On Mon, Jun 06, 2022 at 02:00:33PM -0700, John Johansen wrote: > On 6/6/22 13:23, Matthew Wilcox wrote: > > On Mon, Jun 06, 2022 at 12:19:36PM -0700, John Johansen wrote: > >>> I suspect that part is that both Apparmor and IPC use the idr local lock. > >>> > >> bingo, > >> > >> apparmor moved its secids allocation from a custom radix tree to idr in > >> > >> 99cc45e48678 apparmor: Use an IDR to allocate apparmor secids > >> > >> and ipc is using the idr for its id allocation as well > >> > >> I can easily lift the secid() allocation out of the ctx->lock but that > >> would still leave it happening under the file_lock and not fix the problem. > >> I think the quick solution would be for apparmor to stop using idr, reverting > >> back at least temporarily to the custom radix tree. > > > > How about moving forward to the XArray that doesn't use that horrid > > prealloc gunk? Compile tested only. > > > > I'm not very familiar with XArray but it does seem like a good fit. We do try > to keep the secid allocation dense, ideally no holes. Wrt the current locking > issue I want to hear what Thomas has to say. Regardless I am looking into > whether we should just switch to XArrays going forward. Nothing from Thomas ... shall we just go with this? Do you want a commit message, etc for the patch?
