On Mon, Nov 08, 2021 at 12:56:21PM -0800, Reinette Chatre wrote: > Hi Jarkko, > > On 11/8/2021 12:12 PM, Jarkko Sakkinen wrote: > > On Mon, Nov 08, 2021 at 11:48:18AM -0800, Reinette Chatre wrote: > > > Hi Jarkko, > > > > > > On 11/7/2021 8:47 AM, Jarkko Sakkinen wrote: > > > > On Sun, 2021-11-07 at 18:45 +0200, Jarkko Sakkinen wrote: > > > > > On Thu, 2021-11-04 at 11:28 -0700, Reinette Chatre wrote: > > > > > > The consequence of sgx_nr_free_pages not being protected is that > > > > > > its value may not accurately reflect the actual number of free > > > > > > pages on the system, impacting the availability of free pages in > > > > > > support of many flows. The problematic scenario is when the > > > > > > reclaimer never runs because it believes there to be sufficient > > > > > > free pages while any attempt to allocate a page fails because there > > > > > > are no free pages available. The worst scenario observed was a > > > > > > user space hang because of repeated page faults caused by > > > > > > no free pages ever made available. > > > > > > > > > > Can you go in detail with the "concrete scenario" in the commit > > > > > message? It does not have to describe all the possible scenarios > > > > > but at least one sequence of events. > > > > > > > > > I provided significant detail regarding the "concrete scenario" in a > > > separate response to Greg: > > > https://lore.kernel.org/lkml/a636290d-db04-be16-1c86-a8dcc3719b39@xxxxxxxxx/ > > > > > > That message details the test that was run (the test hangs before the fix > > > and can complete after the fix), the traces captured at the time the test > > > hung, analysis of the traces with root cause of why the system is hung, > > > traces after fix applied demonstrating why user space is able to make > > > progress and explaining why the test can complete. > > > > For me that sequence looks like something that you could "abstract" > > a bit and get a rough description of the concurrency scenario. > > > > It is as important in this type of patch, as the code change itself, > > not least because it helps with maintaining in the future to have > > that info in some level of detail in the commit log. > > My apologies. I understood your comment to be a concern with the change > itself instead of just the commit message. I will add more detail about the > failing scenario encountered to the commit message. Yeah, I went through the log and the code change makes sense :-) /Jarkko
