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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 326CEC433FE for ; Mon, 14 Nov 2022 10:55:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235971AbiKNKza (ORCPT ); Mon, 14 Nov 2022 05:55:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51392 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235948AbiKNKz0 (ORCPT ); Mon, 14 Nov 2022 05:55:26 -0500 Received: from mail-io1-f69.google.com (mail-io1-f69.google.com [209.85.166.69]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E32B4A19F for ; Mon, 14 Nov 2022 02:55:22 -0800 (PST) Received: by mail-io1-f69.google.com with SMTP id r197-20020a6b8fce000000b006c3fc33424dso5572361iod.5 for ; Mon, 14 Nov 2022 02:55:22 -0800 (PST) X-Google-DKIM-Signature: v=1; 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charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: possible deadlock in show_map_vma ============================================ WARNING: possible recursive locking detected 6.1.0-rc4-next-20221111-syzkaller-dirty #0 Not tainted -------------------------------------------- syz-executor.0/5772 is trying to acquire lock: ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline] ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: show_map_vma+0x1dd/0x8a0 fs/proc/task_mmu.c:298 but task is already holding lock: ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline] ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: m_start+0x1d6/0x670 fs/proc/task_mmu.c:162 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&mm->mmap_lock); lock(&mm->mmap_lock); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by syz-executor.0/5772: #0: ffff88801d4c28b8 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xdf/0x1280 fs/seq_file.c:182 #1: ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline] #1: ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: m_start+0x1d6/0x670 fs/proc/task_mmu.c:162 stack backtrace: CPU: 1 PID: 5772 Comm: syz-executor.0 Not tainted 6.1.0-rc4-next-20221111-syzkaller-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2990 [inline] check_deadlock kernel/locking/lockdep.c:3033 [inline] validate_chain kernel/locking/lockdep.c:3818 [inline] __lock_acquire.cold+0x116/0x3a7 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633 down_read_killable+0x9b/0x490 kernel/locking/rwsem.c:1532 mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline] show_map_vma+0x1dd/0x8a0 fs/proc/task_mmu.c:298 show_smap+0xe4/0x490 fs/proc/task_mmu.c:873 traverse.part.0+0xcf/0x5f0 fs/seq_file.c:111 traverse fs/seq_file.c:101 [inline] seq_read_iter+0x90f/0x1280 fs/seq_file.c:195 seq_read+0x16d/0x210 fs/seq_file.c:162 do_loop_readv_writev fs/read_write.c:756 [inline] do_loop_readv_writev fs/read_write.c:743 [inline] do_iter_read+0x4f8/0x750 fs/read_write.c:798 vfs_readv+0xe5/0x150 fs/read_write.c:916 do_preadv fs/read_write.c:1008 [inline] __do_sys_preadv fs/read_write.c:1058 [inline] __se_sys_preadv fs/read_write.c:1053 [inline] __x64_sys_preadv+0x22b/0x310 fs/read_write.c:1053 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fdc27c8b639 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdc28980168 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 00007fdc27dabf80 RCX: 00007fdc27c8b639 RDX: 0000000000000001 RSI: 00000000200006c0 RDI: 0000000000000003 RBP: 00007fdc27ce67e1 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000fffffffe R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc20c7d9af R14: 00007fdc28980300 R15: 0000000000022000 Tested on: commit: f8f60f32 Add linux-next specific files for 20221111 git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git console output: https://syzkaller.appspot.com/x/log.txt?x=13a0e2f1880000 kernel config: https://syzkaller.appspot.com/x/.config?x=85ba52c07cd97289 dashboard link: https://syzkaller.appspot.com/bug?extid=62ed954113bf02c79f74 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 patch: https://syzkaller.appspot.com/x/patch.diff?x=1069e0f1880000