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![Domenico Cerasuolo](/assets/img/avatar_default.png)
Since zswap now writes back pages from memcg-specific LRUs, we now need a new stat to show writebacks count for each memcg. [nphamcs@gmail.com: rename ZSWP_WB to ZSWPWB] Link: https://lkml.kernel.org/r/20231205193307.2432803-1-nphamcs@gmail.com Link: https://lkml.kernel.org/r/20231130194023.4102148-5-nphamcs@gmail.com Suggested-by: Nhat Pham <nphamcs@gmail.com> Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com> Signed-off-by: Nhat Pham <nphamcs@gmail.com> Tested-by: Bagas Sanjaya <bagasdotme@gmail.com> Reviewed-by: Yosry Ahmed <yosryahmed@google.com> Cc: Chris Li <chrisl@kernel.org> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Seth Jennings <sjenning@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vitaly Wool <vitaly.wool@konsulko.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1824 lines
48 KiB
C
1824 lines
48 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* zswap.c - zswap driver file
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*
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* zswap is a cache that takes pages that are in the process
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* of being swapped out and attempts to compress and store them in a
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* RAM-based memory pool. This can result in a significant I/O reduction on
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* the swap device and, in the case where decompressing from RAM is faster
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* than reading from the swap device, can also improve workload performance.
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*
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* Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/cpu.h>
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#include <linux/highmem.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/types.h>
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#include <linux/atomic.h>
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#include <linux/rbtree.h>
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#include <linux/swap.h>
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#include <linux/crypto.h>
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#include <linux/scatterlist.h>
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#include <linux/mempolicy.h>
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#include <linux/mempool.h>
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#include <linux/zpool.h>
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#include <crypto/acompress.h>
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#include <linux/zswap.h>
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#include <linux/mm_types.h>
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#include <linux/page-flags.h>
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#include <linux/swapops.h>
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#include <linux/writeback.h>
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#include <linux/pagemap.h>
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#include <linux/workqueue.h>
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#include <linux/list_lru.h>
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#include "swap.h"
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#include "internal.h"
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/*********************************
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* statistics
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**********************************/
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/* Total bytes used by the compressed storage */
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u64 zswap_pool_total_size;
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/* The number of compressed pages currently stored in zswap */
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atomic_t zswap_stored_pages = ATOMIC_INIT(0);
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/* The number of same-value filled pages currently stored in zswap */
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static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0);
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/*
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* The statistics below are not protected from concurrent access for
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* performance reasons so they may not be a 100% accurate. However,
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* they do provide useful information on roughly how many times a
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* certain event is occurring.
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*/
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/* Pool limit was hit (see zswap_max_pool_percent) */
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static u64 zswap_pool_limit_hit;
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/* Pages written back when pool limit was reached */
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static u64 zswap_written_back_pages;
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/* Store failed due to a reclaim failure after pool limit was reached */
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static u64 zswap_reject_reclaim_fail;
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/* Store failed due to compression algorithm failure */
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static u64 zswap_reject_compress_fail;
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/* Compressed page was too big for the allocator to (optimally) store */
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static u64 zswap_reject_compress_poor;
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/* Store failed because underlying allocator could not get memory */
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static u64 zswap_reject_alloc_fail;
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/* Store failed because the entry metadata could not be allocated (rare) */
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static u64 zswap_reject_kmemcache_fail;
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/* Duplicate store was encountered (rare) */
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static u64 zswap_duplicate_entry;
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/* Shrinker work queue */
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static struct workqueue_struct *shrink_wq;
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/* Pool limit was hit, we need to calm down */
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static bool zswap_pool_reached_full;
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/*********************************
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* tunables
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**********************************/
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#define ZSWAP_PARAM_UNSET ""
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static int zswap_setup(void);
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/* Enable/disable zswap */
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static bool zswap_enabled = IS_ENABLED(CONFIG_ZSWAP_DEFAULT_ON);
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static int zswap_enabled_param_set(const char *,
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const struct kernel_param *);
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static const struct kernel_param_ops zswap_enabled_param_ops = {
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.set = zswap_enabled_param_set,
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.get = param_get_bool,
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};
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module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644);
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/* Crypto compressor to use */
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static char *zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
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static int zswap_compressor_param_set(const char *,
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const struct kernel_param *);
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static const struct kernel_param_ops zswap_compressor_param_ops = {
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.set = zswap_compressor_param_set,
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.get = param_get_charp,
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.free = param_free_charp,
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};
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module_param_cb(compressor, &zswap_compressor_param_ops,
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&zswap_compressor, 0644);
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/* Compressed storage zpool to use */
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static char *zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
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static int zswap_zpool_param_set(const char *, const struct kernel_param *);
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static const struct kernel_param_ops zswap_zpool_param_ops = {
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.set = zswap_zpool_param_set,
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.get = param_get_charp,
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.free = param_free_charp,
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};
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module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644);
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/* The maximum percentage of memory that the compressed pool can occupy */
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static unsigned int zswap_max_pool_percent = 20;
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module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644);
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/* The threshold for accepting new pages after the max_pool_percent was hit */
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static unsigned int zswap_accept_thr_percent = 90; /* of max pool size */
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module_param_named(accept_threshold_percent, zswap_accept_thr_percent,
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uint, 0644);
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/*
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* Enable/disable handling same-value filled pages (enabled by default).
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* If disabled every page is considered non-same-value filled.
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*/
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static bool zswap_same_filled_pages_enabled = true;
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module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
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bool, 0644);
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/* Enable/disable handling non-same-value filled pages (enabled by default) */
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static bool zswap_non_same_filled_pages_enabled = true;
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module_param_named(non_same_filled_pages_enabled, zswap_non_same_filled_pages_enabled,
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bool, 0644);
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static bool zswap_exclusive_loads_enabled = IS_ENABLED(
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CONFIG_ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON);
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module_param_named(exclusive_loads, zswap_exclusive_loads_enabled, bool, 0644);
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/* Number of zpools in zswap_pool (empirically determined for scalability) */
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#define ZSWAP_NR_ZPOOLS 32
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/*********************************
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* data structures
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**********************************/
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struct crypto_acomp_ctx {
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struct crypto_acomp *acomp;
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struct acomp_req *req;
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struct crypto_wait wait;
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u8 *dstmem;
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struct mutex *mutex;
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};
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/*
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* The lock ordering is zswap_tree.lock -> zswap_pool.lru_lock.
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* The only case where lru_lock is not acquired while holding tree.lock is
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* when a zswap_entry is taken off the lru for writeback, in that case it
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* needs to be verified that it's still valid in the tree.
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*/
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struct zswap_pool {
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struct zpool *zpools[ZSWAP_NR_ZPOOLS];
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struct crypto_acomp_ctx __percpu *acomp_ctx;
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struct kref kref;
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struct list_head list;
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struct work_struct release_work;
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struct work_struct shrink_work;
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struct hlist_node node;
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char tfm_name[CRYPTO_MAX_ALG_NAME];
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struct list_lru list_lru;
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struct mem_cgroup *next_shrink;
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};
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/*
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* struct zswap_entry
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*
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* This structure contains the metadata for tracking a single compressed
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* page within zswap.
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*
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* rbnode - links the entry into red-black tree for the appropriate swap type
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* swpentry - associated swap entry, the offset indexes into the red-black tree
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* refcount - the number of outstanding reference to the entry. This is needed
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* to protect against premature freeing of the entry by code
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* concurrent calls to load, invalidate, and writeback. The lock
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* for the zswap_tree structure that contains the entry must
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* be held while changing the refcount. Since the lock must
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* be held, there is no reason to also make refcount atomic.
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* length - the length in bytes of the compressed page data. Needed during
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* decompression. For a same value filled page length is 0, and both
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* pool and lru are invalid and must be ignored.
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* pool - the zswap_pool the entry's data is in
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* handle - zpool allocation handle that stores the compressed page data
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* value - value of the same-value filled pages which have same content
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* objcg - the obj_cgroup that the compressed memory is charged to
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* lru - handle to the pool's lru used to evict pages.
