From: Rob Clark <robdclark@chromium.org>

Ratelimit the error msg to avoid flooding the console.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 kernel/dma/debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index f8ff598596b8..683966f0247b 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -564,7 +564,7 @@ static void add_dma_entry(struct dma_debug_entry *entry, unsigned long attrs)
 
 	rc = active_cacheline_insert(entry);
 	if (rc == -ENOMEM) {
-		pr_err("cacheline tracking ENOMEM, dma-debug disabled\n");
+		pr_err_ratelimited("cacheline tracking ENOMEM, dma-debug disabled\n");
 		global_disable = true;
 	} else if (rc == -EEXIST && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
 		err_printk(entry->dev, entry,
-- 
2.36.1

On 2022-05-31 22:51, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> Ratelimit the error msg to avoid flooding the console.
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>   kernel/dma/debug.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
> index f8ff598596b8..683966f0247b 100644
> --- a/kernel/dma/debug.c
> +++ b/kernel/dma/debug.c
> @@ -564,7 +564,7 @@ static void add_dma_entry(struct dma_debug_entry *entry, unsigned long attrs)
>   
>   	rc = active_cacheline_insert(entry);
>   	if (rc == -ENOMEM) {
> -		pr_err("cacheline tracking ENOMEM, dma-debug disabled\n");
> +		pr_err_ratelimited("cacheline tracking ENOMEM, dma-debug disabled\n");
>   		global_disable = true;

Given that it's supposed to disable itself entirely if it ever gets 
here, just how spammy is it exactly?

Thanks,
Robin.

>   	} else if (rc == -EEXIST && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
>   		err_printk(entry->dev, entry,

On Tue, May 31, 2022 at 3:00 PM Robin Murphy <robin.murphy@arm.com> wrote:
>
> On 2022-05-31 22:51, Rob Clark wrote:
> > From: Rob Clark <robdclark@chromium.org>
> >
> > Ratelimit the error msg to avoid flooding the console.
> >
> > Signed-off-by: Rob Clark <robdclark@chromium.org>
> > ---
> >   kernel/dma/debug.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
> > index f8ff598596b8..683966f0247b 100644
> > --- a/kernel/dma/debug.c
> > +++ b/kernel/dma/debug.c
> > @@ -564,7 +564,7 @@ static void add_dma_entry(struct dma_debug_entry *entry, unsigned long attrs)
> >
> >       rc = active_cacheline_insert(entry);
> >       if (rc == -ENOMEM) {
> > -             pr_err("cacheline tracking ENOMEM, dma-debug disabled\n");
> > +             pr_err_ratelimited("cacheline tracking ENOMEM, dma-debug disabled\n");
> >               global_disable = true;
>
> Given that it's supposed to disable itself entirely if it ever gets
> here, just how spammy is it exactly?

um, quite..  tbf that was in the context of a WIP igt test for
shrinker which was trying to cycle thru ~2x RAM size worth of GEM
buffers on something like 72 threads.  So it could just be threads
that had gotten past the dma_debug_disabled() check already before
global_disable was set to true?

I guess this could be pr_err_once() instead, then?

BR,
-R

> Thanks,
> Robin.
>
> >       } else if (rc == -EEXIST && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
> >               err_printk(entry->dev, entry,

On Tue, May 31, 2022 at 03:19:45PM -0700, Rob Clark wrote:
> um, quite..  tbf that was in the context of a WIP igt test for
> shrinker which was trying to cycle thru ~2x RAM size worth of GEM
> buffers on something like 72 threads.  So it could just be threads
> that had gotten past the dma_debug_disabled() check already before
> global_disable was set to true?
> 
> I guess this could be pr_err_once() instead, then?

Yes, we could use pr_err_once to reduce the chattyness while still
keeping global_disable to disable all the actual tracking.