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linux-stable/include/linux/swap.h
Peter Xu 679d103319 mm: introduce PTE_MARKER swap entry 
Patch series "userfaultfd-wp: Support shmem and hugetlbfs", v8.


Overview
========

Userfaultfd-wp anonymous support was merged two years ago.  There're quite
a few applications that started to leverage this capability either to take
snapshots for user-app memory, or use it for full user controled swapping.

This series tries to complete the feature for uffd-wp so as to cover all
the RAM-based memory types.  So far uffd-wp is the only missing piece of
the rest features (uffd-missing & uffd-minor mode).

One major reason to do so is that anonymous pages are sometimes not
satisfying the need of applications, and there're growing users of either
shmem and hugetlbfs for either sharing purpose (e.g., sharing guest mem
between hypervisor process and device emulation process, shmem local live
migration for upgrades), or for performance on tlb hits.

All these mean that if a uffd-wp app wants to switch to any of the memory
types, it'll stop working.  I think it's worthwhile to have the kernel to
cover all these aspects.

This series chose to protect pages in pte level not page level.

One major reason is safety.  I have no idea how we could make it safe if
any of the uffd-privileged app can wr-protect a page that any other
application can use.  It means this app can block any process potentially
for any time it wants.

The other reason is that it aligns very well with not only the anonymous
uffd-wp solution, but also uffd as a whole.  For example, userfaultfd is
implemented fundamentally based on VMAs.  We set flags to VMAs showing the
status of uffd tracking.  For another per-page based protection solution,
it'll be crossing the fundation line on VMA-based, and it could simply be
too far away already from what's called userfaultfd.

PTE markers
===========

The patchset is based on the idea called PTE markers.  It was discussed in
one of the mm alignment sessions, proposed starting from v6, and this is
the 2nd version of it using PTE marker idea.

PTE marker is a new type of swap entry that is ony applicable to file
backed memories like shmem and hugetlbfs.  It's used to persist some
pte-level information even if the original present ptes in pgtable are
zapped.

Logically pte markers can store more than uffd-wp information, but so far
only one bit is used for uffd-wp purpose.  When the pte marker is
installed with uffd-wp bit set, it means this pte is wr-protected by uffd.

It solves the problem on e.g.  file-backed memory mapped ptes got zapped
due to any reason (e.g.  thp split, or swapped out), we can still keep the
wr-protect information in the ptes.  Then when the page fault triggers
again, we'll know this pte is wr-protected so we can treat the pte the
same as a normal uffd wr-protected pte.

The extra information is encoded into the swap entry, or swp_offset to be
explicit, with the swp_type being PTE_MARKER.  So far uffd-wp only uses
one bit out of the swap entry, the rest bits of swp_offset are still
reserved for other purposes.

There're two configs to enable/disable PTE markers:

  CONFIG_PTE_MARKER
  CONFIG_PTE_MARKER_UFFD_WP

We can set !PTE_MARKER to completely disable all the PTE markers, along
with uffd-wp support.  I made two config so we can also enable PTE marker
but disable uffd-wp file-backed for other purposes.  At the end of current
series, I'll enable CONFIG_PTE_MARKER by default, but that patch is
standalone and if anyone worries about having it by default, we can also
consider turn it off by dropping that oneliner patch.  So far I don't see
a huge risk of doing so, so I kept that patch.

In most cases, PTE markers should be treated as none ptes.  It is because
that unlike most of the other swap entry types, there's no PFN or block
offset information encoded into PTE markers but some extra well-defined
bits showing the status of the pte.  These bits should only be used as
extra data when servicing an upcoming page fault, and then we behave as if
it's a none pte.

I did spend a lot of time observing all the pte_none() users this time. 
It is indeed a challenge because there're a lot, and I hope I didn't miss
a single of them when we should take care of pte markers.  Luckily, I
don't think it'll need to be considered in many cases, for example: boot
code, arch code (especially non-x86), kernel-only page handlings (e.g. 
CPA), or device driver codes when we're tackling with pure PFN mappings.