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*/
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struct zswap_entry {
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struct rb_node rbnode;
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swp_entry_t swpentry;
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int refcount;
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unsigned int length;
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struct zswap_pool *pool;
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union {
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unsigned long handle;
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unsigned long value;
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};
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struct obj_cgroup *objcg;
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struct list_head lru;
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};
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/*
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* The tree lock in the zswap_tree struct protects a few things:
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* - the rbtree
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* - the refcount field of each entry in the tree
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*/
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struct zswap_tree {
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struct rb_root rbroot;
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spinlock_t lock;
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};
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static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
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/* RCU-protected iteration */
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static LIST_HEAD(zswap_pools);
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/* protects zswap_pools list modification */
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static DEFINE_SPINLOCK(zswap_pools_lock);
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/* pool counter to provide unique names to zpool */
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static atomic_t zswap_pools_count = ATOMIC_INIT(0);
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enum zswap_init_type {
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ZSWAP_UNINIT,
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ZSWAP_INIT_SUCCEED,
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ZSWAP_INIT_FAILED
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};
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static enum zswap_init_type zswap_init_state;
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/* used to ensure the integrity of initialization */
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static DEFINE_MUTEX(zswap_init_lock);
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/* init completed, but couldn't create the initial pool */
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static bool zswap_has_pool;
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/*********************************
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* helpers and fwd declarations
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**********************************/
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#define zswap_pool_debug(msg, p) \
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pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name, \
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zpool_get_type((p)->zpools[0]))
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static int zswap_writeback_entry(struct zswap_entry *entry,
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struct zswap_tree *tree);
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static int zswap_pool_get(struct zswap_pool *pool);
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static void zswap_pool_put(struct zswap_pool *pool);
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static bool zswap_is_full(void)
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{
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return totalram_pages() * zswap_max_pool_percent / 100 <
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DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
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}
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static bool zswap_can_accept(void)
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{
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return totalram_pages() * zswap_accept_thr_percent / 100 *
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zswap_max_pool_percent / 100 >
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DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
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}
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static void zswap_update_total_size(void)
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{
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struct zswap_pool *pool;
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u64 total = 0;
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int i;
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rcu_read_lock();
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list_for_each_entry_rcu(pool, &zswap_pools, list)
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for (i = 0; i < ZSWAP_NR_ZPOOLS; i++)
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total += zpool_get_total_size(pool->zpools[i]);
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rcu_read_unlock();
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zswap_pool_total_size = total;
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}
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/* should be called under RCU */
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#ifdef CONFIG_MEMCG
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static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entry *entry)
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{
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return entry->objcg ? obj_cgroup_memcg(entry->objcg) : NULL;
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}
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#else
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static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entry *entry)
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{
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return NULL;
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}
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#endif
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static inline int entry_to_nid(struct zswap_entry *entry)
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{
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return page_to_nid(virt_to_page(entry));
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}
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void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg)
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{
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struct zswap_pool *pool;
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/* lock out zswap pools list modification */
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spin_lock(&zswap_pools_lock);
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list_for_each_entry(pool, &zswap_pools, list) {
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if (pool->next_shrink == memcg)
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pool->next_shrink = mem_cgroup_iter(NULL, pool->next_shrink, NULL);
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}
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spin_unlock(&zswap_pools_lock);
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}
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/*********************************
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* zswap entry functions
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**********************************/
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static struct kmem_cache *zswap_entry_cache;
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static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp, int nid)
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{
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struct zswap_entry *entry;
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entry = kmem_cache_alloc_node(zswap_entry_cache, gfp, nid);
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if (!entry)
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return NULL;
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entry->refcount = 1;
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RB_CLEAR_NODE(&entry->rbnode);
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return entry;
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}
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static void zswap_entry_cache_free(struct zswap_entry *entry)
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{
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kmem_cache_free(zswap_entry_cache, entry);
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}
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/*********************************
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* lru functions
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**********************************/
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static void zswap_lru_add(struct list_lru *list_lru, struct zswap_entry *entry)
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{
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int nid = entry_to_nid(entry);
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struct mem_cgroup *memcg;
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/*
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* Note that it is safe to use rcu_read_lock() here, even in the face of
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* concurrent memcg offlining. Thanks to the memcg->kmemcg_id indirection
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* used in list_lru lookup, only two scenarios are possible:
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*
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* 1. list_lru_add() is called before memcg->kmemcg_id is updated. The
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* new entry will be reparented to memcg's parent's list_lru.
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* 2. list_lru_add() is called after memcg->kmemcg_id is updated. The
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* new entry will be added directly to memcg's parent's list_lru.
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*
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* Similar reasoning holds for list_lru_del() and list_lru_putback().
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*/
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rcu_read_lock();
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memcg = mem_cgroup_from_entry(entry);
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/* will always succeed */
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list_lru_add(list_lru, &entry->lru, nid, memcg);
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rcu_read_unlock();
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}
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static void zswap_lru_del(struct list_lru *list_lru, struct zswap_entry *entry)
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{
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int nid = entry_to_nid(entry);
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struct mem_cgroup *memcg;
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rcu_read_lock();
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memcg = mem_cgroup_from_entry(entry);
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/* will always succeed */
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list_lru_del(list_lru, &entry->lru, nid, memcg);
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rcu_read_unlock();
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}
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static void zswap_lru_putback(struct list_lru *list_lru,
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struct zswap_entry *entry)
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{
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int nid = entry_to_nid(entry);
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spinlock_t *lock = &list_lru->node[nid].lock;
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struct mem_cgroup *memcg;
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rcu_read_lock();
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memcg = mem_cgroup_from_entry(entry);
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spin_lock(lock);
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/* we cannot use list_lru_add here, because it increments node's lru count */
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list_lru_putback(list_lru, &entry->lru, nid, memcg);
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spin_unlock(lock);
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rcu_read_unlock();
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}
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/*********************************
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* rbtree functions
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**********************************/
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static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
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{
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struct rb_node *node = root->rb_node;
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struct zswap_entry *entry;
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pgoff_t entry_offset;
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while (node) {
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entry = rb_entry(node, struct zswap_entry, rbnode);
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entry_offset = swp_offset(entry->swpentry);
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if (entry_offset > offset)
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node = node->rb_left;
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else if (entry_offset < offset)
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node = node->rb_right;
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else
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return entry;
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}
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return NULL;
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}
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/*
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* In the case that a entry with the same offset is found, a pointer to
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* the existing entry is stored in dupentry and the function returns -EEXIST
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*/
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static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
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struct zswap_entry **dupentry)
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{
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struct rb_node **link = &root->rb_node, *parent = NULL;
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struct zswap_entry *myentry;
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pgoff_t myentry_offset, entry_offset = swp_offset(entry->swpentry);
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while (*link) {
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parent = *link;
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myentry = rb_entry(parent, struct zswap_entry, rbnode);
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myentry_offset = swp_offset(myentry->swpentry);
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if (myentry_offset > entry_offset)
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link = &(*link)->rb_left;
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else if (myentry_offset < entry_offset)
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link = &(*link)->rb_right;
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else {
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*dupentry = myentry;
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return -EEXIST;
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}
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}
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rb_link_node(&entry->rbnode, parent, link);
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rb_insert_color(&entry->rbnode, root);
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return 0;
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}
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static bool zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
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{
|
|
if (!RB_EMPTY_NODE(&entry->rbnode)) {
|
|
rb_erase(&entry->rbnode, root);
|
|
RB_CLEAR_NODE(&entry->rbnode);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static struct zpool *zswap_find_zpool(struct zswap_entry *entry)
|
|
{
|
|
int i = 0;
|
|
|
|
if (ZSWAP_NR_ZPOOLS > 1)
|
|
i = hash_ptr(entry, ilog2(ZSWAP_NR_ZPOOLS));
|
|
|
|
return entry->pool->zpools[i];
|
|
}
|
|
|
|
/*
|
|
* Carries out the common pattern of freeing and entry's zpool allocation,
|
|
* freeing the entry itself, and decrementing the number of stored pages.
