Messages in this thread | | | Date | Mon, 12 Feb 2024 21:10:38 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 2/2] x86/MCE: Add command line option to extend MCE Records pool |
| |
On Mon, Feb 12, 2024 at 07:49:43PM +0000, Luck, Tony wrote: > Yes. The question is whether a #MC that come in the middle of list_rcu_add() > can safely do list_for_each_entry_rcu() on the same list. > > RCU is black magic ... maybe it can do this? Adding Paul.
Yeah, the list traversal might be ok as this is what that list_add does - you can't encounter an inconsistent list - but we still take a spinlock on addition and the commit which added it:
7f184275aa30 ("lib, Make gen_pool memory allocator lockless")
says
The lockless operation only works if there is enough memory available. If new memory is added to the pool a lock has to be still taken. So any user relying on locklessness has to ensure that sufficient memory is preallocated.
and this is exactly what we're doing - adding new memory.
So, until we're absolutely sure that it is ok to interrupt a context holding a spinlock with a #MC which is non-maskable, I don't think we wanna do this.
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
| |