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![Kirill A. Shutemov](/assets/img/avatar_default.png)
We are going to rework how compound_head() work. It will not use page->first_page as we have it now. The only other user of page->first_page beyond compound pages is zsmalloc. Let's use page->private instead of page->first_page here. It occupies the same storage space. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2038 lines
48 KiB
C
2038 lines
48 KiB
C
/*
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* zsmalloc memory allocator
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*
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* Copyright (C) 2011 Nitin Gupta
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* Copyright (C) 2012, 2013 Minchan Kim
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*
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* This code is released using a dual license strategy: BSD/GPL
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* You can choose the license that better fits your requirements.
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*
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* Released under the terms of 3-clause BSD License
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* Released under the terms of GNU General Public License Version 2.0
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*/
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/*
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* Following is how we use various fields and flags of underlying
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* struct page(s) to form a zspage.
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*
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* Usage of struct page fields:
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* page->private: points to the first component (0-order) page
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* page->index (union with page->freelist): offset of the first object
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* starting in this page. For the first page, this is
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* always 0, so we use this field (aka freelist) to point
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* to the first free object in zspage.
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* page->lru: links together all component pages (except the first page)
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* of a zspage
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*
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* For _first_ page only:
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*
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* page->private: refers to the component page after the first page
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* If the page is first_page for huge object, it stores handle.
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* Look at size_class->huge.
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* page->freelist: points to the first free object in zspage.
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* Free objects are linked together using in-place
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* metadata.
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* page->objects: maximum number of objects we can store in this
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* zspage (class->zspage_order * PAGE_SIZE / class->size)
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* page->lru: links together first pages of various zspages.
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* Basically forming list of zspages in a fullness group.
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* page->mapping: class index and fullness group of the zspage
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* page->inuse: the number of objects that are used in this zspage
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*
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* Usage of struct page flags:
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* PG_private: identifies the first component page
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* PG_private2: identifies the last component page
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*
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/bitops.h>
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#include <linux/errno.h>
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#include <linux/highmem.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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#include <asm/tlbflush.h>
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#include <asm/pgtable.h>
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#include <linux/cpumask.h>
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#include <linux/cpu.h>
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#include <linux/vmalloc.h>
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#include <linux/preempt.h>
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#include <linux/spinlock.h>
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#include <linux/types.h>
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#include <linux/debugfs.h>
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#include <linux/zsmalloc.h>
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#include <linux/zpool.h>
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/*
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* This must be power of 2 and greater than of equal to sizeof(link_free).
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* These two conditions ensure that any 'struct link_free' itself doesn't
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* span more than 1 page which avoids complex case of mapping 2 pages simply
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* to restore link_free pointer values.
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*/
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#define ZS_ALIGN 8
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/*
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* A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
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* pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
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*/
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#define ZS_MAX_ZSPAGE_ORDER 2
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#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
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#define ZS_HANDLE_SIZE (sizeof(unsigned long))
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/*
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* Object location (<PFN>, <obj_idx>) is encoded as
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* as single (unsigned long) handle value.
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*
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* Note that object index <obj_idx> is relative to system
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* page <PFN> it is stored in, so for each sub-page belonging
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* to a zspage, obj_idx starts with 0.
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*
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* This is made more complicated by various memory models and PAE.
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*/
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#ifndef MAX_PHYSMEM_BITS
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#ifdef CONFIG_HIGHMEM64G
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#define MAX_PHYSMEM_BITS 36
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#else /* !CONFIG_HIGHMEM64G */
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/*
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* If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
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* be PAGE_SHIFT
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*/
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#define MAX_PHYSMEM_BITS BITS_PER_LONG
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#endif
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#endif
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#define _PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT)
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/*
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* Memory for allocating for handle keeps object position by
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* encoding <page, obj_idx> and the encoded value has a room
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* in least bit(ie, look at obj_to_location).
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* We use the bit to synchronize between object access by
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* user and migration.
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*/
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#define HANDLE_PIN_BIT 0
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/*
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* Head in allocated object should have OBJ_ALLOCATED_TAG
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* to identify the object was allocated or not.
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* It's okay to add the status bit in the least bit because
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* header keeps handle which is 4byte-aligned address so we
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* have room for two bit at least.
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*/
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#define OBJ_ALLOCATED_TAG 1
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#define OBJ_TAG_BITS 1
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#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
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#define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
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#define MAX(a, b) ((a) >= (b) ? (a) : (b))
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/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
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#define ZS_MIN_ALLOC_SIZE \
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MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
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/* each chunk includes extra space to keep handle */
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#define ZS_MAX_ALLOC_SIZE PAGE_SIZE
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/*
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* On systems with 4K page size, this gives 255 size classes! There is a
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* trader-off here:
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* - Large number of size classes is potentially wasteful as free page are
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* spread across these classes
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* - Small number of size classes causes large internal fragmentation
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* - Probably its better to use specific size classes (empirically
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* determined). NOTE: all those class sizes must be set as multiple of
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* ZS_ALIGN to make sure link_free itself never has to span 2 pages.
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*
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* ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
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* (reason above)
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*/
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#define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> 8)
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/*
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* We do not maintain any list for completely empty or full pages
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*/
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enum fullness_group {
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ZS_ALMOST_FULL,
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ZS_ALMOST_EMPTY,
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_ZS_NR_FULLNESS_GROUPS,
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ZS_EMPTY,
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ZS_FULL
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};
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enum zs_stat_type {
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OBJ_ALLOCATED,
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OBJ_USED,
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CLASS_ALMOST_FULL,
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CLASS_ALMOST_EMPTY,
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};
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#ifdef CONFIG_ZSMALLOC_STAT
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#define NR_ZS_STAT_TYPE (CLASS_ALMOST_EMPTY + 1)
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#else
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#define NR_ZS_STAT_TYPE (OBJ_USED + 1)
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#endif
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struct zs_size_stat {
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unsigned long objs[NR_ZS_STAT_TYPE];
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};
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#ifdef CONFIG_ZSMALLOC_STAT
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static struct dentry *zs_stat_root;
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#endif
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/*
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* number of size_classes
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*/
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static int zs_size_classes;
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/*
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* We assign a page to ZS_ALMOST_EMPTY fullness group when:
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* n <= N / f, where
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* n = number of allocated objects
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* N = total number of objects zspage can store
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* f = fullness_threshold_frac
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*
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* Similarly, we assign zspage to:
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* ZS_ALMOST_FULL when n > N / f
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* ZS_EMPTY when n == 0
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* ZS_FULL when n == N
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*
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* (see: fix_fullness_group())
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*/
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static const int fullness_threshold_frac = 4;
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struct size_class {
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spinlock_t lock;
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struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
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/*
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* Size of objects stored in this class. Must be multiple
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* of ZS_ALIGN.
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*/
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int size;
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unsigned int index;
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/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
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int pages_per_zspage;
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struct zs_size_stat stats;
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/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
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bool huge;
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};
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/*
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* Placed within free objects to form a singly linked list.
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* For every zspage, first_page->freelist gives head of this list.
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*
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* This must be power of 2 and less than or equal to ZS_ALIGN
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*/
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struct link_free {
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union {
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/*
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* Position of next free chunk (encodes <PFN, obj_idx>)
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* It's valid for non-allocated object
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*/
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void *next;
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/*
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* Handle of allocated object.
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*/
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unsigned long handle;
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};
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};
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struct zs_pool {
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const char *name;
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struct size_class **size_class;
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struct kmem_cache *handle_cachep;
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gfp_t flags; /* allocation flags used when growing pool */
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atomic_long_t pages_allocated;
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struct zs_pool_stats stats;
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/* Compact classes */
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struct shrinker shrinker;
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/*
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* To signify that register_shrinker() was successful
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* and unregister_shrinker() will not Oops.