|
|
*/
|
|
static void zswap_free_entry(struct zswap_entry *entry)
|
|
{
|
|
if (entry->objcg) {
|
|
obj_cgroup_uncharge_zswap(entry->objcg, entry->length);
|
|
obj_cgroup_put(entry->objcg);
|
|
}
|
|
if (!entry->length)
|
|
atomic_dec(&zswap_same_filled_pages);
|
|
else {
|
|
zswap_lru_del(&entry->pool->list_lru, entry);
|
|
zpool_free(zswap_find_zpool(entry), entry->handle);
|
|
zswap_pool_put(entry->pool);
|
|
}
|
|
zswap_entry_cache_free(entry);
|
|
atomic_dec(&zswap_stored_pages);
|
|
zswap_update_total_size();
|
|
}
|
|
|
|
/* caller must hold the tree lock */
|
|
static void zswap_entry_get(struct zswap_entry *entry)
|
|
{
|
|
entry->refcount++;
|
|
}
|
|
|
|
/* caller must hold the tree lock
|
|
* remove from the tree and free it, if nobody reference the entry
|
|
*/
|
|
static void zswap_entry_put(struct zswap_tree *tree,
|
|
struct zswap_entry *entry)
|
|
{
|
|
int refcount = --entry->refcount;
|
|
|
|
WARN_ON_ONCE(refcount < 0);
|
|
if (refcount == 0) {
|
|
WARN_ON_ONCE(!RB_EMPTY_NODE(&entry->rbnode));
|
|
zswap_free_entry(entry);
|
|
}
|
|
}
|
|
|
|
/* caller must hold the tree lock */
|
|
static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
|
|
pgoff_t offset)
|
|
{
|
|
struct zswap_entry *entry;
|
|
|
|
entry = zswap_rb_search(root, offset);
|
|
if (entry)
|
|
zswap_entry_get(entry);
|
|
|
|
return entry;
|
|
}
|
|
|
|
/*********************************
|
|
* per-cpu code
|
|
**********************************/
|
|
static DEFINE_PER_CPU(u8 *, zswap_dstmem);
|
|
/*
|
|
* If users dynamically change the zpool type and compressor at runtime, i.e.
|
|
* zswap is running, zswap can have more than one zpool on one cpu, but they
|
|
* are sharing dtsmem. So we need this mutex to be per-cpu.
|
|
*/
|
|
static DEFINE_PER_CPU(struct mutex *, zswap_mutex);
|
|
|
|
static int zswap_dstmem_prepare(unsigned int cpu)
|
|
{
|
|
struct mutex *mutex;
|
|
u8 *dst;
|
|
|
|
dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
|
|
if (!dst)
|
|
return -ENOMEM;
|
|
|
|
mutex = kmalloc_node(sizeof(*mutex), GFP_KERNEL, cpu_to_node(cpu));
|
|
if (!mutex) {
|
|
kfree(dst);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
mutex_init(mutex);
|
|
per_cpu(zswap_dstmem, cpu) = dst;
|
|
per_cpu(zswap_mutex, cpu) = mutex;
|
|
return 0;
|
|
}
|
|
|
|
static int zswap_dstmem_dead(unsigned int cpu)
|
|
{
|
|
struct mutex *mutex;
|
|
u8 *dst;
|
|
|
|
mutex = per_cpu(zswap_mutex, cpu);
|
|
kfree(mutex);
|
|
per_cpu(zswap_mutex, cpu) = NULL;
|
|
|
|
dst = per_cpu(zswap_dstmem, cpu);
|
|
kfree(dst);
|
|
per_cpu(zswap_dstmem, cpu) = NULL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
|
|
{
|
|
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
|
|
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
|
|
struct crypto_acomp *acomp;
|
|
struct acomp_req *req;
|
|
|
|
acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
|
|
if (IS_ERR(acomp)) {
|
|
pr_err("could not alloc crypto acomp %s : %ld\n",
|
|
pool->tfm_name, PTR_ERR(acomp));
|
|
return PTR_ERR(acomp);
|
|
}
|
|
acomp_ctx->acomp = acomp;
|
|
|
|
req = acomp_request_alloc(acomp_ctx->acomp);
|
|
if (!req) {
|
|
pr_err("could not alloc crypto acomp_request %s\n",
|
|
pool->tfm_name);
|
|
crypto_free_acomp(acomp_ctx->acomp);
|
|
return -ENOMEM;
|
|
}
|
|
acomp_ctx->req = req;
|
|
|
|
crypto_init_wait(&acomp_ctx->wait);
|
|
/*
|
|
* if the backend of acomp is async zip, crypto_req_done() will wakeup
|
|
* crypto_wait_req(); if the backend of acomp is scomp, the callback
|
|
* won't be called, crypto_wait_req() will return without blocking.
|
|
*/
|
|
acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
|
|
crypto_req_done, &acomp_ctx->wait);
|
|
|
|
acomp_ctx->mutex = per_cpu(zswap_mutex, cpu);
|
|
acomp_ctx->dstmem = per_cpu(zswap_dstmem, cpu);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
|
|
{
|
|
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
|
|
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
|
|
|
|
if (!IS_ERR_OR_NULL(acomp_ctx)) {
|
|
if (!IS_ERR_OR_NULL(acomp_ctx->req))
|
|
acomp_request_free(acomp_ctx->req);
|
|
if (!IS_ERR_OR_NULL(acomp_ctx->acomp))
|
|
crypto_free_acomp(acomp_ctx->acomp);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*********************************
|
|
* pool functions
|
|
**********************************/
|
|
|
|
static struct zswap_pool *__zswap_pool_current(void)
|
|
{
|
|
struct zswap_pool *pool;
|
|
|
|
pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
|
|
WARN_ONCE(!pool && zswap_has_pool,
|
|
"%s: no page storage pool!\n", __func__);
|
|
|
|
return pool;
|
|
}
|
|
|
|
static struct zswap_pool *zswap_pool_current(void)
|
|
{
|
|
assert_spin_locked(&zswap_pools_lock);
|
|
|
|
return __zswap_pool_current();
|
|
}
|
|
|
|
static struct zswap_pool *zswap_pool_current_get(void)
|
|
{
|
|
struct zswap_pool *pool;
|
|
|
|
rcu_read_lock();
|
|
|
|
pool = __zswap_pool_current();
|
|
if (!zswap_pool_get(pool))
|
|
pool = NULL;
|
|
|
|
rcu_read_unlock();
|
|
|
|
return pool;
|
|
}
|
|
|
|
static struct zswap_pool *zswap_pool_last_get(void)
|
|
{
|
|
struct zswap_pool *pool, *last = NULL;
|
|
|
|
rcu_read_lock();
|
|
|
|
list_for_each_entry_rcu(pool, &zswap_pools, list)
|
|
last = pool;
|
|
WARN_ONCE(!last && zswap_has_pool,
|
|
"%s: no page storage pool!\n", __func__);
|
|
if (!zswap_pool_get(last))
|
|
last = NULL;
|
|
|
|
rcu_read_unlock();
|
|
|
|
return last;
|
|
}
|
|
|
|
/* type and compressor must be null-terminated */
|
|
static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor)
|
|
{
|
|
struct zswap_pool *pool;
|
|
|
|
assert_spin_locked(&zswap_pools_lock);
|
|
|
|
list_for_each_entry_rcu(pool, &zswap_pools, list) {
|
|
if (strcmp(pool->tfm_name, compressor))
|
|
continue;
|
|
/* all zpools share the same type */
|
|
if (strcmp(zpool_get_type(pool->zpools[0]), type))
|
|
continue;
|
|
/* if we can't get it, it's about to be destroyed */
|
|
if (!zswap_pool_get(pool))
|
|
continue;
|
|
return pool;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* If the entry is still valid in the tree, drop the initial ref and remove it
|
|
* from the tree. This function must be called with an additional ref held,
|
|
* otherwise it may race with another invalidation freeing the entry.
|
|
*/
|
|
static void zswap_invalidate_entry(struct zswap_tree *tree,
|
|
struct zswap_entry *entry)
|
|
{
|
|
if (zswap_rb_erase(&tree->rbroot, entry))
|
|
zswap_entry_put(tree, entry);
|
|
}
|
|
|
|
static enum lru_status shrink_memcg_cb(struct list_head *item, struct list_lru_one *l,
|
|
spinlock_t *lock, void *arg)
|
|
{
|
|
struct zswap_entry *entry = container_of(item, struct zswap_entry, lru);
|
|
struct zswap_tree *tree;
|
|
pgoff_t swpoffset;
|
|
enum lru_status ret = LRU_REMOVED_RETRY;
|
|
int writeback_result;
|
|
|
|
/*
|
|
* Once the lru lock is dropped, the entry might get freed. The
|
|
* swpoffset is copied to the stack, and entry isn't deref'd again
|
|
* until the entry is verified to still be alive in the tree.
