===================================================================
@@ -791,11 +791,11 @@ static bool too_many_isolated(struct com
unsigned long active, inactive, isolated;
- inactive = node_page_state(pgdat, NR_INACTIVE_FILE) +
+ inactive = node_page_state_snapshot(pgdat, NR_INACTIVE_FILE) +
node_page_state(pgdat, NR_INACTIVE_ANON);
- active = node_page_state(pgdat, NR_ACTIVE_FILE) +
+ active = node_page_state_snapshot(pgdat, NR_ACTIVE_FILE) +
node_page_state(pgdat, NR_ACTIVE_ANON);
- isolated = node_page_state(pgdat, NR_ISOLATED_FILE) +
+ isolated = node_page_state_snapshot(pgdat, NR_ISOLATED_FILE) +
node_page_state(pgdat, NR_ISOLATED_ANON);
/*
===================================================================
@@ -1756,11 +1756,11 @@ static int too_many_isolated(struct pgli
return 0;
if (file) {
- inactive = node_page_state(pgdat, NR_INACTIVE_FILE);
- isolated = node_page_state(pgdat, NR_ISOLATED_FILE);
+ inactive = node_page_state_snapshot(pgdat, NR_INACTIVE_FILE);
+ isolated = node_page_state_snapshot(pgdat, NR_ISOLATED_FILE);
} else {
- inactive = node_page_state(pgdat, NR_INACTIVE_ANON);
- isolated = node_page_state(pgdat, NR_ISOLATED_ANON);
+ inactive = node_page_state_snapshot(pgdat, NR_INACTIVE_ANON);
+ isolated = node_page_state_snapshot(pgdat, NR_ISOLATED_ANON);
}
/*
A customer reported seeing processes hung at too_many_isolated, while analysis indicated that the problem occurred due to out of sync per-CPU stats (see below). Fix is to use node_page_state_snapshot to avoid the out of stale values. 2136 static unsigned long 2137 shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, 2138 struct scan_control *sc, enum lru_list lru) 2139 { : 2145 bool file = is_file_lru(lru); : 2147 struct pglist_data *pgdat = lruvec_pgdat(lruvec); : 2150 while (unlikely(too_many_isolated(pgdat, file, sc))) { 2151 if (stalled) 2152 return 0; 2153 2154 /* wait a bit for the reclaimer. */ 2155 msleep(100); <--- some processes were sleeping here, with pending SIGKILL. 2156 stalled = true; 2157 2158 /* We are about to die and free our memory. Return now. */ 2159 if (fatal_signal_pending(current)) 2160 return SWAP_CLUSTER_MAX; 2161 } msleep() must be called only when there are too many isolated pages: 2019 static int too_many_isolated(struct pglist_data *pgdat, int file, 2020 struct scan_control *sc) 2021 { : 2030 if (file) { 2031 inactive = node_page_state(pgdat, NR_INACTIVE_FILE); 2032 isolated = node_page_state(pgdat, NR_ISOLATED_FILE); 2033 } else { : 2046 return isolated > inactive; The return value was true since: crash> p ((struct pglist_data *) 0xffff00817fffe580)->vm_stat[NR_INACTIVE_FILE] $8 = { counter = 1 } crash> p ((struct pglist_data *) 0xffff00817fffe580)->vm_stat[NR_ISOLATED_FILE] $9 = { counter = 2 while per_cpu stats had: crash> p ((struct pglist_data *) 0xffff00817fffe580)->per_cpu_nodestats $85 = (struct per_cpu_nodestat *) 0xffff8000118832e0 crash> p/x 0xffff8000118832e0 + __per_cpu_offset[42] $86 = 0xffff00917fcc32e0 crash> p ((struct per_cpu_nodestat *) 0xffff00917fcc32e0)->vm_node_stat_diff[NR_ISOLATED_FILE] $87 = -1 '\377' crash> p/x 0xffff8000118832e0 + __per_cpu_offset[44] $89 = 0xffff00917fe032e0 crash> p ((struct per_cpu_nodestat *) 0xffff00917fe032e0)->vm_node_stat_diff[NR_ISOLATED_FILE] $91 = -1 '\377' It seems that processes were trapped in direct reclaim/compaction loop because these nodes had few free pages lower than watermark min. crash> kmem -z | grep -A 3 Normal : NODE: 4 ZONE: 1 ADDR: ffff00817fffec40 NAME: "Normal" SIZE: 8454144 PRESENT: 98304 MIN/LOW/HIGH: 68/166/264 VM_STAT: NR_FREE_PAGES: 68 -- NODE: 5 ZONE: 1 ADDR: ffff00897fffec40 NAME: "Normal" SIZE: 118784 MIN/LOW/HIGH: 82/200/318 VM_STAT: NR_FREE_PAGES: 45 -- NODE: 6 ZONE: 1 ADDR: ffff00917fffec40 NAME: "Normal" SIZE: 118784 MIN/LOW/HIGH: 82/200/318 VM_STAT: NR_FREE_PAGES: 53 -- NODE: 7 ZONE: 1 ADDR: ffff00997fbbec40 NAME: "Normal" SIZE: 118784 MIN/LOW/HIGH: 82/200/318 VM_STAT: NR_FREE_PAGES: 52 Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> --- mm/compaction.c | 6 +++--- mm/vmscan.c | 8 ++++---- 2 files changed, 7 insertions(+), 7 deletions(-)