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mm/khugepaged: try to free transhuge swapcache when possible 

Transhuge swapcaches won't be freed in __collapse_huge_page_copy().  It's
because release_pte_page() is not called for these pages and thus
free_page_and_swap_cache can't grab the page lock.  These pages won't be
freed from swap cache even if we are the only user until next time
reclaim.  It shouldn't hurt indeed, but we could try to free these pages
to save more memory for system.

Link: https://lkml.kernel.org/r/20220625092816.4856-8-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2022-06-25 17:28:16 +08:00 committed by akpm
parent 081c32564b
commit 1baec203b7
3 changed files with 11 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/swap.h
View File

@ -455,6 +455,7 @@ static inline unsigned long total_swapcache_pages(void)
return global_node_page_state(NR_SWAPCACHE);
}
extern void free_swap_cache(struct page *page);
extern void free_page_and_swap_cache(struct page *);
extern void free_pages_and_swap_cache(struct page **, int);
/* linux/mm/swapfile.c */
@ -539,6 +540,10 @@ static inline void put_swap_device(struct swap_info_struct *si)
/* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */
#define free_swap_and_cache(e) is_pfn_swap_entry(e)
static inline void free_swap_cache(struct page *page)
{
}
static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
{
return 0;

7
mm/khugepaged.c
View File

@ -755,7 +755,12 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) {
list_del(&src_page->lru);
release_pte_page(src_page);
mod_node_page_state(page_pgdat(src_page),
NR_ISOLATED_ANON + page_is_file_lru(src_page),
-compound_nr(src_page));
unlock_page(src_page);
free_swap_cache(src_page);
putback_lru_page(src_page);
}
}

5
mm/swap.h
View File

@ -41,7 +41,6 @@ void __delete_from_swap_cache(struct folio *folio,
void delete_from_swap_cache(struct folio *folio);
void clear_shadow_from_swap_cache(int type, unsigned long begin,
unsigned long end);
void free_swap_cache(struct page *page);
struct page *lookup_swap_cache(swp_entry_t entry,
struct vm_area_struct *vma,
unsigned long addr);
@ -81,10 +80,6 @@ static inline struct address_space *swap_address_space(swp_entry_t entry)
return NULL;
}
static inline void free_swap_cache(struct page *page)
{
}
static inline void show_swap_cache_info(void)
{
}