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    SubjectRe: [PATCH 2/6] oom: Get rid of sparse warnings
    2012/2/6 Anton Vorontsov <anton.vorontsov@linaro.org>:
    > Sparse flood makes it hard to catch newly-introduced warnings. So let's
    > fix the the sparse warnings in the oom killer:
    >
    >  CHECK   mm/oom_kill.c
    >  mm/oom_kill.c:139:20: warning: context imbalance in
    >          '__find_lock_task_mm' - wrong count at exit
    >  mm/oom_kill.c:771:9: warning: context imbalance in 'out_of_memory' -
    >          different lock contexts for basic block
    >
    > The first one is fixed by assuring sparse that we know that we exit
    > with the lock held.
    >
    > The second one is caused by the fact that sparse isn't smart enough
    > to handle noreturn attribute.
    >
    > Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
    > ---
    >  mm/oom_kill.c |    9 ++++++++-
    >  1 files changed, 8 insertions(+), 1 deletions(-)
    >
    > diff --git a/mm/oom_kill.c b/mm/oom_kill.c
    > index 0ebb383..49569b6 100644
    > --- a/mm/oom_kill.c
    > +++ b/mm/oom_kill.c
    > @@ -142,8 +142,14 @@ struct task_struct *__find_lock_task_mm(struct task_struct *p)
    >
    >        do {
    >                task_lock(t);
    > -               if (likely(t->mm))
    > +               if (likely(t->mm)) {
    > +                       /*
    > +                        * Shut up sparse: we do know that we exit w/ the
    > +                        * task locked.
    > +                        */
    > +                       __release(&t->alloc_loc);

    task struct only have allock_lock, not alloc_loc. Moreover we don't release
    the lock in this code path. Seems odd.



    >                        return t;
    > +               }
    >                task_unlock(t);
    >        } while_each_thread(p, t);
    >
    > @@ -766,6 +772,7 @@ retry:
    >                dump_header(NULL, gfp_mask, order, NULL, mpol_mask);
    >                read_unlock(&tasklist_lock);
    >                panic("Out of memory and no killable processes...\n");
    > +               return;
    >        }
    >
    >        if (oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,
    > --
    > 1.7.7.6
    >
    --
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