[Devel] [PATCH vz10 2/2] ve/net/neighbour: base forced-GC reclaim target on the per-VE counter

[Konstantin Khorenko]

neigh_forced_gc() already counts only same-VE reclaims into "shrunk" and
is reached from neigh_alloc() when a container hits its per-VE gc_thresh3
limit, but its reclaim target was still derived from the global counter:

	max_clean = atomic_read(&tbl->gc_entries) - gc_thresh2;

With several containers tbl->gc_entries is the sum across all of them, so
max_clean balloons far beyond the number of entries the allocating
container actually owns. The "shrunk >= max_clean" stop condition is then
never reached and forced GC walks the entire global gc_list on every call
(until the 16-iteration / 1 ms budget runs out), churning other VEs'
entries instead of stopping once the offending VE is back under its limit.

Derive max_clean from the per-VE counter so the trigger, the reclaim
target and the counted reclaims are all per-VE; fall back to the global
counter when there is no per-VE counter for the table family.

Fixes: 5f0a2a6f78f7 ("ve/net/neighbour: per-ct limit for neighbour entries")
https://virtuozzo.atlassian.net/browse/VSTOR-132310
Feature: net: make the neighbor entries limit per-CT
Reported-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 net/core/neighbour.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index cf1f11a596d8..f90deb17fb25 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -275,7 +275,9 @@ bool neigh_remove_one(struct neighbour *ndel, struct neigh_table *tbl)
 
 static int neigh_forced_gc(struct neigh_table *tbl, struct ve_struct *ve)
 {
-	int max_clean = atomic_read(&tbl->gc_entries) -
+	atomic_t *cnt = get_perve_tbl_entries_counter(tbl, ve);
+	int max_clean = (cnt ? atomic_read(cnt) :
+			       atomic_read(&tbl->gc_entries)) -
 			READ_ONCE(tbl->gc_thresh2);
 	u64 tmax = ktime_get_ns() + NSEC_PER_MSEC;
 	unsigned long tref = jiffies - 5 * HZ;
-- 
2.47.1