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| author | Konstantin Khlebnikov <khlebnikov@openvz.org> | 2011-12-08 14:33:51 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-12-09 07:50:27 -0800 |
| commit | 635697c663f38106063d5659f0cf2e45afcd4bb5 (patch) | |
| tree | 3aba50aabc16eeb63d5e21979a3fdf163ccabda2 | |
| parent | 09d9673d53005fdf40de4c759425893904292236 (diff) | |
| download | blackbird-op-linux-635697c663f38106063d5659f0cf2e45afcd4bb5.tar.gz blackbird-op-linux-635697c663f38106063d5659f0cf2e45afcd4bb5.zip | |
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.c | 9 |
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); |