|
|
*/
|
|
swpoffset = swp_offset(entry->swpentry);
|
|
tree = zswap_trees[swp_type(entry->swpentry)];
|
|
list_lru_isolate(l, item);
|
|
/*
|
|
* It's safe to drop the lock here because we return either
|
|
* LRU_REMOVED_RETRY or LRU_RETRY.
|
|
*/
|
|
spin_unlock(lock);
|
|
|
|
/* Check for invalidate() race */
|
|
spin_lock(&tree->lock);
|
|
if (entry != zswap_rb_search(&tree->rbroot, swpoffset))
|
|
goto unlock;
|
|
|
|
/* Hold a reference to prevent a free during writeback */
|
|
zswap_entry_get(entry);
|
|
spin_unlock(&tree->lock);
|
|
|
|
writeback_result = zswap_writeback_entry(entry, tree);
|
|
|
|
spin_lock(&tree->lock);
|
|
if (writeback_result) {
|
|
zswap_reject_reclaim_fail++;
|
|
zswap_lru_putback(&entry->pool->list_lru, entry);
|
|
ret = LRU_RETRY;
|
|
goto put_unlock;
|
|
}
|
|
zswap_written_back_pages++;
|
|
|
|
if (entry->objcg)
|
|
count_objcg_event(entry->objcg, ZSWPWB);
|
|
|
|
count_vm_event(ZSWPWB);
|
|
/*
|
|
* Writeback started successfully, the page now belongs to the
|
|
* swapcache. Drop the entry from zswap - unless invalidate already
|
|
* took it out while we had the tree->lock released for IO.
|
|
*/
|
|
zswap_invalidate_entry(tree, entry);
|
|
|
|
put_unlock:
|
|
/* Drop local reference */
|
|
zswap_entry_put(tree, entry);
|
|
unlock:
|
|
spin_unlock(&tree->lock);
|
|
spin_lock(lock);
|
|
return ret;
|
|
}
|
|
|
|
static int shrink_memcg(struct mem_cgroup *memcg)
|
|
{
|
|
struct zswap_pool *pool;
|
|
int nid, shrunk = 0;
|
|
|
|
/*
|
|
* Skip zombies because their LRUs are reparented and we would be
|
|
* reclaiming from the parent instead of the dead memcg.
|
|
*/
|
|
if (memcg && !mem_cgroup_online(memcg))
|
|
return -ENOENT;
|
|
|
|
pool = zswap_pool_current_get();
|
|
if (!pool)
|
|
return -EINVAL;
|
|
|
|
for_each_node_state(nid, N_NORMAL_MEMORY) {
|
|
unsigned long nr_to_walk = 1;
|
|
|
|
shrunk += list_lru_walk_one(&pool->list_lru, nid, memcg,
|
|
&shrink_memcg_cb, NULL, &nr_to_walk);
|
|
}
|
|
zswap_pool_put(pool);
|
|
return shrunk ? 0 : -EAGAIN;
|
|
}
|
|
|
|
static void shrink_worker(struct work_struct *w)
|
|
{
|
|
struct zswap_pool *pool = container_of(w, typeof(*pool),
|
|
shrink_work);
|
|
struct mem_cgroup *memcg;
|
|
int ret, failures = 0;
|
|
|
|
/* global reclaim will select cgroup in a round-robin fashion. */
|
|
do {
|
|
spin_lock(&zswap_pools_lock);
|
|
pool->next_shrink = mem_cgroup_iter(NULL, pool->next_shrink, NULL);
|
|
memcg = pool->next_shrink;
|
|
|
|
/*
|
|
* We need to retry if we have gone through a full round trip, or if we
|
|
* got an offline memcg (or else we risk undoing the effect of the
|
|
* zswap memcg offlining cleanup callback). This is not catastrophic
|
|
* per se, but it will keep the now offlined memcg hostage for a while.
|
|
*
|
|
* Note that if we got an online memcg, we will keep the extra
|
|
* reference in case the original reference obtained by mem_cgroup_iter
|
|
* is dropped by the zswap memcg offlining callback, ensuring that the
|
|
* memcg is not killed when we are reclaiming.
|
|
*/
|
|
if (!memcg) {
|
|
spin_unlock(&zswap_pools_lock);
|
|
if (++failures == MAX_RECLAIM_RETRIES)
|
|
break;
|
|
|
|
goto resched;
|
|
}
|
|
|
|
if (!mem_cgroup_tryget_online(memcg)) {
|
|
/* drop the reference from mem_cgroup_iter() */
|
|
mem_cgroup_iter_break(NULL, memcg);
|
|
pool->next_shrink = NULL;
|
|
spin_unlock(&zswap_pools_lock);
|
|
|
|
if (++failures == MAX_RECLAIM_RETRIES)
|
|
break;
|
|
|
|
goto resched;
|
|
}
|
|
spin_unlock(&zswap_pools_lock);
|
|
|
|
ret = shrink_memcg(memcg);
|
|
/* drop the extra reference */
|
|
mem_cgroup_put(memcg);
|
|
|
|
if (ret == -EINVAL)
|
|
break;
|
|
if (ret && ++failures == MAX_RECLAIM_RETRIES)
|
|
break;
|
|
|
|
resched:
|
|
cond_resched();
|
|
} while (!zswap_can_accept());
|
|
zswap_pool_put(pool);
|
|
}
|
|
|
|
static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
|
|
{
|
|
int i;
|
|
struct zswap_pool *pool;
|
|
char name[38]; /* 'zswap' + 32 char (max) num + \0 */
|
|
gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
|
|
int ret;
|
|
|
|
if (!zswap_has_pool) {
|
|
/* if either are unset, pool initialization failed, and we
|
|
* need both params to be set correctly before trying to
|
|
* create a pool.
