The patch titled
vmscan: fix initial shrinker size handling
has been added to the -mm tree. Its filename is
vmscan-fix-initial-shrinker-size-handling.patch
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------------------------------------------------------
Subject: vmscan: fix initial shrinker size handling
From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff -puN mm/vmscan.c~vmscan-fix-initial-shrinker-size-handling mm/vmscan.c
--- a/mm/vmscan.c~vmscan-fix-initial-shrinker-size-handling
+++ a/mm/vmscan.c
@@ -248,14 +248,18 @@ unsigned long shrink_slab(struct 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
@@ -266,7 +270,6 @@ unsigned long shrink_slab(struct 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);
_
Patches currently in -mm which might be from khlebnikov@xxxxxxxxxx are
vmscan-fix-initial-shrinker-size-handling.patch
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