvdimm_bus, addr, length, GFP_KERNEL);

	if (list_empty(&nvdimm_bus->poison_list)) {

		if (!pl_new)

			return -ENOMEM;

		append_poison_entry(nvdimm_bus, pl_new, addr, length);

		return 0;

	}



	/*

	 * There is a chance this is a duplicate, check for those first.
@@ -551,6 +565,7 @@ static int bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length) 
			/* If length has changed, update this list entry */

			if (pl->length != length)

				pl->length = length;

			kfree(pl_new);

			return 0;

		}
@@ -559,30 +574,33 @@ static int bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length) 
	 * as any overlapping ranges will get resolved when the list is consumed

	 * and converted to badblocks

	 */

	return add_poison(nvdimm_bus, addr, length, GFP_KERNEL);

	if (!pl_new)

		return -ENOMEM;

	append_poison_entry(nvdimm_bus, pl_new, addr, length);



	return 0;

}



int nvdimm_bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length)

{

	int rc;



	nvdimm_bus_lock(&nvdimm_bus->dev);

	spin_lock(&nvdimm_bus->poison_lock);

	rc = bus_add_poison(nvdimm_bus, addr, length);

	nvdimm_bus_unlock(&nvdimm_bus->dev);

	spin_unlock(&nvdimm_bus->poison_lock);



	return rc;

}

EXPORT_SYMBOL_GPL(nvdimm_bus_add_poison);



void __nvdimm_forget_poison(struct nvdimm_bus *nvdimm_bus, phys_addr_t start,

void nvdimm_forget_poison(struct nvdimm_bus *nvdimm_bus, phys_addr_t start,

		unsigned int len)

{

	struct list_head *poison_list = &nvdimm_bus->poison_list;

	u64 clr_end = start + len - 1;

	struct nd_poison *pl, *next;



	lockdep_assert_held(&nvdimm_bus->reconfig_mutex);



	spin_lock(&nvdimm_bus->poison_lock);

	WARN_ON_ONCE(list_empty(poison_list));



	/*
@@ -629,21 +647,13 @@ void __nvdimm_forget_poison(struct nvdimm_bus *nvdimm_bus, phys_addr_t start, 
			u64 new_len = pl_end - new_start + 1;



			/* Add new entry covering the right half */

			add_poison(nvdimm_bus, new_start, new_len, GFP_NOIO);

			add_poison(nvdimm_bus, new_start, new_len, GFP_NOWAIT);

			/* Adjust this entry to cover the left half */

			pl->length = start - pl->start;

			continue;

		}

	}

}

EXPORT_SYMBOL_GPL(__nvdimm_forget_poison);



void nvdimm_forget_poison(struct nvdimm_bus *nvdimm_bus,

		phys_addr_t start, unsigned int len)

{

	nvdimm_bus_lock(&nvdimm_bus->dev);

	__nvdimm_forget_poison(nvdimm_bus, start, len);

	nvdimm_bus_unlock(&nvdimm_bus->dev);

	spin_unlock(&nvdimm_bus->poison_lock);

}

EXPORT_SYMBOL_GPL(nvdimm_forget_poison);

drivers/nvdimm/nd-core.h

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ struct nvdimm_bus { 
	struct list_head poison_list;

	struct list_head mapping_list;

	struct mutex reconfig_mutex;

	spinlock_t poison_lock;

};



struct nvdimm {

include/linux/libnvdimm.h

+0 −2
Original line number Diff line number Diff line
@@ -122,8 +122,6 @@ static inline struct nd_blk_region_desc *to_blk_region_desc( 
int nvdimm_bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length);

void nvdimm_forget_poison(struct nvdimm_bus *nvdimm_bus,

		phys_addr_t start, unsigned int len);

void __nvdimm_forget_poison(struct nvdimm_bus *nvdimm_bus,

		phys_addr_t start, unsigned int len);

struct nvdimm_bus *nvdimm_bus_register(struct device *parent,

		struct nvdimm_bus_descriptor *nfit_desc);

void nvdimm_bus_unregister(struct nvdimm_bus *nvdimm_bus);