|
|
*/
|
|
if (!strcmp(type, ZSWAP_PARAM_UNSET))
|
|
return NULL;
|
|
if (!strcmp(compressor, ZSWAP_PARAM_UNSET))
|
|
return NULL;
|
|
}
|
|
|
|
pool = kzalloc(sizeof(*pool), GFP_KERNEL);
|
|
if (!pool)
|
|
return NULL;
|
|
|
|
for (i = 0; i < ZSWAP_NR_ZPOOLS; i++) {
|
|
/* unique name for each pool specifically required by zsmalloc */
|
|
snprintf(name, 38, "zswap%x",
|
|
atomic_inc_return(&zswap_pools_count));
|
|
|
|
pool->zpools[i] = zpool_create_pool(type, name, gfp);
|
|
if (!pool->zpools[i]) {
|
|
pr_err("%s zpool not available\n", type);
|
|
goto error;
|
|
}
|
|
}
|
|
pr_debug("using %s zpool\n", zpool_get_type(pool->zpools[0]));
|
|
|
|
strscpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
|
|
|
|
pool->acomp_ctx = alloc_percpu(*pool->acomp_ctx);
|
|
if (!pool->acomp_ctx) {
|
|
pr_err("percpu alloc failed\n");
|
|
goto error;
|
|
}
|
|
|
|
ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
|
|
&pool->node);
|
|
if (ret)
|
|
goto error;
|
|
pr_debug("using %s compressor\n", pool->tfm_name);
|
|
|
|
/* being the current pool takes 1 ref; this func expects the
|
|
* caller to always add the new pool as the current pool
|
|
*/
|
|
kref_init(&pool->kref);
|
|
INIT_LIST_HEAD(&pool->list);
|
|
list_lru_init_memcg(&pool->list_lru, NULL);
|
|
INIT_WORK(&pool->shrink_work, shrink_worker);
|
|
|
|
zswap_pool_debug("created", pool);
|
|
|
|
return pool;
|
|
|
|
error:
|
|
if (pool->acomp_ctx)
|
|
free_percpu(pool->acomp_ctx);
|
|
while (i--)
|
|
zpool_destroy_pool(pool->zpools[i]);
|
|
kfree(pool);
|
|
return NULL;
|
|
}
|
|
|
|
static struct zswap_pool *__zswap_pool_create_fallback(void)
|
|
{
|
|
bool has_comp, has_zpool;
|
|
|
|
has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
|
|
if (!has_comp && strcmp(zswap_compressor,
|
|
CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) {
|
|
pr_err("compressor %s not available, using default %s\n",
|
|
zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
|
|
param_free_charp(&zswap_compressor);
|
|
zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
|
|
has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
|
|
}
|
|
if (!has_comp) {
|
|
pr_err("default compressor %s not available\n",
|
|
zswap_compressor);
|
|
param_free_charp(&zswap_compressor);
|
|
zswap_compressor = ZSWAP_PARAM_UNSET;
|
|
}
|
|
|
|
has_zpool = zpool_has_pool(zswap_zpool_type);
|
|
if (!has_zpool && strcmp(zswap_zpool_type,
|
|
CONFIG_ZSWAP_ZPOOL_DEFAULT)) {
|
|
pr_err("zpool %s not available, using default %s\n",
|
|
zswap_zpool_type, CONFIG_ZSWAP_ZPOOL_DEFAULT);
|
|
param_free_charp(&zswap_zpool_type);
|
|
zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
|
|
has_zpool = zpool_has_pool(zswap_zpool_type);
|
|
}
|
|
if (!has_zpool) {
|
|
pr_err("default zpool %s not available\n",
|
|
zswap_zpool_type);
|
|
param_free_charp(&zswap_zpool_type);
|
|
zswap_zpool_type = ZSWAP_PARAM_UNSET;
|
|
}
|
|
|
|
if (!has_comp || !has_zpool)
|
|
return NULL;
|
|
|
|
return zswap_pool_create(zswap_zpool_type, zswap_compressor);
|
|
}
|
|
|
|
static void zswap_pool_destroy(struct zswap_pool *pool)
|
|
{
|
|
int i;
|
|
|
|
zswap_pool_debug("destroying", pool);
|
|
|
|
cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
|
|
free_percpu(pool->acomp_ctx);
|
|
list_lru_destroy(&pool->list_lru);
|
|
|
|
spin_lock(&zswap_pools_lock);
|
|
mem_cgroup_iter_break(NULL, pool->next_shrink);
|
|
pool->next_shrink = NULL;
|
|
spin_unlock(&zswap_pools_lock);
|
|
|
|
for (i = 0; i < ZSWAP_NR_ZPOOLS; i++)
|
|
zpool_destroy_pool(pool->zpools[i]);
|
|
kfree(pool);
|
|
}
|
|
|
|
static int __must_check zswap_pool_get(struct zswap_pool *pool)
|
|
{
|
|
if (!pool)
|
|
return 0;
|
|
|
|
return kref_get_unless_zero(&pool->kref);
|
|
}
|
|
|
|
static void __zswap_pool_release(struct work_struct *work)
|
|
{
|
|
struct zswap_pool *pool = container_of(work, typeof(*pool),
|
|
release_work);
|
|
|
|
synchronize_rcu();
|
|
|
|
/* nobody should have been able to get a kref... */
|
|
WARN_ON(kref_get_unless_zero(&pool->kref));
|
|
|
|
/* pool is now off zswap_pools list and has no references. */
|
|
zswap_pool_destroy(pool);
|
|
}
|
|
|
|
static void __zswap_pool_empty(struct kref *kref)
|
|
{
|
|
struct zswap_pool *pool;
|
|
|
|
pool = container_of(kref, typeof(*pool), kref);
|
|
|
|
spin_lock(&zswap_pools_lock);
|
|
|
|
WARN_ON(pool == zswap_pool_current());
|
|
|
|
list_del_rcu(&pool->list);
|
|
|
|
INIT_WORK(&pool->release_work, __zswap_pool_release);
|
|
schedule_work(&pool->release_work);
|
|
|
|
spin_unlock(&zswap_pools_lock);
|
|
}
|
|
|
|
static void zswap_pool_put(struct zswap_pool *pool)
|
|
{
|
|
kref_put(&pool->kref, __zswap_pool_empty);
|
|
}
|
|
|
|
/*********************************
|
|
* param callbacks
|
|
**********************************/
|
|
|
|
static bool zswap_pool_changed(const char *s, const struct kernel_param *kp)
|
|
{
|
|
/* no change required */
|
|
if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/* val must be a null-terminated string */
|
|
static int __zswap_param_set(const char *val, const struct kernel_param *kp,
|
|
char *type, char *compressor)
|
|
{
|
|
struct zswap_pool *pool, *put_pool = NULL;
|
|
char *s = strstrip((char *)val);
|
|
int ret = 0;
|
|
bool new_pool = false;
|
|
|
|
mutex_lock(&zswap_init_lock);
|
|
switch (zswap_init_state) {
|
|
case ZSWAP_UNINIT:
|
|
/* if this is load-time (pre-init) param setting,
|
|
* don't create a pool; that's done during init.
|
|
*/
|
|
ret = param_set_charp(s, kp);
|
|
break;
|
|
case ZSWAP_INIT_SUCCEED:
|
|
new_pool = zswap_pool_changed(s, kp);
|
|
break;
|
|
case ZSWAP_INIT_FAILED:
|
|
pr_err("can't set param, initialization failed\n");
|
|
ret = -ENODEV;
|
|
}
|
|
mutex_unlock(&zswap_init_lock);
|
|
|
|
/* no need to create a new pool, return directly */
|
|
if (!new_pool)
|
|
return ret;
|
|
|
|
if (!type) {
|
|
if (!zpool_has_pool(s)) {
|
|
pr_err("zpool %s not available\n", s);
|
|
return -ENOENT;
|
|
}
|
|
type = s;
|
|
} else if (!compressor) {
|
|
if (!crypto_has_acomp(s, 0, 0)) {
|
|
pr_err("compressor %s not available\n", s);
|
|
return -ENOENT;
|
|
}
|
|
compressor = s;
|
|
} else {
|
|
WARN_ON(1);
|
|
return -EINVAL;
|
|
}
|
|
|
|
spin_lock(&zswap_pools_lock);
|
|
|
|
pool = zswap_pool_find_get(type, compressor);
|
|
if (pool) {
|
|
zswap_pool_debug("using existing", pool);
|
|
WARN_ON(pool == zswap_pool_current());
|
|
list_del_rcu(&pool->list);
|
|
}
|
|
|
|
spin_unlock(&zswap_pools_lock);
|
|
|
|
if (!pool)
|
|
pool = zswap_pool_create(type, compressor);
|
|
|
|
if (pool)
|
|
ret = param_set_charp(s, kp);
|
|
else
|
|
ret = -EINVAL;
|
|
|
|
spin_lock(&zswap_pools_lock);
|
|
|
|
if (!ret) {
|
|
put_pool = zswap_pool_current();
|
|
list_add_rcu(&pool->list, &zswap_pools);
|
|
zswap_has_pool = true;
|
|
} else if (pool) {
|
|
/* add the possibly pre-existing pool to the end of the pools
|
|
* list; if it's new (and empty) then it'll be removed and
|
|
* destroyed by the put after we drop the lock
|
|
*/
|
|
list_add_tail_rcu(&pool->list, &zswap_pools);
|
|
put_pool = pool;
|
|
}
|
|
|
|
spin_unlock(&zswap_pools_lock);
|
|
|
|
if (!zswap_has_pool && !pool) {
|
|
/* if initial pool creation failed, and this pool creation also
|
|
* failed, maybe both compressor and zpool params were bad.
|
|
* Allow changing this param, so pool creation will succeed
|
|
* when the other param is changed. We already verified this
|
|
* param is ok in the zpool_has_pool() or crypto_has_acomp()
|
|
* checks above.
