Re: mpol_to_str revisited.

From: Dave Jones
Date: Mon Oct 08 2012 - 16:52:12 EST


On Mon, Oct 08, 2012 at 01:35:42PM -0700, David Rientjes wrote:

> > unanswered question: why are the buffer sizes here different ? which is correct?
> >
> Given the current set of mempolicy modes and flags, it's 34, but this can
> change if new modes or flags are added with longer names. I see no reason
> why shmem shouldn't round up to the nearest power-of-2 of 64 like it
> already does, but 50 is certainly safe as well in task_mmu.c.

Ok. I'll leave that for now.

> > diff -durpN '--exclude-from=/home/davej/.exclude' src/git-trees/kernel/linux/fs/proc/task_mmu.c linux-dj/fs/proc/task_mmu.c
> > --- src/git-trees/kernel/linux/fs/proc/task_mmu.c 2012-05-31 22:32:46.778150675 -0400
> > +++ linux-dj/fs/proc/task_mmu.c 2012-10-04 19:31:41.269988984 -0400
> > @@ -1162,6 +1162,7 @@ static int show_numa_map(struct seq_file
> > struct mm_walk walk = {};
> > struct mempolicy *pol;
> > int n;
> > + int ret;
> > char buffer[50];
> >
> > if (!mm)
> > @@ -1178,7 +1179,11 @@ static int show_numa_map(struct seq_file
> > walk.mm = mm;
> >
> > pol = get_vma_policy(proc_priv->task, vma, vma->vm_start);
> > - mpol_to_str(buffer, sizeof(buffer), pol, 0);
> > + memset(buffer, 0, sizeof(buffer));
> > + ret = mpol_to_str(buffer, sizeof(buffer), pol, 0);
> > + if (ret < 0)
> > + return 0;
>
> We should need the mpol_cond_put(pol) here before returning.

good catch. I'll respin the patch later with this changed.

thanks,

Dave


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