On Wed, Sep 18, 2013 at 12:38:23PM +0200, Knut Petersen wrote:
On 18.09.2013 11:10, Daniel Vetter wrote:
Just now I prepared a patch changing the same function in vmscan.c
Also, this needs to be rebased to the new shrinker api in 3.12, I simply haven't rolled my trees forward yet.
Well, you should. Since commit 81e49f shrinker->count_objects might be set to SHRINK_STOP, causing shrink_slab_node() to complain loud and often:
[ 1908.234595] shrink_slab: i915_gem_inactive_scan+0x0/0x9c negative objects to delete nr=-xxxxxxxxx
The kernel emitted a few thousand log lines like the one quoted above during the last few days on my system.
diff --git a/mm/vmscan.c b/mm/vmscan.c index 2cff0d4..d81f6e0 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -254,6 +254,10 @@ unsigned long shrink_slab(struct shrink_control *shrink, total_scan = max_pass; }
/* Always try to shrink a bit to make forward progress. */if (shrinker->evicts_to_page_lru)total_scan = max_t(long, total_scan, batch_size);At that place the error message is already emitted.
/* * We need to avoid excessive windup on filesystem shrinkers * due to large numbers of GFP_NOFS allocations causing theHave a look at the attached patch. It fixes my problem with the erroneous/misleading error messages, and I think it´s right to just bail out early if SHRINK_STOP is found.
Do you agree ?
Looking at the patch which introduced these error message for you, which changed the ->count_objects return value from 0 to SHRINK_STOP your patch below to treat 0 and SHRINK_STOP equally simply reverts the functional change.
I don't think that's the intention behind SHRINK_STOP. But if it's the right think to do we better revert the offending commit directly. And since I lack clue I think that's a call for core mm guys to make. -Daniel
cu, Knut
From 75ae570ce7b0bb6b40c76beb18fc075e9af3127a Mon Sep 17 00:00:00 2001 From: Knut Petersen Knut_Petersen@t-online.de Date: Wed, 18 Sep 2013 12:06:33 +0200 Subject: [PATCH] mm: respect SHRINK_STOP in shrink_slab_node()
Since commit 81e49f811404f428a9d9a63295a0c267e802fa12 i915_gem_inactive_count() might return SHRINK_STOP.
Unfortunately SHRINK_STOP is not handled propperly in shrink_slab_node(), causing a system log cluttered with kernel error messages complaining about "negative objects to delete".
I think the proper way of handling SHRINK_STOP is obvious, we should obey ;-)
Signed-off-by: Knut Petersen Knut_Petersen@t-online.de
mm/vmscan.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/mm/vmscan.c b/mm/vmscan.c index 8ed1b77..b1e6f0d 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -244,6 +244,8 @@ shrink_slab_node(struct shrink_control *shrinkctl, struct shrinker *shrinker, max_pass = shrinker->count_objects(shrinker, shrinkctl); if (max_pass == 0) return 0;
if (max_pass == SHRINK_STOP)
return 0;/*
- copy the current shrinker scan count into a local variable
-- 1.8.1.4