The patch titled
Subject: mm/khugepaged: try to free transhuge swapcache when possible
has been added to the -mm mm-unstable branch. Its filename is
mm-khugepaged-try-to-free-transhuge-swapcache-when-possible.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-khugepaged-try-to-free-transhuge-swapcache-when-possible.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm/khugepaged: try to free transhuge swapcache when possible
Date: Sat, 25 Jun 2022 17:28:16 +0800
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@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: NeilBrown <neilb@xxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Zach O'Keefe <zokeefe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/swap.h | 5 +++++
mm/khugepaged.c | 7 ++++++-
mm/swap.h | 5 -----
3 files changed, 11 insertions(+), 6 deletions(-)
--- a/include/linux/swap.h~mm-khugepaged-try-to-free-transhuge-swapcache-when-possible
+++ a/include/linux/swap.h
@@ -458,6 +458,7 @@ static inline unsigned long total_swapca
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 */
@@ -542,6 +543,10 @@ static inline void put_swap_device(struc
/* 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;
--- a/mm/khugepaged.c~mm-khugepaged-try-to-free-transhuge-swapcache-when-possible
+++ a/mm/khugepaged.c
@@ -716,7 +716,12 @@ static void __collapse_huge_page_copy(pt
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);
}
}
--- a/mm/swap.h~mm-khugepaged-try-to-free-transhuge-swapcache-when-possible
+++ a/mm/swap.h
@@ -41,7 +41,6 @@ void __delete_from_swap_cache(struct fol
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
return NULL;
}
-static inline void free_swap_cache(struct page *page)
-{
-}
-
static inline void show_swap_cache_info(void)
{
}
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-migration-remove-unneeded-lock-page-and-pagemovable-check.patch
mm-migration-return-errno-when-isolate_huge_page-failed.patch
mm-migration-fix-potential-pte_unmap-on-an-not-mapped-pte.patch
mm-swapfile-make-security_vm_enough_memory_mm-work-as-expected.patch
mm-swapfile-fix-possible-data-races-of-inuse_pages.patch
mm-swap-remove-swap_cache_info-statistics.patch
mm-vmscan-dont-try-to-reclaim-freed-folios.patch
mm-page_alloc-minor-clean-up-for-memmap_init_compound.patch
mm-madvise-minor-cleanup-for-swapin_walk_pmd_entry.patch
mm-mmapc-fix-missing-call-to-vm_unacct_memory-in-mmap_region.patch
mm-khugepaged-remove-unneeded-shmem_huge_enabled-check.patch
mm-khugepaged-stop-swapping-in-page-when-vm_fault_retry-occurs.patch
mm-khugepaged-trivial-typo-and-codestyle-cleanup.patch
mm-khugepaged-minor-cleanup-for-collapse_file.patch
mm-khugepaged-use-helper-macro-__attr_rw.patch
mm-khugepaged-remove-unneeded-return-value-of-khugepaged_add_pte_mapped_thp.patch
mm-khugepaged-try-to-free-transhuge-swapcache-when-possible.patch
