mm/swap: fix release_pages() when releasing devmap pages
[ Upstream commit c5d6c45e90c49150670346967971e14576afd7f1 ]
release_pages() is an optimized version of a loop around put_page().
Unfortunately for devmap pages the logic is not entirely correct in
release_pages(). This is because device pages can be more than type
MEMORY_DEVICE_PUBLIC. There are in fact 4 types, private, public, FS DAX,
and PCI P2PDMA. Some of these have specific needs to "put" the page while
others do not.
This logic to handle any special needs is contained in
put_devmap_managed_page(). Therefore all devmap pages should be processed
by this function where we can contain the correct logic for a page put.
Handle all device type pages within release_pages() by calling
put_devmap_managed_page() on all devmap pages. If
put_devmap_managed_page() returns true the page has been put and we
continue with the next page. A false return of put_devmap_managed_page()
means the page did not require special processing and should fall to
"normal" processing.
This was found via code inspection while determining if release_pages()
and the new put_user_pages() could be interchangeable.[1]
[1] https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Cc: Jérôme Glisse <[email protected]>
Cc: Michal Hocko <[email protected]>
Reviewed-by: Dan Williams <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
Signed-off-by: Ira Weiny <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
1 file changed
