From 736f0e03564729a5ba609c2c4fcb37ff1e92ede4 Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Mon, 12 Aug 2024 15:42:07 +0800 Subject: [PATCH] mm: shmem: support large folio allocation for shmem_replace_folio() To support large folio swapin for shmem in the following patches, add large folio allocation for the new replacement folio in shmem_replace_folio(). Moreover large folios occupy N consecutive entries in the swap cache instead of using multi-index entries like the page cache, therefore we should replace each consecutive entries in the swap cache instead of using the shmem_replace_entry(). As well as updating statistics and folio reference count using the number of pages in the folio. [baolin.wang@linux.alibaba.com: fix the gfp flag for large folio allocation] Link: https://lkml.kernel.org/r/5b1e9c5a-7f61-4d97-a8d7-41767ca04c77@linux.alibaba.com [baolin.wang@linux.alibaba.com: fix build without CONFIG_TRANSPARENT_HUGEPAGE] Link: https://lkml.kernel.org/r/8c03467c-63b2-43b4-9851-222d4188725c@linux.alibaba.com Link: https://lkml.kernel.org/r/a41138ecc857ef13e7c5ffa0174321e9e2c9970a.1723434324.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang Cc: Barry Song Cc: Chris Li Cc: Daniel Gomez Cc: David Hildenbrand Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Kefeng Wang Cc: Lance Yang Cc: Matthew Wilcox Cc: Pankaj Raghav Cc: Ryan Roberts Cc: Yang Shi Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/shmem.c | 74 +++++++++++++++++++++++++++++++++--------------------- 1 file changed, 46 insertions(+), 28 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index f6bab42180ea..e63393ced001 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -155,7 +155,7 @@ static unsigned long shmem_default_max_inodes(void) static int shmem_swapin_folio(struct inode *inode, pgoff_t index, struct folio **foliop, enum sgp_type sgp, gfp_t gfp, - struct mm_struct *fault_mm, vm_fault_t *fault_type); + struct vm_area_struct *vma, vm_fault_t *fault_type); static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) { @@ -1887,30 +1887,35 @@ static bool shmem_should_replace_folio(struct folio *folio, gfp_t gfp) } static int shmem_replace_folio(struct folio **foliop, gfp_t gfp, - struct shmem_inode_info *info, pgoff_t index) + struct shmem_inode_info *info, pgoff_t index, + struct vm_area_struct *vma) { - struct folio *old, *new; - struct address_space *swap_mapping; - swp_entry_t entry; - pgoff_t swap_index; - int error; - - old = *foliop; - entry = old->swap; - swap_index = swap_cache_index(entry); - swap_mapping = swap_address_space(entry); + struct folio *new, *old = *foliop; + swp_entry_t entry = old->swap; + struct address_space *swap_mapping = swap_address_space(entry); + pgoff_t swap_index = swap_cache_index(entry); + XA_STATE(xas, &swap_mapping->i_pages, swap_index); + int nr_pages = folio_nr_pages(old); + int error = 0, i; /* * We have arrived here because our zones are constrained, so don't * limit chance of success by further cpuset and node constraints. */ gfp &= ~GFP_CONSTRAINT_MASK; - VM_BUG_ON_FOLIO(folio_test_large(old), old); - new = shmem_alloc_folio(gfp, 0, info, index); +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + if (nr_pages > 1) { + gfp_t huge_gfp = vma_thp_gfp_mask(vma); + + gfp = limit_gfp_mask(huge_gfp, gfp); + } +#endif + + new = shmem_alloc_folio(gfp, folio_order(old), info, index); if (!new) return -ENOMEM; - folio_get(new); + folio_ref_add(new, nr_pages); folio_copy(new, old); flush_dcache_folio(new); @@ -1920,18 +1925,25 @@ static int shmem_replace_folio(struct folio **foliop, gfp_t gfp, new->swap = entry; folio_set_swapcache(new); - /* - * Our caller will very soon move newpage out of swapcache, but it's - * a nice clean interface for us to replace oldpage by newpage there. - */ + /* Swap cache still stores N entries instead of a high-order entry */ xa_lock_irq(&swap_mapping->i_pages); - error = shmem_replace_entry(swap_mapping, swap_index, old, new); + for (i = 0; i < nr_pages; i++) { + void *item = xas_load(&xas); + + if (item != old) { + error = -ENOENT; + break; + } + + xas_store(&xas, new); + xas_next(&xas); + } if (!error) { mem_cgroup_replace_folio(old, new); - __lruvec_stat_mod_folio(new, NR_FILE_PAGES, 1); - __lruvec_stat_mod_folio(new, NR_SHMEM, 1); - __lruvec_stat_mod_folio(old, NR_FILE_PAGES, -1); - __lruvec_stat_mod_folio(old, NR_SHMEM, -1); + __lruvec_stat_mod_folio(new, NR_FILE_PAGES, nr_pages); + __lruvec_stat_mod_folio(new, NR_SHMEM, nr_pages); + __lruvec_stat_mod_folio(old, NR_FILE_PAGES, -nr_pages); + __lruvec_stat_mod_folio(old, NR_SHMEM, -nr_pages); } xa_unlock_irq(&swap_mapping->i_pages); @@ -1951,7 +1963,12 @@ static int shmem_replace_folio(struct folio **foliop, gfp_t gfp, old->private = NULL; folio_unlock(old); - folio_put_refs(old, 2); + /* + * The old folio are removed from swap cache, drop the 'nr_pages' + * reference, as well as one temporary reference getting from swap + * cache. + */ + folio_put_refs(old, nr_pages + 1); return error; } @@ -1990,10 +2007,11 @@ static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index, */ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, struct folio **foliop, enum sgp_type sgp, - gfp_t gfp, struct mm_struct *fault_mm, + gfp_t gfp, struct vm_area_struct *vma, vm_fault_t *fault_type) { struct address_space *mapping = inode->i_mapping; + struct mm_struct *fault_mm = vma ? vma->vm_mm : NULL; struct shmem_inode_info *info = SHMEM_I(inode); struct swap_info_struct *si; struct folio *folio = NULL; @@ -2054,7 +2072,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, arch_swap_restore(folio_swap(swap, folio), folio); if (shmem_should_replace_folio(folio, gfp)) { - error = shmem_replace_folio(&folio, gfp, info, index); + error = shmem_replace_folio(&folio, gfp, info, index, vma); if (error) goto failed; } @@ -2135,7 +2153,7 @@ repeat: if (xa_is_value(folio)) { error = shmem_swapin_folio(inode, index, &folio, - sgp, gfp, fault_mm, fault_type); + sgp, gfp, vma, fault_type); if (error == -EEXIST) goto repeat; -- 2.50.1