[PATCH 13/23] thp, mm: allocate huge pages in grab_cache_page_write_begin()
From: Kirill A. Shutemov <hidden>
Date: 2013-08-04 02:17:15
Also in:
linux-fsdevel, lkml
Subsystem:
filesystems (vfs and infrastructure), memory management, page cache, the rest · Maintainers:
Alexander Viro, Christian Brauner, Andrew Morton, Matthew Wilcox, Linus Torvalds
From: "Kirill A. Shutemov" <redacted> Try to allocate huge page if flags has AOP_FLAG_TRANSHUGE. If, for some reason, it's not possible allocate a huge page at this possition, it returns NULL. Caller should take care of fallback to small pages. Signed-off-by: Kirill A. Shutemov <redacted> --- include/linux/fs.h | 1 + mm/filemap.c | 24 ++++++++++++++++++++++-- 2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b09ddc0..d5f58b3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -282,6 +282,7 @@ enum positive_aop_returns { #define AOP_FLAG_NOFS 0x0004 /* used by filesystem to direct * helper code (eg buffer layer) * to clear GFP_FS from alloc */ +#define AOP_FLAG_TRANSHUGE 0x0008 /* allocate transhuge page */ /* * oh the beauties of C type declarations.
diff --git a/mm/filemap.c b/mm/filemap.c
index 28f4927..b17ebb9 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c@@ -2313,18 +2313,38 @@ struct page *grab_cache_page_write_begin(struct address_space *mapping, gfp_t gfp_mask; struct page *page; gfp_t gfp_notmask = 0; + bool must_use_thp = (flags & AOP_FLAG_TRANSHUGE) && + IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE); + gfp_mask = mapping_gfp_mask(mapping); + if (must_use_thp) { + BUG_ON(index & HPAGE_CACHE_INDEX_MASK); + BUG_ON(!(gfp_mask & __GFP_COMP)); + } if (mapping_cap_account_dirty(mapping)) gfp_mask |= __GFP_WRITE; if (flags & AOP_FLAG_NOFS) gfp_notmask = __GFP_FS; repeat: page = find_lock_page(mapping, index); - if (page) + if (page) { + if (must_use_thp && !PageTransHuge(page)) { + unlock_page(page); + page_cache_release(page); + return NULL; + } goto found; + } - page = __page_cache_alloc(gfp_mask & ~gfp_notmask); + if (must_use_thp) { + page = alloc_pages(gfp_mask & ~gfp_notmask, HPAGE_PMD_ORDER); + if (page) + count_vm_event(THP_WRITE_ALLOC); + else + count_vm_event(THP_WRITE_ALLOC_FAILED); + } else + page = __page_cache_alloc(gfp_mask & ~gfp_notmask); if (!page) return NULL; status = add_to_page_cache_lru(page, mapping, index,
--
1.8.3.2
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