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*/
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bool shrinker_enabled;
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#ifdef CONFIG_ZSMALLOC_STAT
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struct dentry *stat_dentry;
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#endif
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};
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/*
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* A zspage's class index and fullness group
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* are encoded in its (first)page->mapping
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*/
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#define CLASS_IDX_BITS 28
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#define FULLNESS_BITS 4
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#define CLASS_IDX_MASK ((1 << CLASS_IDX_BITS) - 1)
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#define FULLNESS_MASK ((1 << FULLNESS_BITS) - 1)
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struct mapping_area {
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#ifdef CONFIG_PGTABLE_MAPPING
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struct vm_struct *vm; /* vm area for mapping object that span pages */
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#else
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char *vm_buf; /* copy buffer for objects that span pages */
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#endif
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char *vm_addr; /* address of kmap_atomic()'ed pages */
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enum zs_mapmode vm_mm; /* mapping mode */
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bool huge;
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};
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static int create_handle_cache(struct zs_pool *pool)
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{
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pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
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0, 0, NULL);
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return pool->handle_cachep ? 0 : 1;
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}
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static void destroy_handle_cache(struct zs_pool *pool)
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{
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kmem_cache_destroy(pool->handle_cachep);
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}
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static unsigned long alloc_handle(struct zs_pool *pool)
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{
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return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
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pool->flags & ~__GFP_HIGHMEM);
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}
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static void free_handle(struct zs_pool *pool, unsigned long handle)
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{
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kmem_cache_free(pool->handle_cachep, (void *)handle);
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}
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static void record_obj(unsigned long handle, unsigned long obj)
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{
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*(unsigned long *)handle = obj;
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}
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/* zpool driver */
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#ifdef CONFIG_ZPOOL
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static void *zs_zpool_create(const char *name, gfp_t gfp,
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const struct zpool_ops *zpool_ops,
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struct zpool *zpool)
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{
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return zs_create_pool(name, gfp);
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}
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static void zs_zpool_destroy(void *pool)
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{
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zs_destroy_pool(pool);
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}
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static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp,
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unsigned long *handle)
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{
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*handle = zs_malloc(pool, size);
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return *handle ? 0 : -1;
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}
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static void zs_zpool_free(void *pool, unsigned long handle)
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{
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zs_free(pool, handle);
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}
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static int zs_zpool_shrink(void *pool, unsigned int pages,
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unsigned int *reclaimed)
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{
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return -EINVAL;
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}
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static void *zs_zpool_map(void *pool, unsigned long handle,
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enum zpool_mapmode mm)
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{
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enum zs_mapmode zs_mm;
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switch (mm) {
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case ZPOOL_MM_RO:
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zs_mm = ZS_MM_RO;
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break;
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case ZPOOL_MM_WO:
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zs_mm = ZS_MM_WO;
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break;
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case ZPOOL_MM_RW: /* fallthru */
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default:
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zs_mm = ZS_MM_RW;
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break;
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}
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return zs_map_object(pool, handle, zs_mm);
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}
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static void zs_zpool_unmap(void *pool, unsigned long handle)
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{
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zs_unmap_object(pool, handle);
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}
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static u64 zs_zpool_total_size(void *pool)
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{
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return zs_get_total_pages(pool) << PAGE_SHIFT;
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}
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static struct zpool_driver zs_zpool_driver = {
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.type = "zsmalloc",
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.owner = THIS_MODULE,
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.create = zs_zpool_create,
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.destroy = zs_zpool_destroy,
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.malloc = zs_zpool_malloc,
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.free = zs_zpool_free,
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.shrink = zs_zpool_shrink,
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.map = zs_zpool_map,
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.unmap = zs_zpool_unmap,
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.total_size = zs_zpool_total_size,
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};
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MODULE_ALIAS("zpool-zsmalloc");
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#endif /* CONFIG_ZPOOL */
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static unsigned int get_maxobj_per_zspage(int size, int pages_per_zspage)
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{
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return pages_per_zspage * PAGE_SIZE / size;
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}
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/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
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static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
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static int is_first_page(struct page *page)
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{
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return PagePrivate(page);
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}
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static int is_last_page(struct page *page)
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{
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return PagePrivate2(page);
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}
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static void get_zspage_mapping(struct page *page, unsigned int *class_idx,
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enum fullness_group *fullness)
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{
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unsigned long m;
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BUG_ON(!is_first_page(page));
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m = (unsigned long)page->mapping;
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*fullness = m & FULLNESS_MASK;
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*class_idx = (m >> FULLNESS_BITS) & CLASS_IDX_MASK;
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}
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static void set_zspage_mapping(struct page *page, unsigned int class_idx,
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enum fullness_group fullness)
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{
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unsigned long m;
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BUG_ON(!is_first_page(page));
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m = ((class_idx & CLASS_IDX_MASK) << FULLNESS_BITS) |
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(fullness & FULLNESS_MASK);
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page->mapping = (struct address_space *)m;
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}
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/*
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* zsmalloc divides the pool into various size classes where each
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* class maintains a list of zspages where each zspage is divided
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* into equal sized chunks. Each allocation falls into one of these
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* classes depending on its size. This function returns index of the
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* size class which has chunk size big enough to hold the give size.
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*/
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static int get_size_class_index(int size)
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{
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int idx = 0;
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if (likely(size > ZS_MIN_ALLOC_SIZE))
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idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
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ZS_SIZE_CLASS_DELTA);
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return min(zs_size_classes - 1, idx);
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}
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static inline void zs_stat_inc(struct size_class *class,
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enum zs_stat_type type, unsigned long cnt)
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{
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if (type < NR_ZS_STAT_TYPE)
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class->stats.objs[type] += cnt;
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}
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static inline void zs_stat_dec(struct size_class *class,
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enum zs_stat_type type, unsigned long cnt)
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{
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if (type < NR_ZS_STAT_TYPE)
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class->stats.objs[type] -= cnt;
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}
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static inline unsigned long zs_stat_get(struct size_class *class,
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enum zs_stat_type type)
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{
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if (type < NR_ZS_STAT_TYPE)
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return class->stats.objs[type];
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return 0;
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}
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#ifdef CONFIG_ZSMALLOC_STAT
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static int __init zs_stat_init(void)
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{
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if (!debugfs_initialized())
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return -ENODEV;
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zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
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if (!zs_stat_root)
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return -ENOMEM;
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return 0;
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}
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static void __exit zs_stat_exit(void)
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{
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debugfs_remove_recursive(zs_stat_root);
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}
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static int zs_stats_size_show(struct seq_file *s, void *v)
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{
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int i;
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struct zs_pool *pool = s->private;
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struct size_class *class;
|
|
int objs_per_zspage;
|
|
unsigned long class_almost_full, class_almost_empty;
|
|
unsigned long obj_allocated, obj_used, pages_used;
|
|
unsigned long total_class_almost_full = 0, total_class_almost_empty = 0;
|
|
unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
|
|
|
|
seq_printf(s, " %5s %5s %11s %12s %13s %10s %10s %16s\n",
|
|
"class", "size", "almost_full", "almost_empty",
|
|
"obj_allocated", "obj_used", "pages_used",
|
|
"pages_per_zspage");
|
|
|
|
for (i = 0; i < zs_size_classes; i++) {
|
|
class = pool->size_class[i];
|
|
|
|
if (class->index != i)
|
|
continue;
|
|
|
|
spin_lock(&class->lock);
|
|
class_almost_full = zs_stat_get(class, CLASS_ALMOST_FULL);
|
|
class_almost_empty = zs_stat_get(class, CLASS_ALMOST_EMPTY);
|
|
obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
|
|
obj_used = zs_stat_get(class, OBJ_USED);
|
|
spin_unlock(&class->lock);
|
|
|
|
objs_per_zspage = get_maxobj_per_zspage(class->size,
|
|
class->pages_per_zspage);
|
|
pages_used = obj_allocated / objs_per_zspage *
|
|
class->pages_per_zspage;
|
|
|
|
seq_printf(s, " %5u %5u %11lu %12lu %13lu %10lu %10lu %16d\n",
|
|
i, class->size, class_almost_full, class_almost_empty,
|
|
obj_allocated, obj_used, pages_used,
|
|
class->pages_per_zspage);
|
|
|
|
total_class_almost_full += class_almost_full;
|
|
total_class_almost_empty += class_almost_empty;
|
|
total_objs += obj_allocated;
|
|
total_used_objs += obj_used;
|
|
total_pages += pages_used;
|
|
}
|
|
|
|
seq_puts(s, "\n");
|
|
seq_printf(s, " %5s %5s %11lu %12lu %13lu %10lu %10lu\n",
|
|
"Total", "", total_class_almost_full,
|
|
total_class_almost_empty, total_objs,
|
|
total_used_objs, total_pages);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int zs_stats_size_open(struct inode *inode, struct file *file)
|
|
{
|
|
return single_open(file, zs_stats_size_show, inode->i_private);
|
|
}
|
|
|
|
static const struct file_operations zs_stat_size_ops = {
|
|
.open = zs_stats_size_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = single_release,
|
|
};
|
|
|
|
static int zs_pool_stat_create(const char *name, struct zs_pool *pool)
|
|
{
|
|
struct dentry *entry;
|
|
|
|
if (!zs_stat_root)
|
|
return -ENODEV;
|
|
|
|
entry = debugfs_create_dir(name, zs_stat_root);
|
|
if (!entry) {
|
|
pr_warn("debugfs dir <%s> creation failed\n", name);
|
|
return -ENOMEM;
|
|
}
|
|
pool->stat_dentry = entry;
|
|
|
|
entry = debugfs_create_file("classes", S_IFREG | S_IRUGO,
|
|
pool->stat_dentry, pool, &zs_stat_size_ops);
|
|
if (!entry) {
|
|
pr_warn("%s: debugfs file entry <%s> creation failed\n",
|
|
name, "classes");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void zs_pool_stat_destroy(struct zs_pool *pool)
|
|
{
|
|
debugfs_remove_recursive(pool->stat_dentry);
|
|
}
|
|
|
|
#else /* CONFIG_ZSMALLOC_STAT */
|
|
static int __init zs_stat_init(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static void __exit zs_stat_exit(void)
|
|
{
|
|
}
|
|
|
|
static inline int zs_pool_stat_create(const char *name, struct zs_pool *pool)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline void zs_pool_stat_destroy(struct zs_pool *pool)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
|
|
/*
|
|
* For each size class, zspages are divided into different groups
|
|
* depending on how "full" they are. This was done so that we could
|
|
* easily find empty or nearly empty zspages when we try to shrink
|
|
* the pool (not yet implemented). This function returns fullness
|
|
* status of the given page.
