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       1                 :            : /* SPDX-License-Identifier: GPL-2.0 */
       2                 :            : #ifndef _LINUX_COMPACTION_H
       3                 :            : #define _LINUX_COMPACTION_H
       4                 :            : 
       5                 :            : /*
       6                 :            :  * Determines how hard direct compaction should try to succeed.
       7                 :            :  * Lower value means higher priority, analogically to reclaim priority.
       8                 :            :  */
       9                 :            : enum compact_priority {
      10                 :            :         COMPACT_PRIO_SYNC_FULL,
      11                 :            :         MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL,
      12                 :            :         COMPACT_PRIO_SYNC_LIGHT,
      13                 :            :         MIN_COMPACT_COSTLY_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
      14                 :            :         DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
      15                 :            :         COMPACT_PRIO_ASYNC,
      16                 :            :         INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
      17                 :            : };
      18                 :            : 
      19                 :            : /* Return values for compact_zone() and try_to_compact_pages() */
      20                 :            : /* When adding new states, please adjust include/trace/events/compaction.h */
      21                 :            : enum compact_result {
      22                 :            :         /* For more detailed tracepoint output - internal to compaction */
      23                 :            :         COMPACT_NOT_SUITABLE_ZONE,
      24                 :            :         /*
      25                 :            :          * compaction didn't start as it was not possible or direct reclaim
      26                 :            :          * was more suitable
      27                 :            :          */
      28                 :            :         COMPACT_SKIPPED,
      29                 :            :         /* compaction didn't start as it was deferred due to past failures */
      30                 :            :         COMPACT_DEFERRED,
      31                 :            : 
      32                 :            :         /* compaction not active last round */
      33                 :            :         COMPACT_INACTIVE = COMPACT_DEFERRED,
      34                 :            : 
      35                 :            :         /* For more detailed tracepoint output - internal to compaction */
      36                 :            :         COMPACT_NO_SUITABLE_PAGE,
      37                 :            :         /* compaction should continue to another pageblock */
      38                 :            :         COMPACT_CONTINUE,
      39                 :            : 
      40                 :            :         /*
      41                 :            :          * The full zone was compacted scanned but wasn't successfull to compact
      42                 :            :          * suitable pages.
      43                 :            :          */
      44                 :            :         COMPACT_COMPLETE,
      45                 :            :         /*
      46                 :            :          * direct compaction has scanned part of the zone but wasn't successfull
      47                 :            :          * to compact suitable pages.
      48                 :            :          */
      49                 :            :         COMPACT_PARTIAL_SKIPPED,
      50                 :            : 
      51                 :            :         /* compaction terminated prematurely due to lock contentions */
      52                 :            :         COMPACT_CONTENDED,
      53                 :            : 
      54                 :            :         /*
      55                 :            :          * direct compaction terminated after concluding that the allocation
      56                 :            :          * should now succeed
      57                 :            :          */
      58                 :            :         COMPACT_SUCCESS,
      59                 :            : };
      60                 :            : 
      61                 :            : struct alloc_context; /* in mm/internal.h */
      62                 :            : 
      63                 :            : /*
      64                 :            :  * Number of free order-0 pages that should be available above given watermark
      65                 :            :  * to make sure compaction has reasonable chance of not running out of free
      66                 :            :  * pages that it needs to isolate as migration target during its work.
      67                 :            :  */
      68                 :            : static inline unsigned long compact_gap(unsigned int order)
      69                 :            : {
      70                 :            :         /*
      71                 :            :          * Although all the isolations for migration are temporary, compaction
      72                 :            :          * free scanner may have up to 1 << order pages on its list and then
      73                 :            :          * try to split an (order - 1) free page. At that point, a gap of
      74                 :            :          * 1 << order might not be enough, so it's safer to require twice that
      75                 :            :          * amount. Note that the number of pages on the list is also
      76                 :            :          * effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum
      77                 :            :          * that the migrate scanner can have isolated on migrate list, and free
      78                 :            :          * scanner is only invoked when the number of isolated free pages is
      79                 :            :          * lower than that. But it's not worth to complicate the formula here
      80                 :            :          * as a bigger gap for higher orders than strictly necessary can also
      81                 :            :          * improve chances of compaction success.
