| Date | Thu, 5 Nov 2020 12:44:08 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH 4.19 057/191] sparc64: remove mm_cpumask clearing to fix kthread_use_mm race |
| |
Hi!
> From: Nicholas Piggin <npiggin@gmail.com> > > [ Upstream commit bafb056ce27940c9994ea905336aa8f27b4f7275 ] ... > io_uring 2b188cc1bb857 ("Add io_uring IO interface") added code which > does a kthread_use_mm() from a mmget_not_zero() refcount. ... > The basic fix for sparc64 is to remove its mm_cpumask clearing code. The > optimisation could be effectively restored by sending IPIs to mm_cpumask > members and having them remove themselves from mm_cpumask. This is more > tricky so I leave it as an exercise for someone with a sparc64 SMP. > powerpc has a (currently similarly broken) example.
So this removes optimalization from Sparc, because it clashes with 2b188cc1bb857 ("Add io_uring IO interface"). But that commit is not present in 4.19... so this probably is not good idea.
Best regards, Pavel -- http://www.livejournal.com/~pavelmachek [unhandled content-type:application/pgp-signature] |