From 635697c663f38106063d5659f0cf2e45afcd4bb5 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 8 Dec 2011 14:33:51 -0800 Subject: [PATCH] vmscan: fix initial shrinker size handling A shrinker function can return -1, means that it cannot do anything without a risk of deadlock. For example prune_super() does this if it cannot grab a superblock refrence, even if nr_to_scan=0. Currently we interpret this -1 as a ULONG_MAX size shrinker and evaluate `total_scan' according to this. So the next time around this shrinker can cause really big pressure. Let's skip such shrinkers instead. Also make total_scan signed, otherwise the check (total_scan < 0) below never works. Signed-off-by: Konstantin Khlebnikov Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index a1893c05079..f5255442ae2 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -247,14 +247,18 @@ unsigned long shrink_slab(struct shrink_control *shrink, list_for_each_entry(shrinker, &shrinker_list, list) { unsigned long long delta; - unsigned long total_scan; - unsigned long max_pass; + long total_scan; + long max_pass; int shrink_ret = 0; long nr; long new_nr; long batch_size = shrinker->batch ? shrinker->batch : SHRINK_BATCH; + max_pass = do_shrinker_shrink(shrinker, shrink, 0); + if (max_pass <= 0) + continue; + /* * copy the current shrinker scan count into a local variable * and zero it so that other concurrent shrinker invocations @@ -265,7 +269,6 @@ unsigned long shrink_slab(struct shrink_control *shrink, } while (cmpxchg(&shrinker->nr, nr, 0) != nr); total_scan = nr; - max_pass = do_shrinker_shrink(shrinker, shrink, 0); delta = (4 * nr_pages_scanned) / shrinker->seeks; delta *= max_pass; do_div(delta, lru_pages + 1);