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mm: Add folio_put() 

If we know we have a folio, we can call folio_put() instead of put_page()
and save the overhead of calling compound_head().  Also skips the
devmap checks.

This commit looks like it should be a no-op, but actually saves 684 bytes
of text with the distro-derived config that I'm testing.  Some functions
grow a little while others shrink.  I presume the compiler is making
different inlining decisions.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-12-06 23:04:57 -05:00
parent c24016ac3a
commit b620f63358
1 changed files with 28 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
include/linux/mm.h
View File

@ -748,6 +748,11 @@ static inline int put_page_testzero(struct page *page)
return page_ref_dec_and_test(page);
}
static inline int folio_put_testzero(struct folio *folio)
{
return put_page_testzero(&folio->page);
}
/*
* Try to grab a ref unless the page has a refcount of zero, return false if
* that is the case.
@ -1247,9 +1252,28 @@ static inline __must_check bool try_get_page(struct page *page)
return true;
}
/**
* folio_put - Decrement the reference count on a folio.
* @folio: The folio.
*
* If the folio's reference count reaches zero, the memory will be
* released back to the page allocator and may be used by another
* allocation immediately. Do not access the memory or the struct folio
* after calling folio_put() unless you can be sure that it wasn't the
* last reference.
*
* Context: May be called in process or interrupt context, but not in NMI
* context. May be called while holding a spinlock.
*/
static inline void folio_put(struct folio *folio)
{
if (folio_put_testzero(folio))
__put_page(&folio->page);
}
static inline void put_page(struct page *page)
{
page = compound_head(page);
struct folio *folio = page_folio(page);
/*
* For devmap managed pages we need to catch refcount transition from
@ -1257,13 +1281,12 @@ static inline void put_page(struct page *page)
* need to inform the device driver through callback. See
* include/linux/memremap.h and HMM for details.
*/
if (page_is_devmap_managed(page)) {
put_devmap_managed_page(page);
if (page_is_devmap_managed(&folio->page)) {
put_devmap_managed_page(&folio->page);
return;
}
if (put_page_testzero(page))
__put_page(page);
folio_put(folio);
}
/*