On 02/01/2026 22:44, David Laight wrote: > On Fri, 2 Jan 2026 13:11:52 +0000 > Ryan Roberts <[email protected]> wrote: > >> kstack_offset was previously maintained per-cpu, but this caused a >> couple of issues. So let's instead make it per-task. >> >> Issue 1: add_random_kstack_offset() and choose_random_kstack_offset() >> expected and required to be called with interrupts and preemption >> disabled so that it could manipulate per-cpu state. But arm64, loongarch >> and risc-v are calling them with interrupts and preemption enabled. I >> don't _think_ this causes any functional issues, but it's certainly >> unexpected and could lead to manipulating the wrong cpu's state, which >> could cause a minor performance degradation due to bouncing the cache >> lines. By maintaining the state per-task those functions can safely be >> called in preemptible context. >> >> Issue 2: add_random_kstack_offset() is called before executing the >> syscall and expands the stack using a previously chosen rnadom offset. > <> > David
Cheers; will fix in next version. Thanks, Ryan
