From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8386C2BD09 for ; Fri, 6 Dec 2019 16:21:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B6EE024659 for ; Fri, 6 Dec 2019 16:21:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726350AbfLFQVJ (ORCPT ); Fri, 6 Dec 2019 11:21:09 -0500 Received: from relay.sw.ru ([185.231.240.75]:51204 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726258AbfLFQVJ (ORCPT ); Fri, 6 Dec 2019 11:21:09 -0500 Received: from dhcp-172-16-25-5.sw.ru ([172.16.25.5]) by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1idGLe-00008F-Rf; Fri, 06 Dec 2019 19:20:55 +0300 From: Andrey Ryabinin Subject: Re: [PATCH 2/2] kasan: Don't allocate page tables in kasan_release_vmalloc() To: Andrew Morton Cc: Alexander Potapenko , Dmitry Vyukov , kasan-dev@googlegroups.com, Daniel Axtens , Qian Cai , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20191204204534.32202-1-aryabinin@virtuozzo.com> <20191204204534.32202-2-aryabinin@virtuozzo.com> <20191204142256.567b143cfde572acd804544a@linux-foundation.org> Message-ID: <1d53f0a3-a37e-72ca-fc69-c34e4f5023b7@virtuozzo.com> Date: Fri, 6 Dec 2019 19:20:39 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20191204142256.567b143cfde572acd804544a@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/5/19 1:22 AM, Andrew Morton wrote: > On Wed, 4 Dec 2019 23:45:34 +0300 Andrey Ryabinin wrote: > >> The purpose of kasan_release_vmalloc() is to unmap and deallocate shadow >> memory. The usage of apply_to_page_range() isn't suitable in that scenario >> because it allocates pages to fill missing page tables entries. >> This also cause sleep in atomic bug: >> >> BUG: sleeping function called from invalid context at mm/page_alloc.c:4681 >> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 15087, name: >> >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x199/0x216 lib/dump_stack.c:118 >> ___might_sleep.cold.97+0x1f5/0x238 kernel/sched/core.c:6800 >> __might_sleep+0x95/0x190 kernel/sched/core.c:6753 >> prepare_alloc_pages mm/page_alloc.c:4681 [inline] >> __alloc_pages_nodemask+0x3cd/0x890 mm/page_alloc.c:4730 >> alloc_pages_current+0x10c/0x210 mm/mempolicy.c:2211 >> alloc_pages include/linux/gfp.h:532 [inline] >> __get_free_pages+0xc/0x40 mm/page_alloc.c:4786 >> __pte_alloc_one_kernel include/asm-generic/pgalloc.h:21 [inline] >> pte_alloc_one_kernel include/asm-generic/pgalloc.h:33 [inline] >> __pte_alloc_kernel+0x1d/0x200 mm/memory.c:459 >> apply_to_pte_range mm/memory.c:2031 [inline] >> apply_to_pmd_range mm/memory.c:2068 [inline] >> apply_to_pud_range mm/memory.c:2088 [inline] >> apply_to_p4d_range mm/memory.c:2108 [inline] >> apply_to_page_range+0x77d/0xa00 mm/memory.c:2133 >> kasan_release_vmalloc+0xa7/0xc0 mm/kasan/common.c:970 >> __purge_vmap_area_lazy+0xcbb/0x1f30 mm/vmalloc.c:1313 >> try_purge_vmap_area_lazy mm/vmalloc.c:1332 [inline] >> free_vmap_area_noflush+0x2ca/0x390 mm/vmalloc.c:1368 >> free_unmap_vmap_area mm/vmalloc.c:1381 [inline] >> remove_vm_area+0x1cc/0x230 mm/vmalloc.c:2209 >> vm_remove_mappings mm/vmalloc.c:2236 [inline] >> __vunmap+0x223/0xa20 mm/vmalloc.c:2299 >> __vfree+0x3f/0xd0 mm/vmalloc.c:2356 >> __vmalloc_area_node mm/vmalloc.c:2507 [inline] >> __vmalloc_node_range+0x5d5/0x810 mm/vmalloc.c:2547 >> __vmalloc_node mm/vmalloc.c:2607 [inline] >> __vmalloc_node_flags mm/vmalloc.c:2621 [inline] >> vzalloc+0x6f/0x80 mm/vmalloc.c:2666 >> alloc_one_pg_vec_page net/packet/af_packet.c:4233 [inline] >> alloc_pg_vec net/packet/af_packet.c:4258 [inline] >> packet_set_ring+0xbc0/0x1b50 net/packet/af_packet.c:4342 >> packet_setsockopt+0xed7/0x2d90 net/packet/af_packet.c:3695 >> __sys_setsockopt+0x29b/0x4d0 net/socket.c:2117 >> __do_sys_setsockopt net/socket.c:2133 [inline] >> __se_sys_setsockopt net/socket.c:2130 [inline] >> __x64_sys_setsockopt+0xbe/0x150 net/socket.c:2130 >> do_syscall_64+0xfa/0x780 arch/x86/entry/common.c:294 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Why is this warning happening? Some lock held? If so, which one? spin_lock(&free_vmap_area_lock); > >> Add kasan_unmap_page_range() which skips empty page table entries instead >> of allocating them. > > Adding an open-coded range walker is unfortunate. Did you consider > generalizing apply_to_page_range() for this purpose? I did - it looks > messy. > > Somewhat. I guess adding another arg to > apply_to_p4d_range...apply_to_pte_range wouldn't kill us. I wonder if > there would be other sites which could utilize the additional control. > >