I introduced pte_none_mostly() in this series when we need to handle pte
markers the same as none pte, the "mostly" is the other way to write
"either none pte or a pte marker".

I didn't replace pte_none() to cover pte markers for below reasons:

  - Very rare case of pte_none() callers will handle pte markers.  E.g., all
    the kernel pages do not require knowledge of pte markers.  So we don't
    pollute the major use cases.

  - Unconditionally change pte_none() semantics could confuse people, because
    pte_none() existed for so long a time.

  - Unconditionally change pte_none() semantics could make pte_none() slower
    even if in many cases pte markers do not exist.

  - There're cases where we'd like to handle pte markers differntly from
    pte_none(), so a full replace is also impossible.  E.g. khugepaged should
    still treat pte markers as normal swap ptes rather than none ptes, because
    pte markers will always need a fault-in to merge the marker with a valid
    pte.  Or the smap code will need to parse PTE markers not none ptes.

Patch Layout
============

Introducing PTE marker and uffd-wp bit in PTE marker:

  mm: Introduce PTE_MARKER swap entry
  mm: Teach core mm about pte markers
  mm: Check against orig_pte for finish_fault()
  mm/uffd: PTE_MARKER_UFFD_WP

Adding support for shmem uffd-wp:

  mm/shmem: Take care of UFFDIO_COPY_MODE_WP
  mm/shmem: Handle uffd-wp special pte in page fault handler
  mm/shmem: Persist uffd-wp bit across zapping for file-backed
  mm/shmem: Allow uffd wr-protect none pte for file-backed mem
  mm/shmem: Allows file-back mem to be uffd wr-protected on thps
  mm/shmem: Handle uffd-wp during fork()

Adding support for hugetlbfs uffd-wp:

  mm/hugetlb: Introduce huge pte version of uffd-wp helpers
  mm/hugetlb: Hook page faults for uffd write protection
  mm/hugetlb: Take care of UFFDIO_COPY_MODE_WP
  mm/hugetlb: Handle UFFDIO_WRITEPROTECT
  mm/hugetlb: Handle pte markers in page faults
  mm/hugetlb: Allow uffd wr-protect none ptes
  mm/hugetlb: Only drop uffd-wp special pte if required
  mm/hugetlb: Handle uffd-wp during fork()

Misc handling on the rest mm for uffd-wp file-backed:

  mm/khugepaged: Don't recycle vma pgtable if uffd-wp registered
  mm/pagemap: Recognize uffd-wp bit for shmem/hugetlbfs

Enabling of uffd-wp on file-backed memory:

  mm/uffd: Enable write protection for shmem & hugetlbfs
  mm: Enable PTE markers by default
  selftests/uffd: Enable uffd-wp for shmem/hugetlbfs

Tests
=====

- Compile test on x86_64 and aarch64 on different configs
- Kernel selftests
- uffd-test [0]
- Umapsort [1,2] test for shmem/hugetlb, with swap on/off

[0] https://github.com/xzpeter/clibs/tree/master/uffd-test
[1] https://github.com/xzpeter/umap-apps/tree/peter
[2] https://github.com/xzpeter/umap/tree/peter-shmem-hugetlbfs


This patch (of 23):

Introduces a new swap entry type called PTE_MARKER.  It can be installed
for any pte that maps a file-backed memory when the pte is temporarily
zapped, so as to maintain per-pte information.

The information that kept in the pte is called a "marker".  Here we define
the marker as "unsigned long" just to match pgoff_t, however it will only
work if it still fits in swp_offset(), which is e.g.  currently 58 bits on
x86_64.

A new config CONFIG_PTE_MARKER is introduced too; it's by default off.  A
bunch of helpers are defined altogether to service the rest of the pte
marker code.

