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259043e3b7
If CONFIG_ZSWAP is set to N, it means zswap cannot be enabled.
zswap_never_enabled() should return true.
The only effect of this issue is that with Barry's latest large folio
swapin patches for zram ("mm: support mTHP swap-in for zRAM-like
swapfile"), we will always fallback to order-0 swapin, even mistakenly
when !CONFIG_ZSWAP.
Basically this bug makes Barry's in progress patches not work at all.
The API was created to inform the mm core that zswap has never been
enabled, allowing the mm core to perform mTHP swap-in. This is a
transitional solution until zswap supports mTHP. If zswap has been
enabled, performing mTHP swap-in will result in corrupted data. You
may find the answer in the mTHP swap-in series:
https://lore.kernel.org/linux-mm/CAJD7tkZ4FQr6HZpduOdvmqgg_-whuZYE-Bz5O2t6yzw6Yg+v1A@mail.gmail.com/
Link: https://lkml.kernel.org/r/20240629232231.42394-1-21cnbao@gmail.com
Fixes: 0300e17d67c3 ("mm: zswap: add zswap_never_enabled()")
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Chris Li <chrisl@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
77 lines
1.8 KiB
C
77 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_ZSWAP_H
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#define _LINUX_ZSWAP_H
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#include <linux/types.h>
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#include <linux/mm_types.h>
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struct lruvec;
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extern atomic_t zswap_stored_pages;
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#ifdef CONFIG_ZSWAP
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struct zswap_lruvec_state {
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/*
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* Number of pages in zswap that should be protected from the shrinker.
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* This number is an estimate of the following counts:
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*
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* a) Recent page faults.
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* b) Recent insertion to the zswap LRU. This includes new zswap stores,
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* as well as recent zswap LRU rotations.
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*
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* These pages are likely to be warm, and might incur IO if the are written
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* to swap.
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*/
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atomic_long_t nr_zswap_protected;
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};
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unsigned long zswap_total_pages(void);
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bool zswap_store(struct folio *folio);
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bool zswap_load(struct folio *folio);
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void zswap_invalidate(swp_entry_t swp);
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int zswap_swapon(int type, unsigned long nr_pages);
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void zswap_swapoff(int type);
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void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg);
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void zswap_lruvec_state_init(struct lruvec *lruvec);
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void zswap_folio_swapin(struct folio *folio);
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bool zswap_is_enabled(void);
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bool zswap_never_enabled(void);
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#else
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struct zswap_lruvec_state {};
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static inline bool zswap_store(struct folio *folio)
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{
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return false;
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}
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static inline bool zswap_load(struct folio *folio)
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{
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return false;
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}
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static inline void zswap_invalidate(swp_entry_t swp) {}
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static inline int zswap_swapon(int type, unsigned long nr_pages)
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{
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return 0;
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}
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static inline void zswap_swapoff(int type) {}
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static inline void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg) {}
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static inline void zswap_lruvec_state_init(struct lruvec *lruvec) {}
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static inline void zswap_folio_swapin(struct folio *folio) {}
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static inline bool zswap_is_enabled(void)
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{
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return false;
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}
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static inline bool zswap_never_enabled(void)
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{
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return true;
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}
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#endif
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#endif /* _LINUX_ZSWAP_H */
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