On Wed, Feb 11, 2015 at 10:58:13AM +0100, Vlastimil Babka wrote:
> On 02/11/2015 08:06 AM, Hugh Dickins wrote:
> >The vmstat interfaces are good at hiding negative counts (at least
> >when CONFIG_SMP); but if you peer behind the curtain, you find that
> >nr_isolated_anon and nr_isolated_file soon go negative, and grow ever
> >more negative: so they can absorb larger and larger numbers of isolated
> >pages, yet still appear to be zero.
> >
> >I'm happy to avoid a congestion_wait() when too_many_isolated() myself;
> >but I guess it's there for a good reason, in which case we ought to get
> >too_many_isolated() working again.
> >
> >The imbalance comes from isolate_migratepages()'s ISOLATE_ABORT case:
> >putback_movable_pages() decrements the NR_ISOLATED counts, but we forgot
> >to call acct_isolated() to increment them.
> >
> >Fixes: edc2ca612496 ("mm, compaction: move pageblock checks up from isolate_migratepages_range()")
>
> Ccing Joonsoo for completeness, as it seems he contributed to this
> part [1] (to fix another bug of mine, not trying to dismiss
> responsibility)
>
> But yeah it looks correct. Thanks for finding and fixing!
Yes, it looks correct to me.
Acked-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
>
> [1] https://lkml.org/lkml/2014/9/29/60
>
> >Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
> >Cc: stable@xxxxxxxxxxxxxxx # v3.18+
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