|
|
*/
|
|
ret = param_set_charp(s, kp);
|
|
}
|
|
|
|
/* drop the ref from either the old current pool,
|
|
* or the new pool we failed to add
|
|
*/
|
|
if (put_pool)
|
|
zswap_pool_put(put_pool);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int zswap_compressor_param_set(const char *val,
|
|
const struct kernel_param *kp)
|
|
{
|
|
return __zswap_param_set(val, kp, zswap_zpool_type, NULL);
|
|
}
|
|
|
|
static int zswap_zpool_param_set(const char *val,
|
|
const struct kernel_param *kp)
|
|
{
|
|
return __zswap_param_set(val, kp, NULL, zswap_compressor);
|
|
}
|
|
|
|
static int zswap_enabled_param_set(const char *val,
|
|
const struct kernel_param *kp)
|
|
{
|
|
int ret = -ENODEV;
|
|
|
|
/* if this is load-time (pre-init) param setting, only set param. */
|
|
if (system_state != SYSTEM_RUNNING)
|
|
return param_set_bool(val, kp);
|
|
|
|
mutex_lock(&zswap_init_lock);
|
|
switch (zswap_init_state) {
|
|
case ZSWAP_UNINIT:
|
|
if (zswap_setup())
|
|
break;
|
|
fallthrough;
|
|
case ZSWAP_INIT_SUCCEED:
|
|
if (!zswap_has_pool)
|
|
pr_err("can't enable, no pool configured\n");
|
|
else
|
|
ret = param_set_bool(val, kp);
|
|
break;
|
|
case ZSWAP_INIT_FAILED:
|
|
pr_err("can't enable, initialization failed\n");
|
|
}
|
|
mutex_unlock(&zswap_init_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*********************************
|
|
* writeback code
|
|
**********************************/
|
|
/*
|
|
* Attempts to free an entry by adding a page to the swap cache,
|
|
* decompressing the entry data into the page, and issuing a
|
|
* bio write to write the page back to the swap device.
|
|
*
|
|
* This can be thought of as a "resumed writeback" of the page
|
|
* to the swap device. We are basically resuming the same swap
|
|
* writeback path that was intercepted with the zswap_store()
|
|
* in the first place. After the page has been decompressed into
|
|
* the swap cache, the compressed version stored by zswap can be
|
|
* freed.
|
|
*/
|
|
static int zswap_writeback_entry(struct zswap_entry *entry,
|
|
struct zswap_tree *tree)
|
|
{
|
|
swp_entry_t swpentry = entry->swpentry;
|
|
struct page *page;
|
|
struct mempolicy *mpol;
|
|
struct scatterlist input, output;
|
|
struct crypto_acomp_ctx *acomp_ctx;
|
|
struct zpool *pool = zswap_find_zpool(entry);
|
|
bool page_was_allocated;
|
|
u8 *src, *tmp = NULL;
|
|
unsigned int dlen;
|
|
int ret;
|
|
struct writeback_control wbc = {
|
|
.sync_mode = WB_SYNC_NONE,
|
|
};
|
|
|
|
if (!zpool_can_sleep_mapped(pool)) {
|
|
tmp = kmalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!tmp)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* try to allocate swap cache page */
|
|
mpol = get_task_policy(current);
|
|
page = __read_swap_cache_async(swpentry, GFP_KERNEL, mpol,
|
|
NO_INTERLEAVE_INDEX, &page_was_allocated, true);
|
|
if (!page) {
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
|
|
/* Found an existing page, we raced with load/swapin */
|
|
if (!page_was_allocated) {
|
|
put_page(page);
|
|
ret = -EEXIST;
|
|
goto fail;
|
|
}
|
|
|
|
/*
|
|
* Page is locked, and the swapcache is now secured against
|
|
* concurrent swapping to and from the slot. Verify that the
|
|
* swap entry hasn't been invalidated and recycled behind our
|
|
* backs (our zswap_entry reference doesn't prevent that), to
|
|
* avoid overwriting a new swap page with old compressed data.
|
|
*/
|
|
spin_lock(&tree->lock);
|
|
if (zswap_rb_search(&tree->rbroot, swp_offset(entry->swpentry)) != entry) {
|
|
spin_unlock(&tree->lock);
|
|
delete_from_swap_cache(page_folio(page));
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
spin_unlock(&tree->lock);
|
|
|
|
/* decompress */
|
|
acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
|
|
dlen = PAGE_SIZE;
|
|
|
|
src = zpool_map_handle(pool, entry->handle, ZPOOL_MM_RO);
|
|
if (!zpool_can_sleep_mapped(pool)) {
|
|
memcpy(tmp, src, entry->length);
|
|
src = tmp;
|
|
zpool_unmap_handle(pool, entry->handle);
|
|
}
|
|
|
|
mutex_lock(acomp_ctx->mutex);
|
|
sg_init_one(&input, src, entry->length);
|
|
sg_init_table(&output, 1);
|
|
sg_set_page(&output, page, PAGE_SIZE, 0);
|
|
acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
|
|
ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
|
|
dlen = acomp_ctx->req->dlen;
|
|
mutex_unlock(acomp_ctx->mutex);
|
|
|
|
if (!zpool_can_sleep_mapped(pool))
|
|
kfree(tmp);
|
|
else
|
|
zpool_unmap_handle(pool, entry->handle);
|
|
|
|
BUG_ON(ret);
|
|
BUG_ON(dlen != PAGE_SIZE);
|
|
|
|
/* page is up to date */
|
|
SetPageUptodate(page);
|
|
|
|
/* move it to the tail of the inactive list after end_writeback */
|
|
SetPageReclaim(page);
|
|
|
|
/* start writeback */
|
|
__swap_writepage(page, &wbc);
|
|
put_page(page);
|
|
|
|
return ret;
|
|
|
|
fail:
|
|
if (!zpool_can_sleep_mapped(pool))
|
|
kfree(tmp);
|
|
|
|
/*
|
|
* If we get here because the page is already in swapcache, a
|
|
* load may be happening concurrently. It is safe and okay to
|
|
* not free the entry. It is also okay to return !0.
|
|
*/
|
|
return ret;
|
|
}
|
|
|
|
static int zswap_is_page_same_filled(void *ptr, unsigned long *value)
|
|
{
|
|
unsigned long *page;
|
|
unsigned long val;
|
|
unsigned int pos, last_pos = PAGE_SIZE / sizeof(*page) - 1;
|
|
|
|
page = (unsigned long *)ptr;
|
|
val = page[0];
|
|
|
|
if (val != page[last_pos])
|
|
return 0;
|
|
|
|
for (pos = 1; pos < last_pos; pos++) {
|
|
if (val != page[pos])
|
|
return 0;
|
|
}
|
|
|
|
*value = val;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void zswap_fill_page(void *ptr, unsigned long value)
|
|
{
|
|
unsigned long *page;
|
|
|
|
page = (unsigned long *)ptr;
|
|
memset_l(page, value, PAGE_SIZE / sizeof(unsigned long));
|
|
}
|
|
|
|
bool zswap_store(struct folio *folio)
|
|
{
|
|
swp_entry_t swp = folio->swap;
|
|
int type = swp_type(swp);
|
|
pgoff_t offset = swp_offset(swp);
|
|
struct page *page = &folio->page;
|
|
struct zswap_tree *tree = zswap_trees[type];
|
|
struct zswap_entry *entry, *dupentry;
|
|
struct scatterlist input, output;
|
|
struct crypto_acomp_ctx *acomp_ctx;
|
|
struct obj_cgroup *objcg = NULL;
|
|
struct mem_cgroup *memcg = NULL;
|
|
struct zswap_pool *pool;
|
|
struct zpool *zpool;
|
|
unsigned int dlen = PAGE_SIZE;
|
|
unsigned long handle, value;
|
|
char *buf;
|
|
u8 *src, *dst;
|
|
gfp_t gfp;
|
|
int ret;
|
|
|
|
VM_WARN_ON_ONCE(!folio_test_locked(folio));
|
|
VM_WARN_ON_ONCE(!folio_test_swapcache(folio));
|
|
|
|
/* Large folios aren't supported */
|
|
if (folio_test_large(folio))
|
|
return false;
|
|
|
|
if (!zswap_enabled || !tree)
|
|
return false;
|
|
|
|
/*
|
|
* If this is a duplicate, it must be removed before attempting to store
|
|
* it, otherwise, if the store fails the old page won't be removed from
|
|
* the tree, and it might be written back overriding the new data.
