Commit 429589d6 authored by Dan Williams's avatar Dan Williams Committed by Linus Torvalds
Browse files

mm: Cleanup __put_devmap_managed_page() vs ->page_free() 

After the removal of the device-public infrastructure there are only 2
->page_free() call backs in the kernel.  One of those is a
device-private callback in the nouveau driver, the other is a generic
wakeup needed in the DAX case.  In the hopes that all ->page_free()
callbacks can be migrated to common core kernel functionality, move the
device-private specific actions in __put_devmap_managed_page() under the
is_device_private_page() conditional, including the ->page_free()
callback.  For the other page types just open-code the generic wakeup.

Yes, the wakeup is only needed in the MEMORY_DEVICE_FSDAX case, but it
does no harm in the MEMORY_DEVICE_DEVDAX and MEMORY_DEVICE_PCI_P2PDMA
case.

Link: http://lkml.kernel.org/r/20200107224558.2362728-4-jhubbard@nvidia.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Björn Töpel <bjorn.topel@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Leon Romanovsky <leonro@mellanox.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a707cdd5

drivers/nvdimm/pmem.c

+0 −6
Original line number Diff line number Diff line
@@ -337,13 +337,7 @@ static void pmem_release_disk(void *__pmem) 
	put_disk(pmem->disk);

}



static void pmem_pagemap_page_free(struct page *page)

{

	wake_up_var(&page->_refcount);

}



static const struct dev_pagemap_ops fsdax_pagemap_ops = {

	.page_free		= pmem_pagemap_page_free,

	.kill			= pmem_pagemap_kill,

	.cleanup		= pmem_pagemap_cleanup,

};

mm/memremap.c

+44 −36
Original line number Diff line number Diff line
@@ -27,7 +27,8 @@ static void devmap_managed_enable_put(void) 


static int devmap_managed_enable_get(struct dev_pagemap *pgmap)

{

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

	if (pgmap->type == MEMORY_DEVICE_PRIVATE &&

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

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

		return -EINVAL;

	}
@@ -414,11 +415,22 @@ void __put_devmap_managed_page(struct page *page) 
{

	int count = page_ref_dec_return(page);



	/*

	 * If refcount is 1 then page is freed and refcount is stable as nobody

	 * holds a reference on the page.

	 */

	if (count == 1) {

	/* still busy */

	if (count > 1)

		return;



	/* only triggered by the dev_pagemap shutdown path */

	if (count == 0) {

		__put_page(page);

		return;

	}



	/* notify page idle for dax */

	if (!is_device_private_page(page)) {

		wake_up_var(&page->_refcount);

		return;

	}



	/* Clear Active bit in case of parallel mark_page_accessed */

	__ClearPageActive(page);

	__ClearPageWaiters(page);
@@ -428,10 +440,10 @@ void __put_devmap_managed_page(struct page *page) 
	/*

	 * When a device_private page is freed, the page->mapping field

	 * may still contain a (stale) mapping value. For example, the

		 * lower bits of page->mapping may still identify the page as

		 * an anonymous page. Ultimately, this entire field is just

		 * stale and wrong, and it will cause errors if not cleared.

		 * One example is:

	 * lower bits of page->mapping may still identify the page as an

	 * anonymous page. Ultimately, this entire field is just stale

	 * and wrong, and it will cause errors if not cleared.  One

	 * example is:

	 *

	 *  migrate_vma_pages()

	 *    migrate_vma_insert_page()
@@ -446,12 +458,8 @@ void __put_devmap_managed_page(struct page *page) 
	 * handled differently or not done at all, so there is no need

	 * to clear page->mapping.

	 */

		if (is_device_private_page(page))

	page->mapping = NULL;



	page->pgmap->ops->page_free(page);

	} else if (!count)

		__put_page(page);

}

EXPORT_SYMBOL(__put_devmap_managed_page);

#endif /* CONFIG_DEV_PAGEMAP_OPS */

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