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xfstest generic/587 reports a deadlock issue as below:
======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc1 #69 Not tainted
------------------------------------------------------
repquota/8606 is trying to acquire lock:
ffff888022ac9320 (&sb->s_type->i_mutex_key#18){+.+.}-{3:3}, at: f2fs_quota_sync+0x207/0x300 [f2fs]
but task is already holding lock:
ffff8880084bcde8 (&sbi->quota_sem){.+.+}-{3:3}, at: f2fs_quota_sync+0x59/0x300 [f2fs]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&sbi->quota_sem){.+.+}-{3:3}:
__lock_acquire+0x648/0x10b0
lock_acquire+0x128/0x470
down_read+0x3b/0x2a0
f2fs_quota_sync+0x59/0x300 [f2fs]
f2fs_quota_on+0x48/0x100 [f2fs]
do_quotactl+0x5e3/0xb30
__x64_sys_quotactl+0x23a/0x4e0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #1 (&sbi->cp_rwsem){++++}-{3:3}:
__lock_acquire+0x648/0x10b0
lock_acquire+0x128/0x470
down_read+0x3b/0x2a0
f2fs_unlink+0x353/0x670 [f2fs]
vfs_unlink+0x1c7/0x380
do_unlinkat+0x413/0x4b0
__x64_sys_unlinkat+0x50/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #0 (&sb->s_type->i_mutex_key#18){+.+.}-{3:3}:
check_prev_add+0xdc/0xb30
validate_chain+0xa67/0xb20
__lock_acquire+0x648/0x10b0
lock_acquire+0x128/0x470
down_write+0x39/0xc0
f2fs_quota_sync+0x207/0x300 [f2fs]
do_quotactl+0xaff/0xb30
__x64_sys_quotactl+0x23a/0x4e0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
&sb->s_type->i_mutex_key#18 --> &sbi->cp_rwsem --> &sbi->quota_sem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&sbi->quota_sem);
lock(&sbi->cp_rwsem);
lock(&sbi->quota_sem);
lock(&sb->s_type->i_mutex_key#18);
*** DEADLOCK ***
3 locks held by repquota/8606:
#0: ffff88801efac0e0 (&type->s_umount_key#53){++++}-{3:3}, at: user_get_super+0xd9/0x190
#1: ffff8880084bc380 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_quota_sync+0x3e/0x300 [f2fs]
#2: ffff8880084bcde8 (&sbi->quota_sem){.+.+}-{3:3}, at: f2fs_quota_sync+0x59/0x300 [f2fs]
stack backtrace:
CPU: 6 PID: 8606 Comm: repquota Not tainted 5.14.0-rc1 #69
Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
Call Trace:
dump_stack_lvl+0xce/0x134
dump_stack+0x17/0x20
print_circular_bug.isra.0.cold+0x239/0x253
check_noncircular+0x1be/0x1f0
check_prev_add+0xdc/0xb30
validate_chain+0xa67/0xb20
__lock_acquire+0x648/0x10b0
lock_acquire+0x128/0x470
down_write+0x39/0xc0
f2fs_quota_sync+0x207/0x300 [f2fs]
do_quotactl+0xaff/0xb30
__x64_sys_quotactl+0x23a/0x4e0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f883b0b4efe
The root cause is ABBA deadlock of inode lock and cp_rwsem,
reorder locks in f2fs_quota_sync() as below to fix this issue:
- lock inode
- lock cp_rwsem
- lock quota_sem
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
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| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
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| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.