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 the > > Have 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 ?
No, that's wrong. ->count_objects should never ass SHRINK_STOP. Indeed, it should always return a count of objects in the cache, regardless of the context. SHRINK_STOP is for ->scan_objects to tell the shrinker it can make any progress due to the context it is called in. This allows the shirnker to defer the work to another call in a different context. However, if ->count-objects doesn't return a count, the work that was supposed to be done cannot be deferred, and that is what ->count_objects should always return the number of objects in the cache. Cheers, Dave. -- Dave Chinner da...@fromorbit.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