|
|
*/
|
|
static enum fullness_group get_fullness_group(struct page *page)
|
|
{
|
|
int inuse, max_objects;
|
|
enum fullness_group fg;
|
|
BUG_ON(!is_first_page(page));
|
|
|
|
inuse = page->inuse;
|
|
max_objects = page->objects;
|
|
|
|
if (inuse == 0)
|
|
fg = ZS_EMPTY;
|
|
else if (inuse == max_objects)
|
|
fg = ZS_FULL;
|
|
else if (inuse <= 3 * max_objects / fullness_threshold_frac)
|
|
fg = ZS_ALMOST_EMPTY;
|
|
else
|
|
fg = ZS_ALMOST_FULL;
|
|
|
|
return fg;
|
|
}
|
|
|
|
/*
|
|
* Each size class maintains various freelists and zspages are assigned
|
|
* to one of these freelists based on the number of live objects they
|
|
* have. This functions inserts the given zspage into the freelist
|
|
* identified by <class, fullness_group>.
|
|
*/
|
|
static void insert_zspage(struct page *page, struct size_class *class,
|
|
enum fullness_group fullness)
|
|
{
|
|
struct page **head;
|
|
|
|
BUG_ON(!is_first_page(page));
|
|
|
|
if (fullness >= _ZS_NR_FULLNESS_GROUPS)
|
|
return;
|
|
|
|
zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ?
|
|
CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
|
|
|
|
head = &class->fullness_list[fullness];
|
|
if (!*head) {
|
|
*head = page;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* We want to see more ZS_FULL pages and less almost
|
|
* empty/full. Put pages with higher ->inuse first.
|
|
*/
|
|
list_add_tail(&page->lru, &(*head)->lru);
|
|
if (page->inuse >= (*head)->inuse)
|
|
*head = page;
|
|
}
|
|
|
|
/*
|
|
* This function removes the given zspage from the freelist identified
|
|
* by <class, fullness_group>.
|
|
*/
|
|
static void remove_zspage(struct page *page, struct size_class *class,
|
|
enum fullness_group fullness)
|
|
{
|
|
struct page **head;
|
|
|
|
BUG_ON(!is_first_page(page));
|
|
|
|
if (fullness >= _ZS_NR_FULLNESS_GROUPS)
|
|
return;
|
|
|
|
head = &class->fullness_list[fullness];
|
|
BUG_ON(!*head);
|
|
if (list_empty(&(*head)->lru))
|
|
*head = NULL;
|
|
else if (*head == page)
|
|
*head = (struct page *)list_entry((*head)->lru.next,
|
|
struct page, lru);
|
|
|
|
list_del_init(&page->lru);
|
|
zs_stat_dec(class, fullness == ZS_ALMOST_EMPTY ?
|
|
CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
|
|
}
|
|
|
|
/*
|
|
* Each size class maintains zspages in different fullness groups depending
|
|
* on the number of live objects they contain. When allocating or freeing
|
|
* objects, the fullness status of the page can change, say, from ALMOST_FULL
|
|
* to ALMOST_EMPTY when freeing an object. This function checks if such
|
|
* a status change has occurred for the given page and accordingly moves the
|
|
* page from the freelist of the old fullness group to that of the new
|
|
* fullness group.
|
|
*/
|
|
static enum fullness_group fix_fullness_group(struct size_class *class,
|
|
struct page *page)
|
|
{
|
|
int class_idx;
|
|
enum fullness_group currfg, newfg;
|
|
|
|
BUG_ON(!is_first_page(page));
|
|
|
|
get_zspage_mapping(page, &class_idx, &currfg);
|
|
newfg = get_fullness_group(page);
|
|
if (newfg == currfg)
|
|
goto out;
|
|
|
|
remove_zspage(page, class, currfg);
|
|
insert_zspage(page, class, newfg);
|
|
set_zspage_mapping(page, class_idx, newfg);
|
|
|
|
out:
|
|
return newfg;
|
|
}
|
|
|
|
/*
|
|
* We have to decide on how many pages to link together
|
|
* to form a zspage for each size class. This is important
|
|
* to reduce wastage due to unusable space left at end of
|
|
* each zspage which is given as:
|
|
* wastage = Zp % class_size
|
|
* usage = Zp - wastage
|
|
* where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
|
|
*
|
|
* For example, for size class of 3/8 * PAGE_SIZE, we should
|
|
* link together 3 PAGE_SIZE sized pages to form a zspage
|
|
* since then we can perfectly fit in 8 such objects.
|
|
*/
|
|
static int get_pages_per_zspage(int class_size)
|
|
{
|
|
int i, max_usedpc = 0;
|
|
/* zspage order which gives maximum used size per KB */
|
|
int max_usedpc_order = 1;
|
|
|
|
for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
|
|
int zspage_size;
|
|
int waste, usedpc;
|
|
|
|
zspage_size = i * PAGE_SIZE;
|
|
waste = zspage_size % class_size;
|
|
usedpc = (zspage_size - waste) * 100 / zspage_size;
|
|
|
|
if (usedpc > max_usedpc) {
|
|
max_usedpc = usedpc;
|
|
max_usedpc_order = i;
|
|
}
|
|
}
|
|
|
|
return max_usedpc_order;
|
|
}
|
|
|
|
/*
|
|
* A single 'zspage' is composed of many system pages which are
|
|
* linked together using fields in struct page. This function finds
|
|
* the first/head page, given any component page of a zspage.
|
|
*/
|
|
static struct page *get_first_page(struct page *page)
|
|
{
|
|
if (is_first_page(page))
|
|
return page;
|
|
else
|
|
return (struct page *)page_private(page);
|
|
}
|
|
|
|
static struct page *get_next_page(struct page *page)
|
|
{
|
|
struct page *next;
|
|
|
|
if (is_last_page(page))
|
|
next = NULL;
|
|
else if (is_first_page(page))
|
|
next = (struct page *)page_private(page);
|
|
else
|
|
next = list_entry(page->lru.next, struct page, lru);
|
|
|
|
return next;
|
|
}
|
|
|
|
/*
|
|
* Encode <page, obj_idx> as a single handle value.
|
|
* We use the least bit of handle for tagging.
