On 1/17/19 1:03 PM, Jeff Moyer wrote: > Jens Axboe <[email protected]> writes: > >> On 1/17/19 5:48 AM, Roman Penyaev wrote: >>> On 2019-01-16 18:49, Jens Axboe wrote: >>> >>> [...] >>> >>>> +static int io_allocate_scq_urings(struct io_ring_ctx *ctx, >>>> + struct io_uring_params *p) >>>> +{ >>>> + struct io_sq_ring *sq_ring; >>>> + struct io_cq_ring *cq_ring; >>>> + size_t size; >>>> + int ret; >>>> + >>>> + sq_ring = io_mem_alloc(struct_size(sq_ring, array, p->sq_entries)); >>> >>> It seems that sq_entries, cq_entries are not limited at all. Can nasty >>> app consume a lot of kernel pages calling io_setup_uring() from a loop >>> passing random entries number? (or even better: decreasing entries >>> number, >>> in order to consume all pages orders with min number of loops). >> >> Yes, that's an oversight, we should have a limit in place. I'll add that. > > Can we charge the ring memory to the RLIMIT_MEMLOCK as well? I'd prefer > not to repeat the mistake of fs.aio-max-nr.
Sure, we can do that. With the ring limited in size (it's now 4k entries at most), the amount of memory gobbled up by that is much smaller than the fixed buffers. A max sized ring is about 256k of memory. -- Jens Axboe