|
|
*/
|
|
spin_lock(&tree->lock);
|
|
dupentry = zswap_rb_search(&tree->rbroot, offset);
|
|
if (dupentry) {
|
|
zswap_duplicate_entry++;
|
|
zswap_invalidate_entry(tree, dupentry);
|
|
}
|
|
spin_unlock(&tree->lock);
|
|
objcg = get_obj_cgroup_from_folio(folio);
|
|
if (objcg && !obj_cgroup_may_zswap(objcg)) {
|
|
memcg = get_mem_cgroup_from_objcg(objcg);
|
|
if (shrink_memcg(memcg)) {
|
|
mem_cgroup_put(memcg);
|
|
goto reject;
|
|
}
|
|
mem_cgroup_put(memcg);
|
|
}
|
|
|
|
/* reclaim space if needed */
|
|
if (zswap_is_full()) {
|
|
zswap_pool_limit_hit++;
|
|
zswap_pool_reached_full = true;
|
|
goto shrink;
|
|
}
|
|
|
|
if (zswap_pool_reached_full) {
|
|
if (!zswap_can_accept())
|
|
goto shrink;
|
|
else
|
|
zswap_pool_reached_full = false;
|
|
}
|
|
|
|
/* allocate entry */
|
|
entry = zswap_entry_cache_alloc(GFP_KERNEL, page_to_nid(page));
|
|
if (!entry) {
|
|
zswap_reject_kmemcache_fail++;
|
|
goto reject;
|
|
}
|
|
|
|
if (zswap_same_filled_pages_enabled) {
|
|
src = kmap_local_page(page);
|
|
if (zswap_is_page_same_filled(src, &value)) {
|
|
kunmap_local(src);
|
|
entry->swpentry = swp_entry(type, offset);
|
|
entry->length = 0;
|
|
entry->value = value;
|
|
atomic_inc(&zswap_same_filled_pages);
|
|
goto insert_entry;
|
|
}
|
|
kunmap_local(src);
|
|
}
|
|
|
|
if (!zswap_non_same_filled_pages_enabled)
|
|
goto freepage;
|
|
|
|
/* if entry is successfully added, it keeps the reference */
|
|
entry->pool = zswap_pool_current_get();
|
|
if (!entry->pool)
|
|
goto freepage;
|
|
|
|
if (objcg) {
|
|
memcg = get_mem_cgroup_from_objcg(objcg);
|
|
if (memcg_list_lru_alloc(memcg, &entry->pool->list_lru, GFP_KERNEL)) {
|
|
mem_cgroup_put(memcg);
|
|
goto put_pool;
|
|
}
|
|
mem_cgroup_put(memcg);
|
|
}
|
|
|
|
/* compress */
|
|
acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
|
|
|
|
mutex_lock(acomp_ctx->mutex);
|
|
|
|
dst = acomp_ctx->dstmem;
|
|
sg_init_table(&input, 1);
|
|
sg_set_page(&input, page, PAGE_SIZE, 0);
|
|
|
|
/* zswap_dstmem is of size (PAGE_SIZE * 2). Reflect same in sg_list */
|
|
sg_init_one(&output, dst, PAGE_SIZE * 2);
|
|
acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen);
|
|
/*
|
|
* it maybe looks a little bit silly that we send an asynchronous request,
|
|
* then wait for its completion synchronously. This makes the process look
|
|
* synchronous in fact.
|
|
* Theoretically, acomp supports users send multiple acomp requests in one
|
|
* acomp instance, then get those requests done simultaneously. but in this
|
|
* case, zswap actually does store and load page by page, there is no
|
|
* existing method to send the second page before the first page is done
|
|
* in one thread doing zwap.
|
|
* but in different threads running on different cpu, we have different
|
|
* acomp instance, so multiple threads can do (de)compression in parallel.
|
|
*/
|
|
ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
|
|
dlen = acomp_ctx->req->dlen;
|
|
|
|
if (ret) {
|
|
zswap_reject_compress_fail++;
|
|
goto put_dstmem;
|
|
}
|
|
|
|
/* store */
|
|
zpool = zswap_find_zpool(entry);
|
|
gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
|
|
if (zpool_malloc_support_movable(zpool))
|
|
gfp |= __GFP_HIGHMEM | __GFP_MOVABLE;
|
|
ret = zpool_malloc(zpool, dlen, gfp, &handle);
|
|
if (ret == -ENOSPC) {
|
|
zswap_reject_compress_poor++;
|
|
goto put_dstmem;
|
|
}
|
|
if (ret) {
|
|
zswap_reject_alloc_fail++;
|
|
goto put_dstmem;
|
|
}
|
|
buf = zpool_map_handle(zpool, handle, ZPOOL_MM_WO);
|
|
memcpy(buf, dst, dlen);
|
|
zpool_unmap_handle(zpool, handle);
|
|
mutex_unlock(acomp_ctx->mutex);
|
|
|
|
/* populate entry */
|
|
entry->swpentry = swp_entry(type, offset);
|
|
entry->handle = handle;
|
|
entry->length = dlen;
|
|
|
|
insert_entry:
|
|
entry->objcg = objcg;
|
|
if (objcg) {
|
|
obj_cgroup_charge_zswap(objcg, entry->length);
|
|
/* Account before objcg ref is moved to tree */
|
|
count_objcg_event(objcg, ZSWPOUT);
|
|
}
|
|
|
|
/* map */
|
|
spin_lock(&tree->lock);
|
|
/*
|
|
* A duplicate entry should have been removed at the beginning of this
|
|
* function. Since the swap entry should be pinned, if a duplicate is
|
|
* found again here it means that something went wrong in the swap
|
|
* cache.
|
|
*/
|
|
while (zswap_rb_insert(&tree->rbroot, entry, &dupentry) == -EEXIST) {
|
|
WARN_ON(1);
|
|
zswap_duplicate_entry++;
|
|
zswap_invalidate_entry(tree, dupentry);
|
|
}
|
|
if (entry->length) {
|
|
INIT_LIST_HEAD(&entry->lru);
|
|
zswap_lru_add(&entry->pool->list_lru, entry);
|
|
}
|
|
spin_unlock(&tree->lock);
|
|
|
|
/* update stats */
|
|
atomic_inc(&zswap_stored_pages);
|
|
zswap_update_total_size();
|
|
count_vm_event(ZSWPOUT);
|
|
|
|
return true;
|
|
|
|
put_dstmem:
|
|
mutex_unlock(acomp_ctx->mutex);
|
|
put_pool:
|
|
zswap_pool_put(entry->pool);
|
|
freepage:
|
|
zswap_entry_cache_free(entry);
|
|
reject:
|
|
if (objcg)
|
|
obj_cgroup_put(objcg);
|
|
return false;
|
|
|
|
shrink:
|
|
pool = zswap_pool_last_get();
|
|
if (pool && !queue_work(shrink_wq, &pool->shrink_work))
|
|
zswap_pool_put(pool);
|
|
goto reject;
|
|
}
|
|
|
|
bool zswap_load(struct folio *folio)
|
|
{
|
|
swp_entry_t swp = folio->swap;
|
|
int type = swp_type(swp);
|
|
pgoff_t offset = swp_offset(swp);
|
|
struct page *page = &folio->page;
|
|
struct zswap_tree *tree = zswap_trees[type];
|
|
struct zswap_entry *entry;
|
|
struct scatterlist input, output;
|
|
struct crypto_acomp_ctx *acomp_ctx;
|
|
u8 *src, *dst, *tmp;
|
|
struct zpool *zpool;
|
|
unsigned int dlen;
|
|
bool ret;
|
|
|
|
VM_WARN_ON_ONCE(!folio_test_locked(folio));
|
|
|
|
/* find */
|
|
spin_lock(&tree->lock);
|
|
entry = zswap_entry_find_get(&tree->rbroot, offset);
|
|
if (!entry) {
|
|
spin_unlock(&tree->lock);
|
|
return false;
|
|
}
|
|
spin_unlock(&tree->lock);
|
|
|
|
if (!entry->length) {
|
|
dst = kmap_local_page(page);
|
|
zswap_fill_page(dst, entry->value);
|
|
kunmap_local(dst);
|
|
ret = true;
|
|
goto stats;
|
|
}
|
|
|
|
zpool = zswap_find_zpool(entry);
|
|
if (!zpool_can_sleep_mapped(zpool)) {
|
|
tmp = kmalloc(entry->length, GFP_KERNEL);
|
|
if (!tmp) {
|
|
ret = false;
|
|
goto freeentry;
|
|
}