|
|
*/
|
|
static void *location_to_obj(struct page *page, unsigned long obj_idx)
|
|
{
|
|
unsigned long obj;
|
|
|
|
if (!page) {
|
|
BUG_ON(obj_idx);
|
|
return NULL;
|
|
}
|
|
|
|
obj = page_to_pfn(page) << OBJ_INDEX_BITS;
|
|
obj |= ((obj_idx) & OBJ_INDEX_MASK);
|
|
obj <<= OBJ_TAG_BITS;
|
|
|
|
return (void *)obj;
|
|
}
|
|
|
|
/*
|
|
* Decode <page, obj_idx> pair from the given object handle. We adjust the
|
|
* decoded obj_idx back to its original value since it was adjusted in
|
|
* location_to_obj().
|
|
*/
|
|
static void obj_to_location(unsigned long obj, struct page **page,
|
|
unsigned long *obj_idx)
|
|
{
|
|
obj >>= OBJ_TAG_BITS;
|
|
*page = pfn_to_page(obj >> OBJ_INDEX_BITS);
|
|
*obj_idx = (obj & OBJ_INDEX_MASK);
|
|
}
|
|
|
|
static unsigned long handle_to_obj(unsigned long handle)
|
|
{
|
|
return *(unsigned long *)handle;
|
|
}
|
|
|
|
static unsigned long obj_to_head(struct size_class *class, struct page *page,
|
|
void *obj)
|
|
{
|
|
if (class->huge) {
|
|
VM_BUG_ON(!is_first_page(page));
|
|
return page_private(page);
|
|
} else
|
|
return *(unsigned long *)obj;
|
|
}
|
|
|
|
static unsigned long obj_idx_to_offset(struct page *page,
|
|
unsigned long obj_idx, int class_size)
|
|
{
|
|
unsigned long off = 0;
|
|
|
|
if (!is_first_page(page))
|
|
off = page->index;
|
|
|
|
return off + obj_idx * class_size;
|
|
}
|
|
|
|
static inline int trypin_tag(unsigned long handle)
|
|
{
|
|
unsigned long *ptr = (unsigned long *)handle;
|
|
|
|
return !test_and_set_bit_lock(HANDLE_PIN_BIT, ptr);
|
|
}
|
|
|
|
static void pin_tag(unsigned long handle)
|
|
{
|
|
while (!trypin_tag(handle));
|
|
}
|
|
|
|
static void unpin_tag(unsigned long handle)
|
|
{
|
|
unsigned long *ptr = (unsigned long *)handle;
|
|
|
|
clear_bit_unlock(HANDLE_PIN_BIT, ptr);
|
|
}
|
|
|
|
static void reset_page(struct page *page)
|
|
{
|
|
clear_bit(PG_private, &page->flags);
|
|
clear_bit(PG_private_2, &page->flags);
|
|
set_page_private(page, 0);
|
|
page->mapping = NULL;
|
|
page->freelist = NULL;
|
|
page_mapcount_reset(page);
|
|
}
|
|
|
|
static void free_zspage(struct page *first_page)
|
|
{
|
|
struct page *nextp, *tmp, *head_extra;
|
|
|
|
BUG_ON(!is_first_page(first_page));
|
|
BUG_ON(first_page->inuse);
|
|
|
|
head_extra = (struct page *)page_private(first_page);
|
|
|
|
reset_page(first_page);
|
|
__free_page(first_page);
|
|
|
|
/* zspage with only 1 system page */
|
|
if (!head_extra)
|
|
return;
|
|
|
|
list_for_each_entry_safe(nextp, tmp, &head_extra->lru, lru) {
|
|
list_del(&nextp->lru);
|
|
reset_page(nextp);
|
|
__free_page(nextp);
|
|
}
|
|
reset_page(head_extra);
|
|
__free_page(head_extra);
|
|
}
|
|
|
|
/* Initialize a newly allocated zspage */
|
|
static void init_zspage(struct page *first_page, struct size_class *class)
|
|
{
|
|
unsigned long off = 0;
|
|
struct page *page = first_page;
|
|
|
|
BUG_ON(!is_first_page(first_page));
|
|
while (page) {
|
|
struct page *next_page;
|
|
struct link_free *link;
|
|
unsigned int i = 1;
|
|
void *vaddr;
|
|
|
|
/*
|
|
* page->index stores offset of first object starting
|
|
* in the page. For the first page, this is always 0,
|
|
* so we use first_page->index (aka ->freelist) to store
|
|
* head of corresponding zspage's freelist.
|
|
*/
|
|
if (page != first_page)
|
|
page->index = off;
|
|
|
|
vaddr = kmap_atomic(page);
|
|
link = (struct link_free *)vaddr + off / sizeof(*link);
|
|
|
|
while ((off += class->size) < PAGE_SIZE) {
|
|
link->next = location_to_obj(page, i++);
|
|
link += class->size / sizeof(*link);
|
|
}
|
|
|
|
/*
|
|
* We now come to the last (full or partial) object on this
|
|
* page, which must point to the first object on the next
|
|
* page (if present)
|
|
*/
|
|
next_page = get_next_page(page);
|
|
link->next = location_to_obj(next_page, 0);
|
|
kunmap_atomic(vaddr);
|
|
page = next_page;
|
|
off %= PAGE_SIZE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate a zspage for the given size class
|
|
*/
|
|
static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
|
|
{
|
|
int i, error;
|
|
struct page *first_page = NULL, *uninitialized_var(prev_page);
|
|
|
|
/*
|
|
* Allocate individual pages and link them together as:
|
|
* 1. first page->private = first sub-page
|
|
* 2. all sub-pages are linked together using page->lru
|
|
* 3. each sub-page is linked to the first page using page->private
|
|
*
|
|
* For each size class, First/Head pages are linked together using
|
|
* page->lru. Also, we set PG_private to identify the first page
|
|
* (i.e. no other sub-page has this flag set) and PG_private_2 to
|
|
* identify the last page.
|
|
*/
|
|
error = -ENOMEM;
|
|
for (i = 0; i < class->pages_per_zspage; i++) {
|
|
struct page *page;
|
|
|
|
page = alloc_page(flags);
|
|
if (!page)
|
|
goto cleanup;
|
|
|
|
INIT_LIST_HEAD(&page->lru);
|
|
if (i == 0) { /* first page */
|
|
SetPagePrivate(page);
|
|
set_page_private(page, 0);
|
|
first_page = page;
|
|
first_page->inuse = 0;
|
|
}
|
|
if (i == 1)
|
|
set_page_private(first_page, (unsigned long)page);
|
|
if (i >= 1)
|
|
set_page_private(page, (unsigned long)first_page);
|
|
if (i >= 2)
|
|
list_add(&page->lru, &prev_page->lru);
|
|
if (i == class->pages_per_zspage - 1) /* last page */
|
|
SetPagePrivate2(page);
|
|
prev_page = page;
|
|
}
|
|
|
|
init_zspage(first_page, class);
|
|
|
|
first_page->freelist = location_to_obj(first_page, 0);
|
|
/* Maximum number of objects we can store in this zspage */
|
|
first_page->objects = class->pages_per_zspage * PAGE_SIZE / class->size;
|
|
|
|
error = 0; /* Success */
|
|
|
|
cleanup:
|
|
if (unlikely(error) && first_page) {
|
|
free_zspage(first_page);
|
|
first_page = NULL;
|
|
}
|
|
|
|
return first_page;
|
|
}
|
|
|
|
static struct page *find_get_zspage(struct size_class *class)
|
|
{
|
|
int i;
|
|
struct page *page;
|
|
|
|
for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
|
|
page = class->fullness_list[i];
|
|
if (page)
|
|
break;
|
|
}
|
|
|
|
return page;
|
|
}
|
|
|
|
#ifdef CONFIG_PGTABLE_MAPPING
|
|
static inline int __zs_cpu_up(struct mapping_area *area)
|
|
{
|
|
/*
|
|
* Make sure we don't leak memory if a cpu UP notification
|
|
* and zs_init() race and both call zs_cpu_up() on the same cpu
