Commit 46b1ee38 authored by Ralph Campbell's avatar Ralph Campbell Committed by Linus Torvalds
Browse files

mm/mremap_pages: fix static key devmap_managed_key updates 



commit 6f42193f ("memremap: don't use a separate devm action for
devmap_managed_enable_get") changed the static key updates such that we
now call devmap_managed_enable_put() without doing the equivalent
devmap_managed_enable_get().

devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and
MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap
types too.  This results in the below warning when switching between
system-ram and devdax mode for devdax namespace.

   jump label: negative count!
   WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
   Modules linked in:
   ....

   NIP static_key_slow_try_dec+0x88/0xa0
   LR static_key_slow_try_dec+0x84/0xa0
   Call Trace:
     static_key_slow_try_dec+0x84/0xa0
     __static_key_slow_dec_cpuslocked+0x34/0xd0
     static_key_slow_dec+0x54/0xf0
     memunmap_pages+0x36c/0x500
     devm_action_release+0x30/0x50
     release_nodes+0x2f4/0x3e0
     device_release_driver_internal+0x17c/0x280
     bus_remove_device+0x124/0x210
     device_del+0x1d4/0x530
     unregister_dev_dax+0x48/0xe0
     devm_action_release+0x30/0x50
     release_nodes+0x2f4/0x3e0
     device_release_driver_internal+0x17c/0x280
     unbind_store+0x130/0x170
     drv_attr_store+0x40/0x60
     sysfs_kf_write+0x6c/0xb0
     kernfs_fop_write+0x118/0x280
     vfs_write+0xe8/0x2a0
     ksys_write+0x84/0x140
     system_call_exception+0x120/0x270
     system_call_common+0xf0/0x27c

Reported-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: default avatarRalph Campbell <rcampbell@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Tested-by: default avatarSachin Sant <sachinp@linux.vnet.ibm.com>
Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Link: https://lkml.kernel.org/r/20201023183222.13186-1-rcampbell@nvidia.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3cea11cd

mm/memremap.c

+16 −23
Original line number Diff line number Diff line
@@ -41,28 +41,24 @@ EXPORT_SYMBOL_GPL(memremap_compat_align); 
DEFINE_STATIC_KEY_FALSE(devmap_managed_key);

EXPORT_SYMBOL(devmap_managed_key);



static void devmap_managed_enable_put(void)

static void devmap_managed_enable_put(struct dev_pagemap *pgmap)

{

	if (pgmap->type == MEMORY_DEVICE_PRIVATE ||

	    pgmap->type == MEMORY_DEVICE_FS_DAX)

		static_branch_dec(&devmap_managed_key);

}



static int devmap_managed_enable_get(struct dev_pagemap *pgmap)

static void devmap_managed_enable_get(struct dev_pagemap *pgmap)

{

	if (pgmap->type == MEMORY_DEVICE_PRIVATE &&

	    (!pgmap->ops || !pgmap->ops->page_free)) {

		WARN(1, "Missing page_free method\n");

		return -EINVAL;

	}



	if (pgmap->type == MEMORY_DEVICE_PRIVATE ||

	    pgmap->type == MEMORY_DEVICE_FS_DAX)

		static_branch_inc(&devmap_managed_key);

	return 0;

}

#else

static int devmap_managed_enable_get(struct dev_pagemap *pgmap)

static void devmap_managed_enable_get(struct dev_pagemap *pgmap)

{

	return -EINVAL;

}

static void devmap_managed_enable_put(void)

static void devmap_managed_enable_put(struct dev_pagemap *pgmap)

{

}

#endif /* CONFIG_DEV_PAGEMAP_OPS */
@@ -169,7 +165,7 @@ void memunmap_pages(struct dev_pagemap *pgmap) 
		pageunmap_range(pgmap, i);



	WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");

	devmap_managed_enable_put();

	devmap_managed_enable_put(pgmap);

}

EXPORT_SYMBOL_GPL(memunmap_pages);
@@ -307,7 +303,6 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) 
		.pgprot = PAGE_KERNEL,

	};

	const int nr_range = pgmap->nr_range;

	bool need_devmap_managed = true;

	int error, i;



	if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
@@ -323,6 +318,10 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) 
			WARN(1, "Missing migrate_to_ram method\n");

			return ERR_PTR(-EINVAL);

		}

		if (!pgmap->ops->page_free) {

			WARN(1, "Missing page_free method\n");

			return ERR_PTR(-EINVAL);

		}

		if (!pgmap->owner) {

			WARN(1, "Missing owner\n");

			return ERR_PTR(-EINVAL);
@@ -336,11 +335,9 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) 
		}

		break;

	case MEMORY_DEVICE_GENERIC:

		need_devmap_managed = false;

		break;

	case MEMORY_DEVICE_PCI_P2PDMA:

		params.pgprot = pgprot_noncached(params.pgprot);

		need_devmap_managed = false;

		break;

	default:

		WARN(1, "Invalid pgmap type %d\n", pgmap->type);
@@ -364,11 +361,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) 
		}

	}



	if (need_devmap_managed) {

		error = devmap_managed_enable_get(pgmap);

		if (error)

			return ERR_PTR(error);

	}

	devmap_managed_enable_get(pgmap);



	/*

	 * Clear the pgmap nr_range as it will be incremented for each

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