On Thu, May 12, 2022 at 04:46:56PM -0500, Mike Christie wrote: > The following patches were made over Eric's tree: > > git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git > > and his kthread-cleanups-for-v5.19 branch. They allow the vhost layer to > do a copy_process on the thread that does the VHOST_SET_OWNER ioctl like how > io_uring does a copy_process against its userspace app. This allows the > vhost layer's worker threads to inherit cgroups, namespaces, address > space, etc and this worker thread will also be accounted for against that > owner/parent process's RLIMIT_NPROC limit. > > If you are not familiar with qemu and vhost here is more detailed > problem description: > > Qemu will create vhost devices in the kernel which perform network, SCSI, > etc IO and management operations from worker threads created by the > kthread API. Because the kthread API does a copy_process on the kthreadd > thread, the vhost layer has to use kthread_use_mm to access the Qemu > thread's memory and cgroup_attach_task_all to add itself to the Qemu > thread's cgroups. > > The problem with this approach is that we then have to add new functions/ > args/functionality for every thing we want to inherit. I started doing > that here: > > https://lkml.org/lkml/2021/6/23/1233 > > for the RLIMIT_NPROC check, but it seems it might be easier to just > inherit everything from the beginning, becuase I'd need to do something > like that patch several times. Series: Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Who is going to merge this? > V9: > - Rebase against Eric's kthread-cleanups-for-v5.19 branch. Drop patches > no longer needed due to kernel clone arg and pf io worker patches in that > branch. > V8: > - Fix kzalloc GFP use. > - Fix email subject version number. > V7: > - Drop generic user_worker_* helpers and replace with vhost_task specific > ones. > - Drop autoreap patch. Use kernel_wait4 instead. > - Fix issue where vhost.ko could be removed while the worker function is > still running. > V6: > - Rename kernel_worker to user_worker and fix prefixes. > - Add better patch descriptions. > V5: > - Handle kbuild errors by building patchset against current kernel that > has all deps merged. Also add patch to remove create_io_thread code as > it's not used anymore. > - Rebase patchset against current kernel and handle a new vm PF_IO_WORKER > case added in 5.16-rc1. > - Add PF_USER_WORKER flag so we can check it later after the initial > thread creation for the wake up, vm and singal cses. > - Added patch to auto reap the worker thread. > V4: > - Drop NO_SIG patch and replaced with Christian's SIG_IGN patch. > - Merged Christian's kernel_worker_flags_valid helpers into patch 5 that > added the new kernel worker functions. > - Fixed extra "i" issue. > - Added PF_USER_WORKER flag and added check that kernel_worker_start users > had that flag set. Also dropped patches that passed worker flags to > copy_thread and replaced with PF_USER_WORKER check. > V3: > - Add parentheses in p->flag and work_flags check in copy_thread. > - Fix check in arm/arm64 which was doing the reverse of other archs > where it did likely(!flags) instead of unlikely(flags). > V2: > - Rename kernel_copy_process to kernel_worker. > - Instead of exporting functions, make kernel_worker() a proper > function/API that does common work for the caller. > - Instead of adding new fields to kernel_clone_args for each option > make it flag based similar to CLONE_*. > - Drop unused completion struct in vhost. > - Fix compile warnings by merging vhost cgroup cleanup patch and > vhost conversion patch. > > > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
