Re: [patch V4 part 5 07/31] x86/entry: Provide idtentry_entry/exit_cond_rcu()

2020-05-12 Thread Thomas Gleixner
Alexandre Chartre writes: > On 5/5/20 3:53 PM, Thomas Gleixner wrote: >> The pagefault handler cannot use the regular idtentry_enter() because on >> that invokes rcu_irq_enter() the pagefault was caused in the kernel. > > I am struggling to understand this part of the sentence: "because on > that

Re: [patch V4 part 5 07/31] x86/entry: Provide idtentry_entry/exit_cond_rcu()

2020-05-11 Thread Peter Zijlstra
On Mon, May 11, 2020 at 03:53:17PM +0200, Alexandre Chartre wrote: > > On 5/5/20 3:53 PM, Thomas Gleixner wrote: > > The pagefault handler cannot use the regular idtentry_enter() because on > > that invokes rcu_irq_enter() the pagefault was caused in the kernel. > > I am struggling to understand

Re: [patch V4 part 5 07/31] x86/entry: Provide idtentry_entry/exit_cond_rcu()

2020-05-11 Thread Alexandre Chartre
On 5/5/20 3:53 PM, Thomas Gleixner wrote: The pagefault handler cannot use the regular idtentry_enter() because on that invokes rcu_irq_enter() the pagefault was caused in the kernel. I am struggling to understand this part of the sentence: "because on that invokes rcu_irq_enter() the

[patch V4 part 5 07/31] x86/entry: Provide idtentry_entry/exit_cond_rcu()

2020-05-05 Thread Thomas Gleixner
The pagefault handler cannot use the regular idtentry_enter() because on that invokes rcu_irq_enter() the pagefault was caused in the kernel. Not a problem per se, but kernel side page faults can schedule which is not possible without invoking rcu_irq_exit(). Adding rcu_irq_exit() and a matching