On Tue, Jan 14, 2025 at 6:51 PM Valentin Schneider <vschneid@xxxxxxxxxx> wrote: > vunmap()'s issued from housekeeping CPUs are a relatively common source of > interference for isolated NOHZ_FULL CPUs, as they are hit by the > flush_tlb_kernel_range() IPIs. > > Given that CPUs executing in userspace do not access data in the vmalloc > range, these IPIs could be deferred until their next kernel entry. > > Deferral vs early entry danger zone > =================================== > > This requires a guarantee that nothing in the vmalloc range can be vunmap'd > and then accessed in early entry code. In other words, it needs a guarantee that no vmalloc allocations that have been created in the vmalloc region while the CPU was idle can then be accessed during early entry, right?
