@@ -85,6 +85,47 @@ struct khugepaged_scan {
8585.mm_head = LIST_HEAD_INIT (khugepaged_scan .mm_head ),
8686};
8787
88+
89+ static int set_recommended_min_free_kbytes (void )
90+ {
91+ struct zone * zone ;
92+ int nr_zones = 0 ;
93+ unsigned long recommended_min ;
94+ extern int min_free_kbytes ;
95+
96+ if (!test_bit (TRANSPARENT_HUGEPAGE_FLAG ,
97+ & transparent_hugepage_flags )&&
98+ !test_bit (TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG ,
99+ & transparent_hugepage_flags ))
100+ return 0 ;
101+
102+ for_each_populated_zone (zone )
103+ nr_zones ++ ;
104+
105+ /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
106+ recommended_min = pageblock_nr_pages * nr_zones * 2 ;
107+
108+ /*
109+ * Make sure that on average at least two pageblocks are almost free
110+ * of another type, one for a migratetype to fall back to and a
111+ * second to avoid subsequent fallbacks of other types There are 3
112+ * MIGRATE_TYPES we care about.
113+ */
114+ recommended_min += pageblock_nr_pages * nr_zones *
115+ MIGRATE_PCPTYPES * MIGRATE_PCPTYPES ;
116+
117+ /* don't ever allow to reserve more than 5% of the lowmem */
118+ recommended_min = min (recommended_min ,
119+ (unsigned long )nr_free_buffer_pages () /20 );
120+ recommended_min <<= (PAGE_SHIFT - 10 );
121+
122+ if (recommended_min > min_free_kbytes )
123+ min_free_kbytes = recommended_min ;
124+ setup_per_zone_wmarks ();
125+ return 0 ;
126+ }
127+ late_initcall (set_recommended_min_free_kbytes );
128+
88129static int start_khugepaged (void )
89130{
90131int err = 0 ;
@@ -108,6 +149,8 @@ static int start_khugepaged(void)
108149mutex_unlock (& khugepaged_mutex );
109150if (wakeup )
110151wake_up_interruptible (& khugepaged_wait );
152+
153+ set_recommended_min_free_kbytes ();
111154}else
112155/* wakeup to exit */
113156wake_up_interruptible (& khugepaged_wait );
@@ -177,6 +220,13 @@ static ssize_t enabled_store(struct kobject *kobj,
177220ret = err ;
178221}
179222
223+ if (ret > 0 &&
224+ (test_bit (TRANSPARENT_HUGEPAGE_FLAG ,
225+ & transparent_hugepage_flags )||
226+ test_bit (TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG ,
227+ & transparent_hugepage_flags )))
228+ set_recommended_min_free_kbytes ();
229+
180230return ret ;
181231}
182232static struct kobj_attribute enabled_attr =
@@ -464,6 +514,8 @@ static int __init hugepage_init(void)
464514
465515start_khugepaged ();
466516
517+ set_recommended_min_free_kbytes ();
518+
467519out :
468520return err ;
469521}