|
|
*/
|
|
if (area->vm)
|
|
return 0;
|
|
area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
|
|
if (!area->vm)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static inline void __zs_cpu_down(struct mapping_area *area)
|
|
{
|
|
if (area->vm)
|
|
free_vm_area(area->vm);
|
|
area->vm = NULL;
|
|
}
|
|
|
|
static inline void *__zs_map_object(struct mapping_area *area,
|
|
struct page *pages[2], int off, int size)
|
|
{
|
|
BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, pages));
|
|
area->vm_addr = area->vm->addr;
|
|
return area->vm_addr + off;
|
|
}
|
|
|
|
static inline void __zs_unmap_object(struct mapping_area *area,
|
|
struct page *pages[2], int off, int size)
|
|
{
|
|
unsigned long addr = (unsigned long)area->vm_addr;
|
|
|
|
unmap_kernel_range(addr, PAGE_SIZE * 2);
|
|
}
|
|
|
|
#else /* CONFIG_PGTABLE_MAPPING */
|
|
|
|
static inline int __zs_cpu_up(struct mapping_area *area)
|
|
{
|
|
/*
|
|
* Make sure we don't leak memory if a cpu UP notification
|
|
* and zs_init() race and both call zs_cpu_up() on the same cpu
|
|
*/
|
|
if (area->vm_buf)
|
|
return 0;
|
|
area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL);
|
|
if (!area->vm_buf)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static inline void __zs_cpu_down(struct mapping_area *area)
|
|
{
|
|
kfree(area->vm_buf);
|
|
area->vm_buf = NULL;
|
|
}
|
|
|
|
static void *__zs_map_object(struct mapping_area *area,
|
|
struct page *pages[2], int off, int size)
|
|
{
|
|
int sizes[2];
|
|
void *addr;
|
|
char *buf = area->vm_buf;
|
|
|
|
/* disable page faults to match kmap_atomic() return conditions */
|
|
pagefault_disable();
|
|
|
|
/* no read fastpath */
|
|
if (area->vm_mm == ZS_MM_WO)
|
|
goto out;
|
|
|
|
sizes[0] = PAGE_SIZE - off;
|
|
sizes[1] = size - sizes[0];
|
|
|
|
/* copy object to per-cpu buffer */
|
|
addr = kmap_atomic(pages[0]);
|
|
memcpy(buf, addr + off, sizes[0]);
|
|
kunmap_atomic(addr);
|
|
addr = kmap_atomic(pages[1]);
|
|
memcpy(buf + sizes[0], addr, sizes[1]);
|
|
kunmap_atomic(addr);
|
|
out:
|
|
return area->vm_buf;
|
|
}
|
|
|
|
static void __zs_unmap_object(struct mapping_area *area,
|
|
struct page *pages[2], int off, int size)
|
|
{
|
|
int sizes[2];
|
|
void *addr;
|
|
char *buf;
|
|
|
|
/* no write fastpath */
|
|
if (area->vm_mm == ZS_MM_RO)
|
|
goto out;
|
|
|
|
buf = area->vm_buf;
|
|
if (!area->huge) {
|
|
buf = buf + ZS_HANDLE_SIZE;
|
|
size -= ZS_HANDLE_SIZE;
|
|
off += ZS_HANDLE_SIZE;
|
|
}
|
|
|
|
sizes[0] = PAGE_SIZE - off;
|
|
sizes[1] = size - sizes[0];
|
|
|
|
/* copy per-cpu buffer to object */
|
|
addr = kmap_atomic(pages[0]);
|
|
memcpy(addr + off, buf, sizes[0]);
|
|
kunmap_atomic(addr);
|
|
addr = kmap_atomic(pages[1]);
|
|
memcpy(addr, buf + sizes[0], sizes[1]);
|
|
kunmap_atomic(addr);
|
|
|
|
out:
|
|
/* enable page faults to match kunmap_atomic() return conditions */
|
|
pagefault_enable();
|
|
}
|
|
|
|
#endif /* CONFIG_PGTABLE_MAPPING */
|
|
|
|
static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
|
|
void *pcpu)
|
|
{
|
|
int ret, cpu = (long)pcpu;
|
|
struct mapping_area *area;
|
|
|
|
switch (action) {
|
|
case CPU_UP_PREPARE:
|
|
area = &per_cpu(zs_map_area, cpu);
|
|
ret = __zs_cpu_up(area);
|
|
if (ret)
|
|
return notifier_from_errno(ret);
|
|
break;
|
|
case CPU_DEAD:
|
|
case CPU_UP_CANCELED:
|
|
area = &per_cpu(zs_map_area, cpu);
|
|
__zs_cpu_down(area);
|
|
break;
|
|
}
|
|
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block zs_cpu_nb = {
|
|
.notifier_call = zs_cpu_notifier
|
|
};
|
|
|
|
static int zs_register_cpu_notifier(void)
|
|
{
|
|
int cpu, uninitialized_var(ret);
|
|
|
|
cpu_notifier_register_begin();
|
|
|
|
__register_cpu_notifier(&zs_cpu_nb);
|
|
for_each_online_cpu(cpu) {
|
|
ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
|
|
if (notifier_to_errno(ret))
|
|
break;
|
|
}
|
|
|
|
cpu_notifier_register_done();
|
|
return notifier_to_errno(ret);
|
|
}
|
|
|
|
static void zs_unregister_cpu_notifier(void)
|
|
{
|
|
int cpu;
|
|
|
|
cpu_notifier_register_begin();
|
|
|
|
for_each_online_cpu(cpu)
|
|
zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
|
|
__unregister_cpu_notifier(&zs_cpu_nb);
|
|
|
|
cpu_notifier_register_done();
|
|
}
|
|
|
|
static void init_zs_size_classes(void)
|
|
{
|
|
int nr;
|
|
|
|
nr = (ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / ZS_SIZE_CLASS_DELTA + 1;
|
|
if ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) % ZS_SIZE_CLASS_DELTA)
|
|
nr += 1;
|
|
|
|
zs_size_classes = nr;
|
|
}
|
|
|
|
static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
|
|
{
|
|
if (prev->pages_per_zspage != pages_per_zspage)
|
|
return false;
|
|
|
|
if (get_maxobj_per_zspage(prev->size, prev->pages_per_zspage)
|
|
!= get_maxobj_per_zspage(size, pages_per_zspage))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool zspage_full(struct page *page)
|
|
{
|
|
BUG_ON(!is_first_page(page));
|
|
|
|
return page->inuse == page->objects;
|
|
}
|
|
|
|
unsigned long zs_get_total_pages(struct zs_pool *pool)
|
|
{
|
|
return atomic_long_read(&pool->pages_allocated);
|
|
}
|
|
EXPORT_SYMBOL_GPL(zs_get_total_pages);
|
|
|
|
/**
|
|
* zs_map_object - get address of allocated object from handle.
|
|
* @pool: pool from which the object was allocated
|
|
* @handle: handle returned from zs_malloc
|
|
*
|
|
* Before using an object allocated from zs_malloc, it must be mapped using
|
|
* this function. When done with the object, it must be unmapped using
|
|
* zs_unmap_object.
|
|
*
|
|
* Only one object can be mapped per cpu at a time. There is no protection
|
|
* against nested mappings.
|
|
*
|
|
* This function returns with preemption and page faults disabled.
|
|
*/
|
|
void *zs_map_object(struct zs_pool *pool, unsigned long handle,
|
|
enum zs_mapmode mm)
|
|
{
|
|
struct page *page;
|
|
unsigned long obj, obj_idx, off;
|
|
|
|
unsigned int class_idx;
|
|
enum fullness_group fg;
|
|
struct size_class *class;
|
|
struct mapping_area *area;
|
|
struct page *pages[2];
|
|
void *ret;
|
|
|
|
BUG_ON(!handle);
|
|
|
|
/*
|
|
* Because we use per-cpu mapping areas shared among the
|
|
* pools/users, we can't allow mapping in interrupt context
|
|
* because it can corrupt another users mappings.
