On Fri, Sep 18, 2020 at 02:45:25PM +0200, Christoph Hellwig wrote: > Add a flag to force processing a syscall as a compat syscall. This is > required so that in_compat_syscall() works for I/O submitted by io_uring > helper threads on behalf of compat syscalls. Al doesn't like this much, but my suggestion is to introduce two new opcodes -- IORING_OP_READV32 and IORING_OP_WRITEV32. The compat code can translate IORING_OP_READV to IORING_OP_READV32 and then the core code can know what that user pointer is pointing to.