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authorKonstantin Khlebnikov <khlebnikov@openvz.org>2011-12-08 14:33:51 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-12-09 07:50:27 -0800
commit635697c663f38106063d5659f0cf2e45afcd4bb5 (patch)
tree3aba50aabc16eeb63d5e21979a3fdf163ccabda2
parent09d9673d53005fdf40de4c759425893904292236 (diff)
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 <khlebnikov@openvz.org> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/vmscan.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a1893c050795..f5255442ae2b 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);