|
|
*/
|
|
BUG_ON(in_interrupt());
|
|
|
|
/* From now on, migration cannot move the object */
|
|
pin_tag(handle);
|
|
|
|
obj = handle_to_obj(handle);
|
|
obj_to_location(obj, &page, &obj_idx);
|
|
get_zspage_mapping(get_first_page(page), &class_idx, &fg);
|
|
class = pool->size_class[class_idx];
|
|
off = obj_idx_to_offset(page, obj_idx, class->size);
|
|
|
|
area = &get_cpu_var(zs_map_area);
|
|
area->vm_mm = mm;
|
|
if (off + class->size <= PAGE_SIZE) {
|
|
/* this object is contained entirely within a page */
|
|
area->vm_addr = kmap_atomic(page);
|
|
ret = area->vm_addr + off;
|
|
goto out;
|
|
}
|
|
|
|
/* this object spans two pages */
|
|
pages[0] = page;
|
|
pages[1] = get_next_page(page);
|
|
BUG_ON(!pages[1]);
|
|
|
|
ret = __zs_map_object(area, pages, off, class->size);
|
|
out:
|
|
if (!class->huge)
|
|
ret += ZS_HANDLE_SIZE;
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(zs_map_object);
|
|
|
|
void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
|
|
{
|
|
struct page *page;
|
|
unsigned long obj, obj_idx, off;
|
|
|
|
unsigned int class_idx;
|
|
enum fullness_group fg;
|
|
struct size_class *class;
|
|
struct mapping_area *area;
|
|
|
|
BUG_ON(!handle);
|
|
|
|
obj = handle_to_obj(handle);
|
|
obj_to_location(obj, &page, &obj_idx);
|
|
get_zspage_mapping(get_first_page(page), &class_idx, &fg);
|
|
class = pool->size_class[class_idx];
|
|
off = obj_idx_to_offset(page, obj_idx, class->size);
|
|
|
|
area = this_cpu_ptr(&zs_map_area);
|
|
if (off + class->size <= PAGE_SIZE)
|
|
kunmap_atomic(area->vm_addr);
|
|
else {
|
|
struct page *pages[2];
|
|
|
|
pages[0] = page;
|
|
pages[1] = get_next_page(page);
|
|
BUG_ON(!pages[1]);
|
|
|
|
__zs_unmap_object(area, pages, off, class->size);
|
|
}
|
|
put_cpu_var(zs_map_area);
|
|
unpin_tag(handle);
|
|
}
|
|
EXPORT_SYMBOL_GPL(zs_unmap_object);
|
|
|
|
static unsigned long obj_malloc(struct page *first_page,
|
|
struct size_class *class, unsigned long handle)
|
|
{
|
|
unsigned long obj;
|
|
struct link_free *link;
|
|
|
|
struct page *m_page;
|
|
unsigned long m_objidx, m_offset;
|
|
void *vaddr;
|
|
|
|
handle |= OBJ_ALLOCATED_TAG;
|
|
obj = (unsigned long)first_page->freelist;
|
|
obj_to_location(obj, &m_page, &m_objidx);
|
|
m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
|
|
|
|
vaddr = kmap_atomic(m_page);
|
|
link = (struct link_free *)vaddr + m_offset / sizeof(*link);
|
|
first_page->freelist = link->next;
|
|
if (!class->huge)
|
|
/* record handle in the header of allocated chunk */
|
|
link->handle = handle;
|
|
else
|
|
/* record handle in first_page->private */
|
|
set_page_private(first_page, handle);
|
|
kunmap_atomic(vaddr);
|
|
first_page->inuse++;
|
|
zs_stat_inc(class, OBJ_USED, 1);
|
|
|
|
return obj;
|
|
}
|
|
|
|
|
|
/**
|
|
* zs_malloc - Allocate block of given size from pool.
|
|
* @pool: pool to allocate from
|
|
* @size: size of block to allocate
|
|
*
|
|
* On success, handle to the allocated object is returned,
|
|
* otherwise 0.
|
|
* Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
|
|
*/
|
|
unsigned long zs_malloc(struct zs_pool *pool, size_t size)
|
|
{
|
|
unsigned long handle, obj;
|
|
struct size_class *class;
|
|
struct page *first_page;
|
|
|
|
if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
|
|
return 0;
|
|
|
|
handle = alloc_handle(pool);
|
|
if (!handle)
|
|
return 0;
|
|
|
|
/* extra space in chunk to keep the handle */
|
|
size += ZS_HANDLE_SIZE;
|
|
class = pool->size_class[get_size_class_index(size)];
|
|
|
|
spin_lock(&class->lock);
|
|
first_page = find_get_zspage(class);
|
|
|
|
if (!first_page) {
|
|
spin_unlock(&class->lock);
|
|
first_page = alloc_zspage(class, pool->flags);
|
|
if (unlikely(!first_page)) {
|
|
free_handle(pool, handle);
|
|
return 0;
|
|
}
|
|
|
|
set_zspage_mapping(first_page, class->index, ZS_EMPTY);
|
|
atomic_long_add(class->pages_per_zspage,
|
|
&pool->pages_allocated);
|
|
|
|
spin_lock(&class->lock);
|
|
zs_stat_inc(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
|
|
class->size, class->pages_per_zspage));
|
|
}
|
|
|
|
obj = obj_malloc(first_page, class, handle);
|
|
/* Now move the zspage to another fullness group, if required */
|
|
fix_fullness_group(class, first_page);
|
|
record_obj(handle, obj);
|
|
spin_unlock(&class->lock);
|
|
|
|
return handle;
|
|
}
|
|
EXPORT_SYMBOL_GPL(zs_malloc);
|
|
|
|
static void obj_free(struct zs_pool *pool, struct size_class *class,
|
|
unsigned long obj)
|
|
{
|
|
struct link_free *link;
|
|
struct page *first_page, *f_page;
|
|
unsigned long f_objidx, f_offset;
|
|
void *vaddr;
|
|
|
|
BUG_ON(!obj);
|
|
|
|
obj &= ~OBJ_ALLOCATED_TAG;
|
|
obj_to_location(obj, &f_page, &f_objidx);
|
|
first_page = get_first_page(f_page);
|
|
|
|
f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
|
|
|
|
vaddr = kmap_atomic(f_page);
|
|
|
|
/* Insert this object in containing zspage's freelist */
|
|
link = (struct link_free *)(vaddr + f_offset);
|
|
link->next = first_page->freelist;
|
|
if (class->huge)
|
|
set_page_private(first_page, 0);
|
|
kunmap_atomic(vaddr);
|
|
first_page->freelist = (void *)obj;
|
|
first_page->inuse--;
|
|
zs_stat_dec(class, OBJ_USED, 1);
|
|
}
|
|
|
|
void zs_free(struct zs_pool *pool, unsigned long handle)
|
|
{
|
|
struct page *first_page, *f_page;
|
|
unsigned long obj, f_objidx;
|
|
int class_idx;
|
|
struct size_class *class;
|
|
enum fullness_group fullness;
|
|
|
|
if (unlikely(!handle))
|
|
return;
|
|
|
|
pin_tag(handle);
|
|
obj = handle_to_obj(handle);
|
|
obj_to_location(obj, &f_page, &f_objidx);
|
|
first_page = get_first_page(f_page);
|
|
|
|
get_zspage_mapping(first_page, &class_idx, &fullness);
|
|
class = pool->size_class[class_idx];
|
|
|
|
spin_lock(&class->lock);
|
|
obj_free(pool, class, obj);
|
|
fullness = fix_fullness_group(class, first_page);
|
|
if (fullness == ZS_EMPTY) {
|
|
zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
|
|
class->size, class->pages_per_zspage));
|
|
atomic_long_sub(class->pages_per_zspage,
|
|
&pool->pages_allocated);
|
|
free_zspage(first_page);
|
|
}
|
|
spin_unlock(&class->lock);
|
|
unpin_tag(handle);
|
|
|
|
free_handle(pool, handle);
|
|
}
|
|
EXPORT_SYMBOL_GPL(zs_free);
|
|
|
|
static void zs_object_copy(unsigned long dst, unsigned long src,
|
|
struct size_class *class)
|
|
{
|
|
struct page *s_page, *d_page;
|
|
unsigned long s_objidx, d_objidx;
|
|
unsigned long s_off, d_off;
|
|
void *s_addr, *d_addr;
|
|
int s_size, d_size, size;
|
|
int written = 0;
|
|
|
|
s_size = d_size = class->size;
|
|
|
|
obj_to_location(src, &s_page, &s_objidx);
|
|
obj_to_location(dst, &d_page, &d_objidx);
|
|
|
|
s_off = obj_idx_to_offset(s_page, s_objidx, class->size);
|
|
d_off = obj_idx_to_offset(d_page, d_objidx, class->size);
|
|
|
|
if (s_off + class->size > PAGE_SIZE)
|
|
s_size = PAGE_SIZE - s_off;
|
|
|
|
if (d_off + class->size > PAGE_SIZE)
|
|
d_size = PAGE_SIZE - d_off;
|
|
|
|
s_addr = kmap_atomic(s_page);
|
|
d_addr = kmap_atomic(d_page);
|
|
|
|
while (1) {
|
|
size = min(s_size, d_size);
|
|
memcpy(d_addr + d_off, s_addr + s_off, size);
|
|
written += size;
|
|
|
|
if (written == class->size)
|
|
break;
|
|
|
|
s_off += size;
|
|
s_size -= size;
|
|
d_off += size;
|
|
d_size -= size;
|
|
|
|
if (s_off >= PAGE_SIZE) {
|
|
kunmap_atomic(d_addr);
|
|
kunmap_atomic(s_addr);
|
|
s_page = get_next_page(s_page);
|
|
BUG_ON(!s_page);
|
|
s_addr = kmap_atomic(s_page);
|
|
d_addr = kmap_atomic(d_page);
|
|
s_size = class->size - written;
|
|
s_off = 0;
|
|
}
|
|
|
|
if (d_off >= PAGE_SIZE) {
|
|
kunmap_atomic(d_addr);
|
|
d_page = get_next_page(d_page);
|
|
BUG_ON(!d_page);
|
|
d_addr = kmap_atomic(d_page);
|
|
d_size = class->size - written;
|
|
d_off = 0;
|
|
}
|
|
}
|
|
|
|
kunmap_atomic(d_addr);
|
|
kunmap_atomic(s_addr);
|
|
}
|
|
|
|
/*
|
|
* Find alloced object in zspage from index object and
|
|
* return handle.
