From: Konstantin Khlebnikov <khlebnikov@openvz.org>
Date: Thu, 8 Dec 2011 22:33:51 +0000 (-0800)
Subject: vmscan: fix initial shrinker size handling
X-Git-Tag: v3.2-rc5~26
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=635697c663f38106063d5659f0cf2e45afcd4bb5;p=pandora-kernel.git

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>
---

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