[peterx@redhat.com: fixup]
  Link: https://lkml.kernel.org/r/Yk2rdB7SXZf+2BDF@xz-m1.local
Link: https://lkml.kernel.org/r/20220405014646.13522-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20220405014646.13522-2-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-13 07:20:09 -07:00

692 lines
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_SWAP_H
#define _LINUX_SWAP_H
#include <linux/spinlock.h>
#include <linux/linkage.h>
#include <linux/mmzone.h>
#include <linux/list.h>
#include <linux/memcontrol.h>
#include <linux/sched.h>
#include <linux/node.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/atomic.h>
#include <linux/page-flags.h>
#include <uapi/linux/mempolicy.h>
#include <asm/page.h>
struct notifier_block;
struct bio;
struct pagevec;
#define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
#define SWAP_FLAG_PRIO_MASK 0x7fff
#define SWAP_FLAG_PRIO_SHIFT 0
#define SWAP_FLAG_DISCARD 0x10000 /* enable discard for swap */
#define SWAP_FLAG_DISCARD_ONCE 0x20000 /* discard swap area at swapon-time */
#define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
#define SWAP_FLAGS_VALID (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
SWAP_FLAG_DISCARD_PAGES)
#define SWAP_BATCH 64
static inline int current_is_kswapd(void)
{
return current->flags & PF_KSWAPD;
}
/*
* MAX_SWAPFILES defines the maximum number of swaptypes: things which can
* be swapped to. The swap type and the offset into that swap type are
* encoded into pte's and into pgoff_t's in the swapcache. Using five bits
* for the type means that the maximum number of swapcache pages is 27 bits
* on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
* the type/offset into the pte as 5/27 as well.
*/
#define MAX_SWAPFILES_SHIFT 5
/*
* Use some of the swap files numbers for other purposes. This
* is a convenient way to hook into the VM to trigger special
* actions on faults.
*/
/*
* PTE markers are used to persist information onto PTEs that are mapped with
* file-backed memories. As its name "PTE" hints, it should only be applied to
* the leaves of pgtables.
*/
#ifdef CONFIG_PTE_MARKER
#define SWP_PTE_MARKER_NUM 1
#define SWP_PTE_MARKER (MAX_SWAPFILES + SWP_HWPOISON_NUM + \
SWP_MIGRATION_NUM + SWP_DEVICE_NUM)
#else
#define SWP_PTE_MARKER_NUM 0
#endif
/*
* Unaddressable device memory support. See include/linux/hmm.h and
* Documentation/vm/hmm.rst. Short description is we need struct pages for
* device memory that is unaddressable (inaccessible) by CPU, so that we can
* migrate part of a process memory to device memory.
*
* When a page is migrated from CPU to device, we set the CPU page table entry
* to a special SWP_DEVICE_{READ|WRITE} entry.
*
* When a page is mapped by the device for exclusive access we set the CPU page
* table entries to special SWP_DEVICE_EXCLUSIVE_* entries.
*/
#ifdef CONFIG_DEVICE_PRIVATE
#define SWP_DEVICE_NUM 4
#define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
#define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
#define SWP_DEVICE_EXCLUSIVE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+2)
#define SWP_DEVICE_EXCLUSIVE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+3)
#else
#define SWP_DEVICE_NUM 0
#endif
/*
* Page migration support.
*
* SWP_MIGRATION_READ_EXCLUSIVE is only applicable to anonymous pages and
* indicates that the referenced (part of) an anonymous page is exclusive to
* a single process. For SWP_MIGRATION_WRITE, that information is implicit:
* (part of) an anonymous page that are mapped writable are exclusive to a
* single process.
*/
#ifdef CONFIG_MIGRATION
#define SWP_MIGRATION_NUM 3
#define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
#define SWP_MIGRATION_READ_EXCLUSIVE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 2)
#else
#define SWP_MIGRATION_NUM 0
#endif
/*
* Handling of hardware poisoned pages with memory corruption.
*/
#ifdef CONFIG_MEMORY_FAILURE
#define SWP_HWPOISON_NUM 1
#define SWP_HWPOISON MAX_SWAPFILES
#else
#define SWP_HWPOISON_NUM 0
#endif
#define MAX_SWAPFILES \
((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