|
|
*/
|
|
static unsigned long find_alloced_obj(struct page *page, int index,
|
|
struct size_class *class)
|
|
{
|
|
unsigned long head;
|
|
int offset = 0;
|
|
unsigned long handle = 0;
|
|
void *addr = kmap_atomic(page);
|
|
|
|
if (!is_first_page(page))
|
|
offset = page->index;
|
|
offset += class->size * index;
|
|
|
|
while (offset < PAGE_SIZE) {
|
|
head = obj_to_head(class, page, addr + offset);
|
|
if (head & OBJ_ALLOCATED_TAG) {
|
|
handle = head & ~OBJ_ALLOCATED_TAG;
|
|
if (trypin_tag(handle))
|
|
break;
|
|
handle = 0;
|
|
}
|
|
|
|
offset += class->size;
|
|
index++;
|
|
}
|
|
|
|
kunmap_atomic(addr);
|
|
return handle;
|
|
}
|
|
|
|
struct zs_compact_control {
|
|
/* Source page for migration which could be a subpage of zspage. */
|
|
struct page *s_page;
|
|
/* Destination page for migration which should be a first page
|
|
* of zspage. */
|
|
struct page *d_page;
|
|
/* Starting object index within @s_page which used for live object
|
|
* in the subpage. */
|
|
int index;
|
|
};
|
|
|
|
static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
|
|
struct zs_compact_control *cc)
|
|
{
|
|
unsigned long used_obj, free_obj;
|
|
unsigned long handle;
|
|
struct page *s_page = cc->s_page;
|
|
struct page *d_page = cc->d_page;
|
|
unsigned long index = cc->index;
|
|
int ret = 0;
|
|
|
|
while (1) {
|
|
handle = find_alloced_obj(s_page, index, class);
|
|
if (!handle) {
|
|
s_page = get_next_page(s_page);
|
|
if (!s_page)
|
|
break;
|
|
index = 0;
|
|
continue;
|
|
}
|
|
|
|
/* Stop if there is no more space */
|
|
if (zspage_full(d_page)) {
|
|
unpin_tag(handle);
|
|
ret = -ENOMEM;
|
|
break;
|
|
}
|
|
|
|
used_obj = handle_to_obj(handle);
|
|
free_obj = obj_malloc(d_page, class, handle);
|
|
zs_object_copy(free_obj, used_obj, class);
|
|
index++;
|
|
record_obj(handle, free_obj);
|
|
unpin_tag(handle);
|
|
obj_free(pool, class, used_obj);
|
|
}
|
|
|
|
/* Remember last position in this iteration */
|
|
cc->s_page = s_page;
|
|
cc->index = index;
|
|
|
|
return ret;
|
|
}
|
|
|
|
static struct page *isolate_target_page(struct size_class *class)
|
|
{
|
|
int i;
|
|
struct page *page;
|
|
|
|
for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
|
|
page = class->fullness_list[i];
|
|
if (page) {
|
|
remove_zspage(page, class, i);
|
|
break;
|
|
}
|
|
}
|
|
|
|
return page;
|
|
}
|
|
|
|
/*
|
|
* putback_zspage - add @first_page into right class's fullness list
|
|
* @pool: target pool
|
|
* @class: destination class
|
|
* @first_page: target page
|
|
*
|
|
* Return @fist_page's fullness_group
|
|
*/
|
|
static enum fullness_group putback_zspage(struct zs_pool *pool,
|
|
struct size_class *class,
|
|
struct page *first_page)
|
|
{
|
|
enum fullness_group fullness;
|
|
|
|
BUG_ON(!is_first_page(first_page));
|
|
|
|
fullness = get_fullness_group(first_page);
|
|
insert_zspage(first_page, class, fullness);
|
|
set_zspage_mapping(first_page, class->index, fullness);
|
|
|
|
if (fullness == ZS_EMPTY) {
|
|
zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
|
|
class->size, class->pages_per_zspage));
|
|
atomic_long_sub(class->pages_per_zspage,
|
|
&pool->pages_allocated);
|
|
|
|
free_zspage(first_page);
|
|
}
|
|
|
|
return fullness;
|
|
}
|
|
|
|
static struct page *isolate_source_page(struct size_class *class)
|
|
{
|
|
int i;
|
|
struct page *page = NULL;
|
|
|
|
for (i = ZS_ALMOST_EMPTY; i >= ZS_ALMOST_FULL; i--) {
|
|
page = class->fullness_list[i];
|
|
if (!page)
|
|
continue;
|
|
|
|
remove_zspage(page, class, i);
|
|
break;
|
|
}
|
|
|
|
return page;
|
|
}
|
|
|
|
/*
|
|
*
|
|
* Based on the number of unused allocated objects calculate
|
|
* and return the number of pages that we can free.
|
|
*/
|
|
static unsigned long zs_can_compact(struct size_class *class)
|
|
{
|
|
unsigned long obj_wasted;
|
|
|
|
obj_wasted = zs_stat_get(class, OBJ_ALLOCATED) -
|
|
zs_stat_get(class, OBJ_USED);
|
|
|
|
obj_wasted /= get_maxobj_per_zspage(class->size,
|
|
class->pages_per_zspage);
|
|
|
|
return obj_wasted * class->pages_per_zspage;
|
|
}
|
|
|
|
static void __zs_compact(struct zs_pool *pool, struct size_class *class)
|
|
{
|
|
struct zs_compact_control cc;
|
|
struct page *src_page;
|
|
struct page *dst_page = NULL;
|
|
|
|
spin_lock(&class->lock);
|
|
while ((src_page = isolate_source_page(class))) {
|
|
|
|
BUG_ON(!is_first_page(src_page));
|
|
|
|
if (!zs_can_compact(class))
|
|
break;
|
|
|
|
cc.index = 0;
|
|
cc.s_page = src_page;
|
|
|
|
while ((dst_page = isolate_target_page(class))) {
|
|
cc.d_page = dst_page;
|
|
/*
|
|
* If there is no more space in dst_page, resched
|
|
* and see if anyone had allocated another zspage.
|
|
*/
|
|
if (!migrate_zspage(pool, class, &cc))
|
|
break;
|
|
|
|
putback_zspage(pool, class, dst_page);
|
|
}
|
|
|
|
/* Stop if we couldn't find slot */
|
|
if (dst_page == NULL)
|
|
break;
|
|
|
|
putback_zspage(pool, class, dst_page);
|
|
if (putback_zspage(pool, class, src_page) == ZS_EMPTY)
|
|
pool->stats.pages_compacted += class->pages_per_zspage;
|
|
spin_unlock(&class->lock);
|
|
cond_resched();
|
|
spin_lock(&class->lock);
|
|
}
|
|
|
|
if (src_page)
|
|
putback_zspage(pool, class, src_page);
|
|
|
|
spin_unlock(&class->lock);
|
|
}
|
|
|
|
unsigned long zs_compact(struct zs_pool *pool)
|
|
{
|
|
int i;
|
|
struct size_class *class;
|
|
|
|
for (i = zs_size_classes - 1; i >= 0; i--) {
|
|
class = pool->size_class[i];
|
|
if (!class)
|
|
continue;
|
|
if (class->index != i)
|
|
continue;
|
|
__zs_compact(pool, class);
|
|
}
|
|
|
|
return pool->stats.pages_compacted;
|
|
}
|
|
EXPORT_SYMBOL_GPL(zs_compact);
|
|
|
|
void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats)
|
|
{
|
|
memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats));
|
|
}
|
|
EXPORT_SYMBOL_GPL(zs_pool_stats);
|
|
|
|
static unsigned long zs_shrinker_scan(struct shrinker *shrinker,
|
|
struct shrink_control *sc)
|
|
{
|
|
unsigned long pages_freed;
|
|
struct zs_pool *pool = container_of(shrinker, struct zs_pool,
|
|
shrinker);
|
|
|
|
pages_freed = pool->stats.pages_compacted;
|
|
/*
|
|
* Compact classes and calculate compaction delta.