      82                 :            :          */
      83                 :          0 :         return 2UL << order;
      84                 :            : }
      85                 :            : 
      86                 :            : #ifdef CONFIG_COMPACTION
      87                 :            : extern int sysctl_compact_memory;
      88                 :            : extern int sysctl_compaction_handler(struct ctl_table *table, int write,
      89                 :            :                         void __user *buffer, size_t *length, loff_t *ppos);
      90                 :            : extern int sysctl_extfrag_threshold;
      91                 :            : extern int sysctl_compact_unevictable_allowed;
      92                 :            : 
      93                 :            : extern int fragmentation_index(struct zone *zone, unsigned int order);
      94                 :            : extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
      95                 :            :                 unsigned int order, unsigned int alloc_flags,
      96                 :            :                 const struct alloc_context *ac, enum compact_priority prio,
      97                 :            :                 struct page **page);
      98                 :            : extern void reset_isolation_suitable(pg_data_t *pgdat);
      99                 :            : extern enum compact_result compaction_suitable(struct zone *zone, int order,
     100                 :            :                 unsigned int alloc_flags, int classzone_idx);
     101                 :            : 
     102                 :            : extern void defer_compaction(struct zone *zone, int order);
     103                 :            : extern bool compaction_deferred(struct zone *zone, int order);
     104                 :            : extern void compaction_defer_reset(struct zone *zone, int order,
     105                 :            :                                 bool alloc_success);
     106                 :            : extern bool compaction_restarting(struct zone *zone, int order);
     107                 :            : 
     108                 :            : /* Compaction has made some progress and retrying makes sense */
     109                 :            : static inline bool compaction_made_progress(enum compact_result result)
     110                 :            : {
     111                 :            :         /*
     112                 :            :          * Even though this might sound confusing this in fact tells us
     113                 :            :          * that the compaction successfully isolated and migrated some
     114                 :            :          * pageblocks.
     115                 :            :          */
     116                 :          0 :         if (result == COMPACT_SUCCESS)
     117                 :            :                 return true;
     118                 :            : 
     119                 :            :         return false;
     120                 :            : }
     121                 :            : 
     122                 :            : /* Compaction has failed and it doesn't make much sense to keep retrying. */
     123                 :            : static inline bool compaction_failed(enum compact_result result)
     124                 :            : {
     125                 :            :         /* All zones were scanned completely and still not result. */
     126                 :          0 :         if (result == COMPACT_COMPLETE)
     127                 :            :                 return true;
     128                 :            : 
     129                 :            :         return false;
     130                 :            : }
     131                 :            : 
     132                 :            : /* Compaction needs reclaim to be performed first, so it can continue. */
     133                 :            : static inline bool compaction_needs_reclaim(enum compact_result result)
     134                 :            : {
     135                 :            :         /*
     136                 :            :          * Compaction backed off due to watermark checks for order-0
     137                 :            :          * so the regular reclaim has to try harder and reclaim something.
     138                 :            :          */
     139                 :          0 :         if (result == COMPACT_SKIPPED)
     140                 :            :                 return true;
     141                 :            : 
     142                 :            :         return false;
     143                 :            : }
     144                 :            : 
     145                 :            : /*
     146                 :            :  * Compaction has backed off for some reason after doing some work or none
     147                 :            :  * at all. It might be throttling or lock contention. Retrying might be still
     148                 :            :  * worthwhile, but with a higher priority if allowed.
     149                 :            :  */
     150                 :            : static inline bool compaction_withdrawn(enum compact_result result)
     151                 :            : {
     152                 :            :         /*
     153                 :            :          * If compaction is deferred for high-order allocations, it is
     154                 :            :          * because sync compaction recently failed. If this is the case
     155                 :            :          * and the caller requested a THP allocation, we do not want
     156                 :            :          * to heavily disrupt the system, so we fail the allocation
     157                 :            :          * instead of entering direct reclaim.
