xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages

Browse Source 
An upcoming patch changes and complicates the refcounting and especially
the "put page" aspects of it.  In order to keep everything clean,
refactor the devmap page release routines:

* Rename put_devmap_managed_page() to page_is_devmap_managed(), and
  limit the functionality to "read only": return a bool, with no side
  effects.

* Add a new routine, put_devmap_managed_page(), to handle decrementing
  the refcount for ZONE_DEVICE pages.

* Change callers (just release_pages() and put_page()) to check
  page_is_devmap_managed() before calling the new
  put_devmap_managed_page() routine.  This is a performance point:
  put_page() is a hot path, so we need to avoid non- inline function calls
  where possible.

* Rename __put_devmap_managed_page() to free_devmap_managed_page(), and
  limit the functionality to unconditionally freeing a devmap page.

This is originally based on a separate patch by Ira Weiny, which applied
to an early version of the put_user_page() experiments.  Since then,
Jérôme Glisse suggested the refactoring described above.

Link: http://lkml.kernel.org/r/20200107224558.2362728-5-jhubbard@nvidia.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Suggested-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
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: Leon Romanovsky <leonro@mellanox.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
John Hubbard
2020-01-30 22:12:28 -08:00
committed by Linus Torvalds
parent 429589d647
commit 07d8026995
3 changed files with 40 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
mm/memremap.c
View File

@@ -411,20 +411,8 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
EXPORT_SYMBOL_GPL(get_dev_pagemap);
#ifdef CONFIG_DEV_PAGEMAP_OPS
void __put_devmap_managed_page(struct page *page)
void free_devmap_managed_page(struct page *page)
{
int count = page_ref_dec_return(page);
/* 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);
@@ -461,5 +449,4 @@ void __put_devmap_managed_page(struct page *page)
page->mapping = NULL;
page->pgmap->ops->page_free(page);
}
EXPORT_SYMBOL(__put_devmap_managed_page);
#endif /* CONFIG_DEV_PAGEMAP_OPS */