On Fri, 2019-11-22 at 09:59 -0500, Qian Cai wrote:
> On Thu, 2019-11-21 at 20:37 -0800, Joe Perches wrote:
> > On Thu, 2019-11-21 at 21:55 -0500, Qian Cai wrote:
> > > When running heavy memory pressure workloads, this 5+ old system is
> > > throwing endless warnings below because disk IO is too slow to recover
> > > from swapping. Since the volume from alloc_iova_fast() could be large,
> > > once it calls printk(), it will trigger disk IO (writing to the log
> > > files) and pending softirqs which could cause an infinite loop and make
> > > no progress for days by the ongoimng memory reclaim. This is the counter
> > > part for Intel where the AMD part has already been merged. See the
> > > commit 3d708895325b ("iommu/amd: Silence warnings under memory
> > > pressure"). Since the allocation failure will be reported in
> > > intel_alloc_iova(), so just call printk_ratelimted() there and silence
> > > the one in alloc_iova_mem() to avoid the expensive warn_alloc().
> >
> > []
> > > v2: use dev_err_ratelimited() and improve the commit messages.
> >
> > []
> > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> >
> > []
> > > @@ -3401,7 +3401,8 @@ static unsigned long intel_alloc_iova(struct device
> > > *dev,
> > > iova_pfn = alloc_iova_fast(&domain->iovad, nrpages,
> > > IOVA_PFN(dma_mask), true);
> > > if (unlikely(!iova_pfn)) {
> > > - dev_err(dev, "Allocating %ld-page iova failed", nrpages);
> > > + dev_err_ratelimited(dev, "Allocating %ld-page iova failed",
> > > + nrpages);
> >
> > Trivia:
> >
> > This should really have a \n termination on the format string
> >
> > dev_err_ratelimited(dev, "Allocating %ld-page iova failed\n",
> >
> >
>
> Why do you say so? It is right now printing with a newline added anyway.
>
> hpsa 0000:03:00.0: DMAR: Allocating 1-page iova failed
If another process uses pr_cont at the same time,
it can be interleaved.
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