SWP_MIGRATION_NUM - SWP_HWPOISON_NUM - SWP_PTE_MARKER_NUM)
/*
* Magic header for a swap area. The first part of the union is
* what the swap magic looks like for the old (limited to 128MB)
* swap area format, the second part of the union adds - in the
* old reserved area - some extra information. Note that the first
* kilobyte is reserved for boot loader or disk label stuff...
*
* Having the magic at the end of the PAGE_SIZE makes detecting swap
* areas somewhat tricky on machines that support multiple page sizes.
* For 2.5 we'll probably want to move the magic to just beyond the
* bootbits...
*/
union swap_header {
struct {
char reserved[PAGE_SIZE - 10];
char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
} magic;
struct {
char bootbits[1024]; /* Space for disklabel etc. */
__u32 version;
__u32 last_page;
__u32 nr_badpages;
unsigned char sws_uuid[16];
unsigned char sws_volume[16];
__u32 padding[117];
__u32 badpages[1];
} info;
};
/*
* current->reclaim_state points to one of these when a task is running
* memory reclaim
*/
struct reclaim_state {
unsigned long reclaimed_slab;
};
#ifdef __KERNEL__
struct address_space;
struct sysinfo;
struct writeback_control;
struct zone;
/*
* A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
* disk blocks. A list of swap extents maps the entire swapfile. (Where the
* term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
* from setup, they're handled identically.
*
* We always assume that blocks are of size PAGE_SIZE.
*/
struct swap_extent {
struct rb_node rb_node;
pgoff_t start_page;
pgoff_t nr_pages;
sector_t start_block;
};
/*
* Max bad pages in the new format..
*/
#define MAX_SWAP_BADPAGES \
((offsetof(union swap_header, magic.magic) - \
offsetof(union swap_header, info.badpages)) / sizeof(int))
enum {
SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */
SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */
SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */
SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */
SWP_BLKDEV = (1 << 6), /* its a block device */
SWP_ACTIVATED = (1 << 7), /* set after swap_activate success */
SWP_FS_OPS = (1 << 8), /* swapfile operations go through fs */
SWP_AREA_DISCARD = (1 << 9), /* single-time swap area discards */
SWP_PAGE_DISCARD = (1 << 10), /* freed swap page-cluster discards */
SWP_STABLE_WRITES = (1 << 11), /* no overwrite PG_writeback pages */
SWP_SYNCHRONOUS_IO = (1 << 12), /* synchronous IO is efficient */
/* add others here before... */
SWP_SCANNING = (1 << 14), /* refcount in scan_swap_map */
};
#define SWAP_CLUSTER_MAX 32UL
#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
/* Bit flag in swap_map */
#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
#define COUNT_CONTINUED 0x80 /* Flag swap_map continuation for full count */
/* Special value in first swap_map */
#define SWAP_MAP_MAX 0x3e /* Max count */
#define SWAP_MAP_BAD 0x3f /* Note page is bad */
#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs */
/* Special value in each swap_map continuation */
#define SWAP_CONT_MAX 0x7f /* Max count */
/*
* We use this to track usage of a cluster. A cluster is a block of swap disk
* space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
* free clusters are organized into a list. We fetch an entry from the list to
* get a free cluster.
*
* The data field stores next cluster if the cluster is free or cluster usage
* counter otherwise. The flags field determines if a cluster is free. This is
* protected by swap_info_struct.lock.
*/
struct swap_cluster_info {
spinlock_t lock; /*
* Protect swap_cluster_info fields
* and swap_info_struct->swap_map
* elements correspond to the swap
* cluster
*/
unsigned int data:24;
unsigned int flags:8;
};
#define CLUSTER_FLAG_FREE 1 /* This cluster is free */
#define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
#define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
/*
* We assign a cluster to each CPU, so each CPU can allocate swap entry from
* its own cluster and swapout sequentially. The purpose is to optimize swapout
