>>> Am Freitag, den 02.12.2016, 11:18 +0100 schrieb Vlastimil Babka: >>>> I don't think we should just hide the issue like this, as getting high >>>> volume reports from this is also very likely associated with high >>>> overhead for the allocations. If it's the generic dma-cma context, like >>>> in [1] where it attempts CMA for order-0 allocations, we should first do >>>> something about that, before tweaking the logging. That was also my concern. Ideally we would have a counter which increments whenever isolation failure happens and some monitoring of that counter but this is kernel so that’s just a pipe dream. >> On Fri 02-12-16 11:41:11, Lucas Stach wrote: >>> Still this message is really disturbing as page isolation failures can >>> be caused by lots of other reasons like temporarily pinned pages. Just so we’re on the same page, lots of allocations is not a *reason* of isolation failures. It only surfaces it. This is not to disagree about better having code that is smart about allocating DMA buffers. This is true regardless. > Am Freitag, den 02.12.2016, 11:48 +0100 schrieb Michal Hocko: >> Hmm, then I think that what Robin has proposed [1] should be a generally >> better solution because it both ratelimits and points to the user who is >> triggering this path. On Fri, Dec 02 2016, Lucas Stach wrote: > Dumping a stacktrace at this point is only going to increase the noise > from this message, as it can be trigger under normal operating > conditions of CMA. If someone temporarily locked a previously movable > page with GUP or something alike, the stacktrace will point to the > victim rather than the offender, so I think the value of the stackstrace > is rather limited. I agree, which is why I suggested printing the stack only if CONFIG_CMA_DEBUG is enabled. -- Best regards ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ «If at first you don’t succeed, give up skydiving» -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href