mm: swap: extend swap_shmem_alloc() to support batch SWAP_MAP_SHMEM flag setting

Patch series "support large folio swap-out and swap-in for shmem", v5.

Shmem will support large folio allocation [1] [2] to get a better
performance, however, the memory reclaim still splits the precious large
folios when trying to swap-out shmem, which may lead to the memory
fragmentation issue and can not take advantage of the large folio for
shmeme.

Moreover, the swap code already supports for swapping out large folio
without split, and large folio swap-in[3] series is queued into
mm-unstable branch.  Hence this patch set also supports the large folio
swap-out and swap-in for shmem.

This patch (of 9):

To support shmem large folio swap operations, add a new parameter to
swap_shmem_alloc() that allows batch SWAP_MAP_SHMEM flag setting for shmem
swap entries.

While we are at it, using folio_nr_pages() to get the number of pages of
the folio as a preparation.

Link: https://lkml.kernel.org/r/cover.1723434324.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/99f64115d04b285e009580eb177352c57119ffd0.1723434324.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 1c8f844a9f0f268bdb14ee79d4e9c93caeebf1e4..248db1dd78122de4e01b229d75804ea2a0036db2 100644 (file)
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -481,7 +481,7 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry);
 extern swp_entry_t get_swap_page_of_type(int);
 extern int get_swap_pages(int n, swp_entry_t swp_entries[], int order);
 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
-extern void swap_shmem_alloc(swp_entry_t);
+extern void swap_shmem_alloc(swp_entry_t, int);
 extern int swap_duplicate(swp_entry_t);
 extern int swapcache_prepare(swp_entry_t entry, int nr);
 extern void swap_free_nr(swp_entry_t entry, int nr_pages);
@@ -548,7 +548,7 @@ static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
        return 0;
 }
 
-static inline void swap_shmem_alloc(swp_entry_t swp)
+static inline void swap_shmem_alloc(swp_entry_t swp, int nr)
 {
 }
 

diff --git a/mm/shmem.c b/mm/shmem.c
index 4a5254bfd61061e2a1be0ca78f69576e1c1198e7..22cdc10f27ea32714a06414359da248afb6860a6 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1452,6 +1452,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
        struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
        swp_entry_t swap;
        pgoff_t index;
+       int nr_pages;
 
        /*
         * Our capabilities prevent regular writeback or sync from ever calling
@@ -1484,6 +1485,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
        }
 
        index = folio->index;
+       nr_pages = folio_nr_pages(folio);
 
        /*
         * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
@@ -1536,8 +1538,8 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
        if (add_to_swap_cache(folio, swap,
                        __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
                        NULL) == 0) {
-               shmem_recalc_inode(inode, 0, 1);
-               swap_shmem_alloc(swap);
+               shmem_recalc_inode(inode, 0, nr_pages);
+               swap_shmem_alloc(swap, nr_pages);
                shmem_delete_from_page_cache(folio, swp_to_radix_entry(swap));
 
                mutex_unlock(&shmem_swaplist_mutex);

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 5e7cbdaf725d41cd64c11ce0dfdf643449933a30..8ff58be4054439c3a8a5f64def0b5095af9acc28 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3657,9 +3657,9 @@ unlock_out:
  * Help swapoff by noting that swap entry belongs to shmem/tmpfs
  * (in which case its reference count is never incremented).
  */
-void swap_shmem_alloc(swp_entry_t entry)
+void swap_shmem_alloc(swp_entry_t entry, int nr)
 {
-       __swap_duplicate(entry, SWAP_MAP_SHMEM, 1);
+       __swap_duplicate(entry, SWAP_MAP_SHMEM, nr);
 }
 
 /*