* throughput.
*/
struct percpu_cluster {
struct swap_cluster_info index; /* Current cluster index */
unsigned int next; /* Likely next allocation offset */
};
struct swap_cluster_list {
struct swap_cluster_info head;
struct swap_cluster_info tail;
};
/*
* The in-memory structure used to track swap areas.
*/
struct swap_info_struct {
struct percpu_ref users; /* indicate and keep swap device valid. */
unsigned long flags; /* SWP_USED etc: see above */
signed short prio; /* swap priority of this type */
struct plist_node list; /* entry in swap_active_head */
signed char type; /* strange name for an index */
unsigned int max; /* extent of the swap_map */
unsigned char *swap_map; /* vmalloc'ed array of usage counts */
struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
struct swap_cluster_list free_clusters; /* free clusters list */
unsigned int lowest_bit; /* index of first free in swap_map */
unsigned int highest_bit; /* index of last free in swap_map */
unsigned int pages; /* total of usable pages of swap */
unsigned int inuse_pages; /* number of those currently in use */
unsigned int cluster_next; /* likely index for next allocation */
unsigned int cluster_nr; /* countdown to next cluster search */
unsigned int __percpu *cluster_next_cpu; /*percpu index for next allocation */
struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
struct rb_root swap_extent_root;/* root of the swap extent rbtree */
struct block_device *bdev; /* swap device or bdev of swap file */
struct file *swap_file; /* seldom referenced */
unsigned int old_block_size; /* seldom referenced */
struct completion comp; /* seldom referenced */
#ifdef CONFIG_FRONTSWAP
unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
atomic_t frontswap_pages; /* frontswap pages in-use counter */
#endif
spinlock_t lock; /*
* protect map scan related fields like
* swap_map, lowest_bit, highest_bit,
* inuse_pages, cluster_next,
* cluster_nr, lowest_alloc,
* highest_alloc, free/discard cluster
* list. other fields are only changed
* at swapon/swapoff, so are protected
* by swap_lock. changing flags need
* hold this lock and swap_lock. If
* both locks need hold, hold swap_lock
* first.
*/
spinlock_t cont_lock; /*
* protect swap count continuation page
* list.
*/
struct work_struct discard_work; /* discard worker */
struct swap_cluster_list discard_clusters; /* discard clusters list */
struct plist_node avail_lists[]; /*
* entries in swap_avail_heads, one
* entry per node.
* Must be last as the number of the
* array is nr_node_ids, which is not
* a fixed value so have to allocate
* dynamically.
* And it has to be an array so that
* plist_for_each_* can work.
*/
};
#ifdef CONFIG_64BIT
#define SWAP_RA_ORDER_CEILING 5
#else
/* Avoid stack overflow, because we need to save part of page table */
#define SWAP_RA_ORDER_CEILING 3
#define SWAP_RA_PTE_CACHE_SIZE (1 << SWAP_RA_ORDER_CEILING)
#endif
struct vma_swap_readahead {
unsigned short win;
unsigned short offset;
unsigned short nr_pte;
#ifdef CONFIG_64BIT
pte_t *ptes;
#else
pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
#endif
};
static inline swp_entry_t folio_swap_entry(struct folio *folio)
{
swp_entry_t entry = { .val = page_private(&folio->page) };
return entry;
}
/* linux/mm/workingset.c */
void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg);
void workingset_refault(struct folio *folio, void *shadow);
void workingset_activation(struct folio *folio);
/* Only track the nodes of mappings with shadow entries */
void workingset_update_node(struct xa_node *node);
extern struct list_lru shadow_nodes;
#define mapping_set_update(xas, mapping) do { \
if (!dax_mapping(mapping) && !shmem_mapping(mapping)) { \
xas_set_update(xas, workingset_update_node); \
xas_set_lru(xas, &shadow_nodes); \
} \
} while (0)
/* linux/mm/page_alloc.c */
extern unsigned long totalreserve_pages;
/* Definition of global_zone_page_state not available yet */
#define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
/* linux/mm/swap.c */
