linux-kernel - Re: [PATCH 2/2] fsnotify: allow sleepable child flag update

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Message-ID: <202210271500.731e3808-yujie.liu@intel.com>
Date:   Thu, 27 Oct 2022 15:50:17 +0800
From:   kernel test robot <yujie.liu@...el.com>
To:     Stephen Brennan <stephen.s.brennan@...cle.com>
CC:     <oe-lkp@...ts.linux.dev>, <lkp@...el.com>,
        <linux-fsdevel@...r.kernel.org>, Jan Kara <jack@...e.cz>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Amir Goldstein <amir73il@...il.com>,
        <linux-kernel@...r.kernel.org>,
        Stephen Brennan <stephen.s.brennan@...cle.com>
Subject: Re: [PATCH 2/2] fsnotify: allow sleepable child flag update

Greeting,

FYI, we noticed WARNING:possible_recursive_locking_detected due to commit (built with clang-14):

commit: bed2685d9557ff9a7705f4172651a138e5f705af ("[PATCH 2/2] fsnotify: allow sleepable child flag update")
url: https://github.com/intel-lab-lkp/linux/commits/Stephen-Brennan/fsnotify-Protect-i_fsnotify_mask-and-child-flags-with-inode-rwsem/20221018-131326
base: https://git.kernel.org/cgit/linux/kernel/git/jack/linux-fs.git fsnotify
patch link: https://lore.kernel.org/linux-fsdevel/20221018041233.376977-3-stephen.s.brennan@oracle.com
patch subject: [PATCH 2/2] fsnotify: allow sleepable child flag update