     158                 :            :          */
     159                 :          0 :         if (result == COMPACT_DEFERRED)
     160                 :            :                 return true;
     161                 :            : 
     162                 :            :         /*
     163                 :            :          * If compaction in async mode encounters contention or blocks higher
     164                 :            :          * priority task we back off early rather than cause stalls.
     165                 :            :          */
     166                 :          0 :         if (result == COMPACT_CONTENDED)
     167                 :            :                 return true;
     168                 :            : 
     169                 :            :         /*
     170                 :            :          * Page scanners have met but we haven't scanned full zones so this
     171                 :            :          * is a back off in fact.
     172                 :            :          */
     173                 :          0 :         if (result == COMPACT_PARTIAL_SKIPPED)
     174                 :            :                 return true;
     175                 :            : 
     176                 :            :         return false;
     177                 :            : }
     178                 :            : 
     179                 :            : 
     180                 :            : bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
     181                 :            :                                         int alloc_flags);
     182                 :            : 
     183                 :            : extern int kcompactd_run(int nid);
     184                 :            : extern void kcompactd_stop(int nid);
     185                 :            : extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx);
     186                 :            : 
     187                 :            : #else
     188                 :            : static inline void reset_isolation_suitable(pg_data_t *pgdat)
     189                 :            : {
     190                 :            : }
     191                 :            : 
     192                 :            : static inline enum compact_result compaction_suitable(struct zone *zone, int order,
     193                 :            :                                         int alloc_flags, int classzone_idx)
     194                 :            : {
     195                 :            :         return COMPACT_SKIPPED;
     196                 :            : }
     197                 :            : 
     198                 :            : static inline void defer_compaction(struct zone *zone, int order)
     199                 :            : {
     200                 :            : }
     201                 :            : 
     202                 :            : static inline bool compaction_deferred(struct zone *zone, int order)
     203                 :            : {
     204                 :            :         return true;
     205                 :            : }
     206                 :            : 
     207                 :            : static inline bool compaction_made_progress(enum compact_result result)
     208                 :            : {
     209                 :            :         return false;
     210                 :            : }
     211                 :            : 
     212                 :            : static inline bool compaction_failed(enum compact_result result)
     213                 :            : {
     214                 :            :         return false;
     215                 :            : }
     216                 :            : 
     217                 :            : static inline bool compaction_needs_reclaim(enum compact_result result)
     218                 :            : {
     219                 :            :         return false;
     220                 :            : }
     221                 :            : 
     222                 :            : static inline bool compaction_withdrawn(enum compact_result result)
     223                 :            : {
     224                 :            :         return true;
     225                 :            : }
     226                 :            : 
     227                 :            : static inline int kcompactd_run(int nid)
     228                 :            : {
     229                 :            :         return 0;
     230                 :            : }
     231                 :            : static inline void kcompactd_stop(int nid)
     232                 :            : {
     233                 :            : }
     234                 :            : 
     235                 :            : static inline void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
     236                 :            : {
     237                 :            : }
     238                 :            : 
     239                 :            : #endif /* CONFIG_COMPACTION */
     240                 :            : 
     241                 :            : struct node;
     242                 :            : #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
     243                 :            : extern int compaction_register_node(struct node *node);
     244                 :            : extern void compaction_unregister_node(struct node *node);
     245                 :            : 
     246                 :            : #else
     247                 :            : 
     248                 :            : static inline int compaction_register_node(struct node *node)
     249                 :            : {
     250                 :            :         return 0;
     251                 :            : }
     252                 :            : 
     253                 :            : static inline void compaction_unregister_node(struct node *node)
     254                 :            : {
     255                 :            : }
     256                 :            : #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
     257                 :            : 
     258                 :            : #endif /* _LINUX_COMPACTION_H */