extern void lru_note_cost(struct lruvec *lruvec, bool file,
unsigned int nr_pages);
extern void lru_note_cost_folio(struct folio *);
extern void folio_add_lru(struct folio *);
extern void lru_cache_add(struct page *);
void mark_page_accessed(struct page *);
void folio_mark_accessed(struct folio *);
extern atomic_t lru_disable_count;
static inline bool lru_cache_disabled(void)
{
return atomic_read(&lru_disable_count);
}
static inline void lru_cache_enable(void)
{
atomic_dec(&lru_disable_count);
}
extern void lru_cache_disable(void);
extern void lru_add_drain(void);
extern void lru_add_drain_cpu(int cpu);
extern void lru_add_drain_cpu_zone(struct zone *zone);
extern void lru_add_drain_all(void);
extern void deactivate_page(struct page *page);
extern void mark_page_lazyfree(struct page *page);
extern void swap_setup(void);
extern void lru_cache_add_inactive_or_unevictable(struct page *page,
struct vm_area_struct *vma);
/* linux/mm/vmscan.c */
extern unsigned long zone_reclaimable_pages(struct zone *zone);
extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
gfp_t gfp_mask, nodemask_t *mask);
extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
unsigned long nr_pages,
gfp_t gfp_mask,
bool may_swap);
extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
gfp_t gfp_mask, bool noswap,
pg_data_t *pgdat,
unsigned long *nr_scanned);
extern unsigned long shrink_all_memory(unsigned long nr_pages);
extern int vm_swappiness;
long remove_mapping(struct address_space *mapping, struct folio *folio);
extern unsigned long reclaim_pages(struct list_head *page_list);
#ifdef CONFIG_NUMA
extern int node_reclaim_mode;
extern int sysctl_min_unmapped_ratio;
extern int sysctl_min_slab_ratio;
#else
#define node_reclaim_mode 0
#endif
static inline bool node_reclaim_enabled(void)
{
/* Is any node_reclaim_mode bit set? */
return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP);
}
extern void check_move_unevictable_pages(struct pagevec *pvec);
extern void kswapd_run(int nid);
extern void kswapd_stop(int nid);
#ifdef CONFIG_SWAP
int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
unsigned long nr_pages, sector_t start_block);
int generic_swapfile_activate(struct swap_info_struct *, struct file *,
sector_t *);
static inline unsigned long total_swapcache_pages(void)
{
return global_node_page_state(NR_SWAPCACHE);
}
extern void free_page_and_swap_cache(struct page *);
extern void free_pages_and_swap_cache(struct page **, int);
/* linux/mm/swapfile.c */
extern atomic_long_t nr_swap_pages;
extern long total_swap_pages;
extern atomic_t nr_rotate_swap;
extern bool has_usable_swap(void);
/* Swap 50% full? Release swapcache more aggressively.. */
static inline bool vm_swap_full(void)
{
return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
}
static inline long get_nr_swap_pages(void)
{
return atomic_long_read(&nr_swap_pages);
}
extern void si_swapinfo(struct sysinfo *);
extern swp_entry_t get_swap_page(struct page *page);
extern void put_swap_page(struct page *page, swp_entry_t entry);
extern swp_entry_t get_swap_page_of_type(int);
extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
extern int add_swap_count_continuation(swp_entry_t, gfp_t);
extern void swap_shmem_alloc(swp_entry_t);
extern int swap_duplicate(swp_entry_t);
extern int swapcache_prepare(swp_entry_t);
extern void swap_free(swp_entry_t);
extern void swapcache_free_entries(swp_entry_t *entries, int n);
extern int free_swap_and_cache(swp_entry_t);
int swap_type_of(dev_t device, sector_t offset);
int find_first_swap(dev_t *device);
extern unsigned int count_swap_pages(int, int);
extern sector_t swapdev_block(int, pgoff_t);
extern int page_swapcount(struct page *);
extern int __swap_count(swp_entry_t entry);
extern int __swp_swapcount(swp_entry_t entry);
extern int swp_swapcount(swp_entry_t entry);
extern struct swap_info_struct *page_swap_info(struct page *);
extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
extern int try_to_free_swap(struct page *);
struct backing_dev_info;
extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
