Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932938AbdGTBPN (ORCPT ); Wed, 19 Jul 2017 21:15:13 -0400 Received: from mail-yw0-f196.google.com ([209.85.161.196]:35585 "EHLO mail-yw0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753627AbdGTBPL (ORCPT ); Wed, 19 Jul 2017 21:15:11 -0400 MIME-Version: 1.0 In-Reply-To: <20170719135014.fdc882d1e28fd130104eff5d@linux-foundation.org> References: <1500461043-7414-1-git-send-email-zhaoyang.huang@spreadtrum.com> <20170719135014.fdc882d1e28fd130104eff5d@linux-foundation.org> From: Zhaoyang Huang Date: Thu, 20 Jul 2017 09:15:10 +0800 Message-ID: Subject: Re: [PATCH] mm/vmalloc: add vm_struct for vm_map_ram area To: Andrew Morton Cc: zhaoyang.huang@spreadtrum.com, Michal Hocko , Ingo Molnar , zijun_hu , Vlastimil Babka , Thomas Garnier , "Kirill A. Shutemov" , Andrey Ryabinin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, zijun_hu@zoho.com, ming.ling@spreadtrum.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3071 Lines: 74 On Thu, Jul 20, 2017 at 4:50 AM, Andrew Morton wrote: > On Wed, 19 Jul 2017 18:44:03 +0800 Zhaoyang Huang wrote: > >> /proc/vmallocinfo will not show the area allocated by vm_map_ram, which >> will make confusion when debug. Add vm_struct for them and show them in >> proc. >> > > Please provide sample /proc/vmallocinfo so we can better understand the > proposal. Is there a means by which people can determine that a > particular area is from vm_map_ram()? I don't think so. Should there > be? Here is the part of vmallocinfo, the line start with '>' are the ones allocated by vm_map_ram. xxxx:/ # cat /proc/vmallocinfo 0xffffff8000a5f000-0xffffff8000abb000 376832 load_module+0x1004/0x1e98 pages=91 vmalloc 0xffffff8000ac6000-0xffffff8000ad2000 49152 load_module+0x1004/0x1e98 pages=11 vmalloc 0xffffff8000ad8000-0xffffff8000ade000 24576 load_module+0x1004/0x1e98 pages=5 vmalloc 0xffffff8008000000-0xffffff8008002000 8192 of_iomap+0x4c/0x68 phys=12001000 ioremap 0xffffff8008002000-0xffffff8008004000 8192 of_iomap+0x4c/0x68 phys=40356000 ioremap 0xffffff8008004000-0xffffff8008007000 12288 of_iomap+0x4c/0x68 phys=12002000 ioremap 0xffffff8008008000-0xffffff800800d000 20480 of_sprd_gates_clk_setup_with_ops+0x88/0x2a8 phys=402b0000 ioremap 0xffffff800800e000-0xffffff8008010000 8192 of_iomap+0x4c/0x68 phys=40356000 ioremap ... >0xffffff800c5a3000-0xffffff800c5ec000 299008 shmem_ram_vmap+0xe8/0x1a0 0xffffff800c5fe000-0xffffff800c600000 8192 kbasep_js_policy_ctx_has_priority+0x254/0xdb0 [mali_kbase] pages=1 vmalloc 0xffffff800c600000-0xffffff800c701000 1052672 of_iomap+0x4c/0x68 phys=60d00000 ioremap >0xffffff800c701000-0xffffff800c742000 266240 shmem_ram_vmap+0xe8/0x1a0 0xffffff800c74e000-0xffffff800c750000 8192 kbasep_js_policy_ctx_has_priority+0x2cc/0xdb0 [mali_kbase] pages=1 vmalloc ... > >> >> ... >> >> @@ -1173,6 +1178,12 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t pro >> addr = (unsigned long)mem; >> } else { >> struct vmap_area *va; >> + struct vm_struct *area; >> + >> + area = kzalloc_node(sizeof(*area), GFP_KERNEL, node); >> + if (unlikely(!area)) >> + return NULL; > > Allocating a vm_struct for each vm_map_ram area is a cost. And we're > doing this purely for /proc/vmallocinfo. I think I'll need more > persuading to convince me that this is a good tradeoff, given that > *every* user will incur this cost, and approximately 0% of them will > ever use /proc/vmallocinfo. > > So... do we *really* need this? If so, why? The motivation of this commit comes from one practical debug, that is, vmalloc failed by one driver's allocating a huge area by vm_map_ram, which can not be traced by cat /proc/vmallocinfo. We have to add a lot of printk and dump_stack to get more information. I don't think the vm_struct cost too much memory, just imagine that the area got by vmalloc or ioremap instead, you have to pay for it as well. >