On Fri, Feb 13, 2026 at 01:26:32AM +0000, Shinichiro Kawasaki wrote: > Cc+: Thomas, > > On Jan 30, 2026 / 20:16, Shin'ichiro Kawasaki wrote: > > On Jan 29, 2026 / 15:19, Paul E. McKenney wrote: > > [...] > > > And Thomas Gleixner posted an alleged fix to the CID issue here: > > > > > > https://lore.kernel.org/lkml/[email protected]/ > > > > > > Please let him know whether or not it helps. > > > > Good to see this fix candidate series, thanks :) I have set up the patches > > and > > started my regular test runs. So far, the hangs have been observed once or > > twice > > a week. To confirm the effect of the fix series, I think two weeks runs > > will be > > required. Once I get the result, will share it on this thread and with > > Thomas. > > Two weeks have passed, and I did not observed the hang! Then I'm confident > that > the v1 fix series by Thomas avoided the rcu stall issue in my xfs-zoned test > systems. The series is already in v6.19 kernel tag as v2. Great. > > Thomas, just FYI. > > I faced mysterious kernel hangs during my regular fstests runs [1]. RCU > experts > suggested the hangs might be caused by the recent MMCID changes. I tried your > v1 > fix patch series "sched/mmcid: Cure mode transition woes", and confirmed it > avoids the hangs. Thank you for the fix. The v2 series is already in v6.19 > kernel tag, so this report might not be so valuable, but just in case. (And > thank you again for the additional quick fix for my blktests failure caused by > one of the patches in the series). > > [1] https://lore.kernel.org/rcu/aXdO52wh2rqTUi1E@shinmob/
Good to see that this got resolved. I am guessing there's nothing from an RCU point of view that could be done differently to diagnose this earlier, since I pretty quickly spotted it was MMCID related when I saw the existing report. Let me/us RCU folk know if there's anything else to do here though.. thanks, -- Joel Fernandes