extern void exit_swap_address_space(unsigned int type);
extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
sector_t swap_page_sector(struct page *page);
static inline void put_swap_device(struct swap_info_struct *si)
{
percpu_ref_put(&si->users);
}
#else /* CONFIG_SWAP */
static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
{
return NULL;
}
static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
{
return NULL;
}
static inline void put_swap_device(struct swap_info_struct *si)
{
}
#define get_nr_swap_pages() 0L
#define total_swap_pages 0L
#define total_swapcache_pages() 0UL
#define vm_swap_full() 0
#define si_swapinfo(val) \
do { (val)->freeswap = (val)->totalswap = 0; } while (0)
/* only sparc can not include linux/pagemap.h in this file
* so leave put_page and release_pages undeclared... */
#define free_page_and_swap_cache(page) \
put_page(page)
#define free_pages_and_swap_cache(pages, nr) \
release_pages((pages), (nr));
/* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */
#define free_swap_and_cache(e) is_pfn_swap_entry(e)
static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
{
return 0;
}
static inline void swap_shmem_alloc(swp_entry_t swp)
{
}
static inline int swap_duplicate(swp_entry_t swp)
{
return 0;
}
static inline void swap_free(swp_entry_t swp)
{
}
static inline void put_swap_page(struct page *page, swp_entry_t swp)
{
}
static inline int page_swapcount(struct page *page)
{
return 0;
}
static inline int __swap_count(swp_entry_t entry)
{
return 0;
}
static inline int __swp_swapcount(swp_entry_t entry)
{
return 0;
}
static inline int swp_swapcount(swp_entry_t entry)
{
return 0;
}
static inline int try_to_free_swap(struct page *page)
{
return 0;
}
static inline swp_entry_t get_swap_page(struct page *page)
{
swp_entry_t entry;
entry.val = 0;
return entry;
}
static inline int add_swap_extent(struct swap_info_struct *sis,
unsigned long start_page,
unsigned long nr_pages, sector_t start_block)
{
return -EINVAL;
}
#endif /* CONFIG_SWAP */
#ifdef CONFIG_THP_SWAP
extern int split_swap_cluster(swp_entry_t entry);
#else
static inline int split_swap_cluster(swp_entry_t entry)
{
return 0;
}
#endif
#ifdef CONFIG_MEMCG
static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
{
/* Cgroup2 doesn't have per-cgroup swappiness */
if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
return vm_swappiness;
/* root ? */
if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg))
return vm_swappiness;
return memcg->swappiness;
}
#else
static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
{
return vm_swappiness;
}
#endif
#if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
extern void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask);
static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
{
if (mem_cgroup_disabled())
return;
__cgroup_throttle_swaprate(page, gfp_mask);
}
#else
static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
{
}
#endif
#ifdef CONFIG_MEMCG_SWAP
void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry);
extern int __mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
static inline int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
{
if (mem_cgroup_disabled())
return 0;
return __mem_cgroup_try_charge_swap(page, entry);
}
extern void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
{
if (mem_cgroup_disabled())
return;
__mem_cgroup_uncharge_swap(entry, nr_pages);
}
extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
extern bool mem_cgroup_swap_full(struct page *page);
#else
static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
{
}
static inline int mem_cgroup_try_charge_swap(struct page *page,
swp_entry_t entry)
{
return 0;
}
static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
unsigned int nr_pages)
{
}
static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
{
return get_nr_swap_pages();
}
static inline bool mem_cgroup_swap_full(struct page *page)
{
return vm_swap_full();
}
#endif
#endif /* __KERNEL__*/
#endif /* _LINUX_SWAP_H */
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