in testcase: boot

on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


[   31.979147][    T1]
[   31.979446][    T1] ============================================
[   31.980051][    T1] WARNING: possible recursive locking detected
[   31.980674][    T1] 6.0.0-rc4-00066-gbed2685d9557 #1 Not tainted
[   31.981286][    T1] --------------------------------------------
[   31.981889][    T1] systemd/1 is trying to acquire lock:
[   31.982432][    T1] ffff88813f542510 (&dentry->d_lock){+.+.}-{2:2}, at: lockref_get+0xd/0x80
[   31.983314][    T1]
[   31.983314][    T1] but task is already holding lock:
[   31.984040][    T1] ffff888100441b18 (&dentry->d_lock){+.+.}-{2:2}, at: __fsnotify_update_child_dentry_flags+0x85/0x2c0
[   31.985132][    T1]
[   31.985132][    T1] other info that might help us debug this:
[   31.985967][    T1]  Possible unsafe locking scenario:
[   31.985967][    T1]
[   31.986694][    T1]        CPU0
[   31.987025][    T1]        ----
[   31.987366][    T1]   lock(&dentry->d_lock);
[   31.987828][    T1]   lock(&dentry->d_lock);
[   31.988283][    T1]
[   31.988283][    T1]  *** DEADLOCK ***
[   31.988283][    T1]
[   31.989061][    T1]  May be due to missing lock nesting notation
[   31.989061][    T1]
[   31.989888][    T1] 3 locks held by systemd/1:
[   31.990361][    T1]  #0: ffff88815249e128 (&group->mark_mutex){+.+.}-{3:3}, at: __x64_sys_inotify_add_watch+0x2fc/0xc00
[   31.991473][    T1]  #1: ffff888100480af8 (&sb->s_type->i_mutex_key){++++}-{3:3}, at: fsnotify_recalc_mask+0xf1/0x1c0
[   31.992528][    T1]  #2: ffff888100441b18 (&dentry->d_lock){+.+.}-{2:2}, at: __fsnotify_update_child_dentry_flags+0x85/0x2c0
[   31.993671][    T1]
[   31.993671][    T1] stack backtrace:
[   31.994260][    T1] CPU: 0 PID: 1 Comm: systemd Not tainted 6.0.0-rc4-00066-gbed2685d9557 #1 1afcec0fe797aeed18cb95313bac4a75fb6852d3
[   31.995440][    T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014
[   31.996441][    T1] Call Trace:
[   31.996791][    T1]  <TASK>
[   31.997101][    T1]  dump_stack_lvl+0x6a/0x100
[   31.997590][    T1]  __lock_acquire+0x1110/0x7480
[   31.998105][    T1]  ? mark_lock+0x9a/0x380
[   31.998560][    T1]  ? mark_held_locks+0xad/0x1c0
[   31.999056][    T1]  ? lockdep_hardirqs_on_prepare+0x1a8/0x400
[   31.999650][    T1]  ? asm_sysvec_apic_timer_interrupt+0x1a/0x20
[   32.000276][    T1]  lock_acquire+0x177/0x480
[   32.000739][    T1]  ? lockref_get+0xd/0x80
[   32.001178][    T1]  _raw_spin_lock+0x2f/0x40
[   32.001656][    T1]  ? lockref_get+0xd/0x80
[   32.002093][    T1]  lockref_get+0xd/0x80
[   32.002529][    T1]  __fsnotify_update_child_dentry_flags+0x142/0x2c0
[   32.003178][    T1]  fsnotify_recalc_mask+0x126/0x1c0
[   32.003711][    T1]  fsnotify_add_mark_locked+0xd9e/0x1280
[   32.004292][    T1]  __x64_sys_inotify_add_watch+0x755/0xc00
[   32.004898][    T1]  ? syscall_enter_from_user_mode+0x26/0x180
[   32.005660][    T1]  do_syscall_64+0x6d/0xc0
[   32.006125][    T1]  entry_SYSCALL_64_after_hwframe+0x46/0xb0
[   32.006735][    T1] RIP: 0033:0x7f839dd0a8f7
[   32.007188][    T1] Code: f0 ff ff 73 01 c3 48 8b 0d 96 f5 0b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 fe 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 69 f5 0b 00 f7 d8 64 89 01 48
[   32.009103][    T1] RSP: 002b:00007ffe52095c98 EFLAGS: 00000202 ORIG_RAX: 00000000000000fe
[   32.009945][    T1] RAX: ffffffffffffffda RBX: 0000555bc72cf930 RCX: 00007f839dd0a8f7
[   32.010685][    T1] RDX: 0000000000000d84 RSI: 0000555bc72cf930 RDI: 000000000000001a
[   32.011469][    T1] RBP: 0000555bc72cf931 R08: 00000000fe000000 R09: 0000555bc72a1e90
[   32.012266][    T1] R10: 00007ffe52095c2c R11: 0000000000000202 R12: 0000000000000000
[   32.012976][    T1] R13: 0000555bc72a1e90 R14: 0000000000000d84 R15: 0000555bc72cf930
[   32.013705][    T1]  </TASK>


If you fix the issue, kindly add following tag
| Reported-by: kernel test robot <yujie.liu@...el.com>
| Link: https://lore.kernel.org/oe-lkp/202210271500.731e3808-yujie.liu@intel.com


To reproduce:

        # build kernel
	cd linux
	cp config-6.0.0-rc4-00066-gbed2685d9557 .config
	make HOSTCC=clang-14 CC=clang-14 ARCH=x86_64 olddefconfig prepare modules_prepare bzImage modules
	make HOSTCC=clang-14 CC=clang-14 ARCH=x86_64 INSTALL_MOD_PATH=<mod-install-dir> modules_install
	cd <mod-install-dir>
	find lib/ | cpio -o -H newc --quiet | gzip > modules.cgz


        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> -m modules.cgz job-script # job-script is attached in this email

        # if come across any failure that blocks the test,
        # please remove ~/.lkp and /lkp dir to run from a clean state.


-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

View attachment "config-6.0.0-rc4-00066-gbed2685d9557" of type "text/plain" (169925 bytes)

View attachment "job-script" of type "text/plain" (4967 bytes)

Download attachment "dmesg.xz" of type "application/x-xz" (57000 bytes)