From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Penyaev Subject: Re: [PATCH 05/15] Add io_uring IO interface Date: Thu, 17 Jan 2019 13:02:21 +0100 Message-ID: <362738449bd3f83d18cb1056acc9b875@suse.de> References: <20190116175003.17880-1-axboe@kernel.dk> <20190116175003.17880-6-axboe@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190116175003.17880-6-axboe@kernel.dk> Sender: owner-linux-aio@kvack.org To: Jens Axboe Cc: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org, hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, linux-block-owner@vger.kernel.org List-Id: linux-arch.vger.kernel.org Hi Jens, On 2019-01-16 18:49, Jens Axboe wrote: [...] > +static void *io_mem_alloc(size_t size) > +{ > + gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP > | > + __GFP_NORETRY; > + > + return (void *) __get_free_pages(gfp_flags, get_order(size)); Since these pages are shared between kernel and userspace, do we need to care about d-cache aliasing on armv6 (or other "strange" archs which I've never seen) with vivt or vipt cpu caches? E.g. vmalloc_user() targets this problem by aligning kernel address on SHMLBA, so no flush_dcache_page() is required. -- Roman -- 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 mx2.suse.de ([195.135.220.15]:55592 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726964AbfAQMCX (ORCPT ); Thu, 17 Jan 2019 07:02:23 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 17 Jan 2019 13:02:21 +0100 From: Roman Penyaev Subject: Re: [PATCH 05/15] Add io_uring IO interface In-Reply-To: <20190116175003.17880-6-axboe@kernel.dk> References: <20190116175003.17880-1-axboe@kernel.dk> <20190116175003.17880-6-axboe@kernel.dk> Message-ID: <362738449bd3f83d18cb1056acc9b875@suse.de> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Jens Axboe Cc: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org, hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, linux-block-owner@vger.kernel.org Message-ID: <20190117120221.n403CmsUkvO7yRIM7SpguT3blzKngUpDV0maCfq86mI@z> Hi Jens, On 2019-01-16 18:49, Jens Axboe wrote: [...] > +static void *io_mem_alloc(size_t size) > +{ > + gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP > | > + __GFP_NORETRY; > + > + return (void *) __get_free_pages(gfp_flags, get_order(size)); Since these pages are shared between kernel and userspace, do we need to care about d-cache aliasing on armv6 (or other "strange" archs which I've never seen) with vivt or vipt cpu caches? E.g. vmalloc_user() targets this problem by aligning kernel address on SHMLBA, so no flush_dcache_page() is required. -- Roman