From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 05/15] Add io_uring IO interface Date: Thu, 17 Jan 2019 13:09:06 -0700 Message-ID: References: <20190116175003.17880-1-axboe@kernel.dk> <20190116175003.17880-6-axboe@kernel.dk> <718b4d1fbe9f97592d6d7b76d7a4537d@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: owner-linux-aio@kvack.org To: Jeff Moyer Cc: Roman Penyaev , linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org, hch@lst.de, avi@scylladb.com, linux-block-owner@vger.kernel.org List-Id: linux-arch.vger.kernel.org On 1/17/19 1:03 PM, Jeff Moyer wrote: > Jens Axboe 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 -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: aart@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-f66.google.com ([209.85.166.66]:39553 "EHLO mail-io1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729327AbfAQUJJ (ORCPT ); Thu, 17 Jan 2019 15:09:09 -0500 Received: by mail-io1-f66.google.com with SMTP id k7so8871029iob.6 for ; Thu, 17 Jan 2019 12:09:09 -0800 (PST) Subject: Re: [PATCH 05/15] Add io_uring IO interface References: <20190116175003.17880-1-axboe@kernel.dk> <20190116175003.17880-6-axboe@kernel.dk> <718b4d1fbe9f97592d6d7b76d7a4537d@suse.de> From: Jens Axboe Message-ID: Date: Thu, 17 Jan 2019 13:09:06 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Jeff Moyer Cc: Roman Penyaev , linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org, hch@lst.de, avi@scylladb.com, linux-block-owner@vger.kernel.org Message-ID: <20190117200906.YU_NiAlEVAZ8j_NLZiTcRhv46b68rJ3TiPVVwMSFX7g@z> On 1/17/19 1:03 PM, Jeff Moyer wrote: > Jens Axboe 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