|
|
}
|
|
|
|
/* decompress */
|
|
dlen = PAGE_SIZE;
|
|
src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
|
|
|
|
if (!zpool_can_sleep_mapped(zpool)) {
|
|
memcpy(tmp, src, entry->length);
|
|
src = tmp;
|
|
zpool_unmap_handle(zpool, entry->handle);
|
|
}
|
|
|
|
acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
|
|
mutex_lock(acomp_ctx->mutex);
|
|
sg_init_one(&input, src, entry->length);
|
|
sg_init_table(&output, 1);
|
|
sg_set_page(&output, page, PAGE_SIZE, 0);
|
|
acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
|
|
if (crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait))
|
|
WARN_ON(1);
|
|
mutex_unlock(acomp_ctx->mutex);
|
|
|
|
if (zpool_can_sleep_mapped(zpool))
|
|
zpool_unmap_handle(zpool, entry->handle);
|
|
else
|
|
kfree(tmp);
|
|
|
|
ret = true;
|
|
stats:
|
|
count_vm_event(ZSWPIN);
|
|
if (entry->objcg)
|
|
count_objcg_event(entry->objcg, ZSWPIN);
|
|
freeentry:
|
|
spin_lock(&tree->lock);
|
|
if (ret && zswap_exclusive_loads_enabled) {
|
|
zswap_invalidate_entry(tree, entry);
|
|
folio_mark_dirty(folio);
|
|
} else if (entry->length) {
|
|
zswap_lru_del(&entry->pool->list_lru, entry);
|
|
zswap_lru_add(&entry->pool->list_lru, entry);
|
|
}
|
|
zswap_entry_put(tree, entry);
|
|
spin_unlock(&tree->lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
void zswap_invalidate(int type, pgoff_t offset)
|
|
{
|
|
struct zswap_tree *tree = zswap_trees[type];
|
|
struct zswap_entry *entry;
|
|
|
|
/* find */
|
|
spin_lock(&tree->lock);
|
|
entry = zswap_rb_search(&tree->rbroot, offset);
|
|
if (!entry) {
|
|
/* entry was written back */
|
|
spin_unlock(&tree->lock);
|
|
return;
|
|
}
|
|
zswap_invalidate_entry(tree, entry);
|
|
spin_unlock(&tree->lock);
|
|
}
|
|
|
|
void zswap_swapon(int type)
|
|
{
|
|
struct zswap_tree *tree;
|
|
|
|
tree = kzalloc(sizeof(*tree), GFP_KERNEL);
|
|
if (!tree) {
|
|
pr_err("alloc failed, zswap disabled for swap type %d\n", type);
|
|
return;
|
|
}
|
|
|
|
tree->rbroot = RB_ROOT;
|
|
spin_lock_init(&tree->lock);
|
|
zswap_trees[type] = tree;
|
|
}
|
|
|
|
void zswap_swapoff(int type)
|
|
{
|
|
struct zswap_tree *tree = zswap_trees[type];
|
|
struct zswap_entry *entry, *n;
|
|
|
|
if (!tree)
|
|
return;
|
|
|
|
/* walk the tree and free everything */
|
|
spin_lock(&tree->lock);
|
|
rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
|
|
zswap_free_entry(entry);
|
|
tree->rbroot = RB_ROOT;
|
|
spin_unlock(&tree->lock);
|
|
kfree(tree);
|
|
zswap_trees[type] = NULL;
|
|
}
|
|
|
|
/*********************************
|
|
* debugfs functions
|
|
**********************************/
|
|
#ifdef CONFIG_DEBUG_FS
|
|
#include <linux/debugfs.h>
|
|
|
|
static struct dentry *zswap_debugfs_root;
|
|
|
|
static int zswap_debugfs_init(void)
|
|
{
|
|
if (!debugfs_initialized())
|
|
return -ENODEV;
|
|
|
|
zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
|
|
|
|
debugfs_create_u64("pool_limit_hit", 0444,
|
|
zswap_debugfs_root, &zswap_pool_limit_hit);
|
|
debugfs_create_u64("reject_reclaim_fail", 0444,
|
|
zswap_debugfs_root, &zswap_reject_reclaim_fail);
|
|
debugfs_create_u64("reject_alloc_fail", 0444,
|
|
zswap_debugfs_root, &zswap_reject_alloc_fail);
|
|
debugfs_create_u64("reject_kmemcache_fail", 0444,
|
|
zswap_debugfs_root, &zswap_reject_kmemcache_fail);
|
|
debugfs_create_u64("reject_compress_fail", 0444,
|
|
zswap_debugfs_root, &zswap_reject_compress_fail);
|
|
debugfs_create_u64("reject_compress_poor", 0444,
|
|
zswap_debugfs_root, &zswap_reject_compress_poor);
|
|
debugfs_create_u64("written_back_pages", 0444,
|
|
zswap_debugfs_root, &zswap_written_back_pages);
|
|
debugfs_create_u64("duplicate_entry", 0444,
|
|
zswap_debugfs_root, &zswap_duplicate_entry);
|
|
debugfs_create_u64("pool_total_size", 0444,
|
|
zswap_debugfs_root, &zswap_pool_total_size);
|
|
debugfs_create_atomic_t("stored_pages", 0444,
|
|
zswap_debugfs_root, &zswap_stored_pages);
|
|
debugfs_create_atomic_t("same_filled_pages", 0444,
|
|
zswap_debugfs_root, &zswap_same_filled_pages);
|
|
|
|
return 0;
|
|
}
|
|
#else
|
|
static int zswap_debugfs_init(void)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
/*********************************
|
|
* module init and exit
|
|
**********************************/
|
|
static int zswap_setup(void)
|
|
{
|
|
struct zswap_pool *pool;
|
|
int ret;
|
|
|
|
zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
|
|
if (!zswap_entry_cache) {
|
|
pr_err("entry cache creation failed\n");
|
|
goto cache_fail;
|
|
}
|
|
|
|
ret = cpuhp_setup_state(CPUHP_MM_ZSWP_MEM_PREPARE, "mm/zswap:prepare",
|
|
zswap_dstmem_prepare, zswap_dstmem_dead);
|
|
if (ret) {
|
|
pr_err("dstmem alloc failed\n");
|
|
goto dstmem_fail;
|
|
}
|
|
|
|
ret = cpuhp_setup_state_multi(CPUHP_MM_ZSWP_POOL_PREPARE,
|
|
"mm/zswap_pool:prepare",
|
|
zswap_cpu_comp_prepare,
|
|
zswap_cpu_comp_dead);
|
|
if (ret)
|
|
goto hp_fail;
|
|
|
|
pool = __zswap_pool_create_fallback();
|
|
if (pool) {
|
|
pr_info("loaded using pool %s/%s\n", pool->tfm_name,
|
|
zpool_get_type(pool->zpools[0]));
|
|
list_add(&pool->list, &zswap_pools);
|
|
zswap_has_pool = true;
|
|
} else {
|
|
pr_err("pool creation failed\n");
|
|
zswap_enabled = false;
|
|
}
|
|
|
|
shrink_wq = create_workqueue("zswap-shrink");
|
|
if (!shrink_wq)
|
|
goto fallback_fail;
|
|
|
|
if (zswap_debugfs_init())
|
|
pr_warn("debugfs initialization failed\n");
|
|
zswap_init_state = ZSWAP_INIT_SUCCEED;
|
|
return 0;
|
|
|
|
fallback_fail:
|
|
if (pool)
|
|
zswap_pool_destroy(pool);
|
|
hp_fail:
|
|
cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
|
|
dstmem_fail:
|
|
kmem_cache_destroy(zswap_entry_cache);
|
|
cache_fail:
|
|
/* if built-in, we aren't unloaded on failure; don't allow use */
|
|
zswap_init_state = ZSWAP_INIT_FAILED;
|
|
zswap_enabled = false;
|
|
return -ENOMEM;
|
|
}
|
|
|
|
static int __init zswap_init(void)
|
|
{
|
|
if (!zswap_enabled)
|
|
return 0;
|
|
return zswap_setup();
|
|
}
|
|
/* must be late so crypto has time to come up */
|
|
late_initcall(zswap_init);
|
|
|
|
MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
|
|
MODULE_DESCRIPTION("Compressed cache for swap pages");
|