|
|
* Can run concurrently with a manually triggered
|
|
* (by user) compaction.
|
|
*/
|
|
pages_freed = zs_compact(pool) - pages_freed;
|
|
|
|
return pages_freed ? pages_freed : SHRINK_STOP;
|
|
}
|
|
|
|
static unsigned long zs_shrinker_count(struct shrinker *shrinker,
|
|
struct shrink_control *sc)
|
|
{
|
|
int i;
|
|
struct size_class *class;
|
|
unsigned long pages_to_free = 0;
|
|
struct zs_pool *pool = container_of(shrinker, struct zs_pool,
|
|
shrinker);
|
|
|
|
for (i = zs_size_classes - 1; i >= 0; i--) {
|
|
class = pool->size_class[i];
|
|
if (!class)
|
|
continue;
|
|
if (class->index != i)
|
|
continue;
|
|
|
|
pages_to_free += zs_can_compact(class);
|
|
}
|
|
|
|
return pages_to_free;
|
|
}
|
|
|
|
static void zs_unregister_shrinker(struct zs_pool *pool)
|
|
{
|
|
if (pool->shrinker_enabled) {
|
|
unregister_shrinker(&pool->shrinker);
|
|
pool->shrinker_enabled = false;
|
|
}
|
|
}
|
|
|
|
static int zs_register_shrinker(struct zs_pool *pool)
|
|
{
|
|
pool->shrinker.scan_objects = zs_shrinker_scan;
|
|
pool->shrinker.count_objects = zs_shrinker_count;
|
|
pool->shrinker.batch = 0;
|
|
pool->shrinker.seeks = DEFAULT_SEEKS;
|
|
|
|
return register_shrinker(&pool->shrinker);
|
|
}
|
|
|
|
/**
|
|
* zs_create_pool - Creates an allocation pool to work from.
|
|
* @flags: allocation flags used to allocate pool metadata
|
|
*
|
|
* This function must be called before anything when using
|
|
* the zsmalloc allocator.
|
|
*
|
|
* On success, a pointer to the newly created pool is returned,
|
|
* otherwise NULL.
|
|
*/
|
|
struct zs_pool *zs_create_pool(const char *name, gfp_t flags)
|
|
{
|
|
int i;
|
|
struct zs_pool *pool;
|
|
struct size_class *prev_class = NULL;
|
|
|
|
pool = kzalloc(sizeof(*pool), GFP_KERNEL);
|
|
if (!pool)
|
|
return NULL;
|
|
|
|
pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *),
|
|
GFP_KERNEL);
|
|
if (!pool->size_class) {
|
|
kfree(pool);
|
|
return NULL;
|
|
}
|
|
|
|
pool->name = kstrdup(name, GFP_KERNEL);
|
|
if (!pool->name)
|
|
goto err;
|
|
|
|
if (create_handle_cache(pool))
|
|
goto err;
|
|
|
|
/*
|
|
* Iterate reversly, because, size of size_class that we want to use
|
|
* for merging should be larger or equal to current size.
|
|
*/
|
|
for (i = zs_size_classes - 1; i >= 0; i--) {
|
|
int size;
|
|
int pages_per_zspage;
|
|
struct size_class *class;
|
|
|
|
size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
|
|
if (size > ZS_MAX_ALLOC_SIZE)
|
|
size = ZS_MAX_ALLOC_SIZE;
|
|
pages_per_zspage = get_pages_per_zspage(size);
|
|
|
|
/*
|
|
* size_class is used for normal zsmalloc operation such
|
|
* as alloc/free for that size. Although it is natural that we
|
|
* have one size_class for each size, there is a chance that we
|
|
* can get more memory utilization if we use one size_class for
|
|
* many different sizes whose size_class have same
|
|
* characteristics. So, we makes size_class point to
|
|
* previous size_class if possible.
|
|
*/
|
|
if (prev_class) {
|
|
if (can_merge(prev_class, size, pages_per_zspage)) {
|
|
pool->size_class[i] = prev_class;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
class = kzalloc(sizeof(struct size_class), GFP_KERNEL);
|
|
if (!class)
|
|
goto err;
|
|
|
|
class->size = size;
|
|
class->index = i;
|
|
class->pages_per_zspage = pages_per_zspage;
|
|
if (pages_per_zspage == 1 &&
|
|
get_maxobj_per_zspage(size, pages_per_zspage) == 1)
|
|
class->huge = true;
|
|
spin_lock_init(&class->lock);
|
|
pool->size_class[i] = class;
|
|
|
|
prev_class = class;
|
|
}
|
|
|
|
pool->flags = flags;
|
|
|
|
if (zs_pool_stat_create(name, pool))
|
|
goto err;
|
|
|
|
/*
|
|
* Not critical, we still can use the pool
|
|
* and user can trigger compaction manually.
|
|
*/
|
|
if (zs_register_shrinker(pool) == 0)
|
|
pool->shrinker_enabled = true;
|
|
return pool;
|
|
|
|
err:
|
|
zs_destroy_pool(pool);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(zs_create_pool);
|
|
|
|
void zs_destroy_pool(struct zs_pool *pool)
|
|
{
|
|
int i;
|
|
|
|
zs_unregister_shrinker(pool);
|
|
zs_pool_stat_destroy(pool);
|
|
|
|
for (i = 0; i < zs_size_classes; i++) {
|
|
int fg;
|
|
struct size_class *class = pool->size_class[i];
|
|
|
|
if (!class)
|
|
continue;
|
|
|
|
if (class->index != i)
|
|
continue;
|
|
|
|
for (fg = 0; fg < _ZS_NR_FULLNESS_GROUPS; fg++) {
|
|
if (class->fullness_list[fg]) {
|
|
pr_info("Freeing non-empty class with size %db, fullness group %d\n",
|
|
class->size, fg);
|
|
}
|
|
}
|
|
kfree(class);
|
|
}
|
|
|
|
destroy_handle_cache(pool);
|
|
kfree(pool->size_class);
|
|
kfree(pool->name);
|
|
kfree(pool);
|
|
}
|
|
EXPORT_SYMBOL_GPL(zs_destroy_pool);
|
|
|
|
static int __init zs_init(void)
|
|
{
|
|
int ret = zs_register_cpu_notifier();
|
|
|
|
if (ret)
|
|
goto notifier_fail;
|
|
|
|
init_zs_size_classes();
|
|
|
|
#ifdef CONFIG_ZPOOL
|
|
zpool_register_driver(&zs_zpool_driver);
|
|
#endif
|
|
|
|
ret = zs_stat_init();
|
|
if (ret) {
|
|
pr_err("zs stat initialization failed\n");
|
|
goto stat_fail;
|
|
}
|
|
return 0;
|
|
|
|
stat_fail:
|
|
#ifdef CONFIG_ZPOOL
|
|
zpool_unregister_driver(&zs_zpool_driver);
|
|
#endif
|
|
notifier_fail:
|
|
zs_unregister_cpu_notifier();
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void __exit zs_exit(void)
|
|
{
|
|
#ifdef CONFIG_ZPOOL
|
|
zpool_unregister_driver(&zs_zpool_driver);
|
|
#endif
|
|
zs_unregister_cpu_notifier();
|
|
|
|
zs_stat_exit();
|
|
}
|
|
|
|
module_init(zs_init);
|
|
module_exit(zs_exit);
|
|
|
|
MODULE_LICENSE("Dual BSD/GPL");
|
|
MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
|