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Message-ID: <0000000000007e66d506157ad1bc@google.com>
Date: Sat, 06 Apr 2024 22:18:25 -0700
From: syzbot <syzbot+8ef337b733667f9a7ec8@...kaller.appspotmail.com>
To: agruenba@...hat.com, gfs2@...ts.linux.dev, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [gfs2?] possible deadlock in do_qc

Hello,

syzbot found the following issue on:

HEAD commit:    707081b61156 Merge branch 'for-next/core', remote-tracking..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=15db6719180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=caeac3f3565b057a
dashboard link: https://syzkaller.appspot.com/bug?extid=8ef337b733667f9a7ec8
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6cad68bf7532/disk-707081b6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1a27e5400778/vmlinux-707081b6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/67dfc53755d0/Image-707081b6.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8ef337b733667f9a7ec8@...kaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.8.0-rc7-syzkaller-g707081b61156 #0 Not tainted
------------------------------------------------------
syz-executor.3/6998 is trying to acquire lock:
ffff0000ccd04ae8 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xac/0x5c8 fs/gfs2/quota.c:720

but task is already holding lock:
ffff0000db995688 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1529 [inline]
ffff0000db995688 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x1f58/0x2f7c fs/gfs2/bmap.c:1852

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ip->i_rw_mutex){++++}-{3:3}:
       down_read+0x58/0x2fc kernel/locking/rwsem.c:1526
       __gfs2_iomap_get+0x138/0x1058 fs/gfs2/bmap.c:859
       gfs2_iomap_get+0xd8/0x154 fs/gfs2/bmap.c:1413
       bh_get+0x1ec/0x690 fs/gfs2/quota.c:417
       qdsb_get+0x1c8/0x30c fs/gfs2/quota.c:566
       gfs2_quota_hold+0x16c/0x560 fs/gfs2/quota.c:646
       punch_hole+0xc10/0x2f7c fs/gfs2/bmap.c:1813
       gfs2_iomap_end+0x448/0x618 fs/gfs2/bmap.c:1174
       iomap_iter+0x1f4/0x1018 fs/iomap/iter.c:79
       iomap_file_buffered_write+0x968/0xb30 fs/iomap/buffered-io.c:976
       gfs2_file_buffered_write+0x468/0x76c fs/gfs2/file.c:1059
       gfs2_file_write_iter+0x79c/0xdb0 fs/gfs2/file.c:1163
       call_write_iter include/linux/fs.h:2087 [inline]
       new_sync_write fs/read_write.c:497 [inline]
       vfs_write+0x968/0xc3c fs/read_write.c:590
       ksys_write+0x15c/0x26c fs/read_write.c:643
       __do_sys_write fs/read_write.c:655 [inline]
       __se_sys_write fs/read_write.c:652 [inline]
       __arm64_sys_write+0x7c/0x90 fs/read_write.c:652
       __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #0 (&sdp->sd_quota_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x3384/0x763c kernel/locking/lockdep.c:5137
       lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5754
       __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
       __mutex_lock kernel/locking/mutex.c:752 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
       do_qc+0xac/0x5c8 fs/gfs2/quota.c:720
       gfs2_quota_change+0x238/0x728 fs/gfs2/quota.c:1315
       punch_hole+0x2a30/0x2f7c fs/gfs2/bmap.c:1953
       gfs2_iomap_end+0x448/0x618 fs/gfs2/bmap.c:1174
       iomap_iter+0x1f4/0x1018 fs/iomap/iter.c:79
       iomap_file_buffered_write+0x968/0xb30 fs/iomap/buffered-io.c:976
       gfs2_file_buffered_write+0x468/0x76c fs/gfs2/file.c:1059
       gfs2_file_write_iter+0x79c/0xdb0 fs/gfs2/file.c:1163
       call_write_iter include/linux/fs.h:2087 [inline]
       new_sync_write fs/read_write.c:497 [inline]
       vfs_write+0x968/0xc3c fs/read_write.c:590
       ksys_write+0x15c/0x26c fs/read_write.c:643
       __do_sys_write fs/read_write.c:655 [inline]
       __se_sys_write fs/read_write.c:652 [inline]
       __arm64_sys_write+0x7c/0x90 fs/read_write.c:652
       __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ip->i_rw_mutex);
                               lock(&sdp->sd_quota_mutex);
                               lock(&ip->i_rw_mutex);
  lock(&sdp->sd_quota_mutex);

 *** DEADLOCK ***

6 locks held by syz-executor.3/6998:
 #0: ffff0000d5936348 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x218/0x2a4 fs/file.c:1191
 #1: ffff0000f2b02420 (sb_writers#24){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2794 [inline]
 #1: ffff0000f2b02420 (sb_writers#24){.+.+}-{0:0}, at: vfs_write+0x368/0xc3c fs/read_write.c:586
 #2: ffff0000db9951f0 (&sb->s_type->i_mutex_key#27){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff0000db9951f0 (&sb->s_type->i_mutex_key#27){+.+.}-{3:3}, at: gfs2_file_write_iter+0x2ac/0xdb0 fs/gfs2/file.c:1114
 #3: ffff0000f2b02610 (sb_internal#6){.+.+}-{0:0}, at: gfs2_trans_begin+0x8c/0x100 fs/gfs2/trans.c:118
 #4: ffff0000ccd05060 (&sdp->sd_log_flush_lock){++++}-{3:3}, at: __gfs2_trans_begin+0x510/0x908 fs/gfs2/trans.c:87
 #5: ffff0000db995688 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1529 [inline]
 #5: ffff0000db995688 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x1f58/0x2f7c fs/gfs2/bmap.c:1852

stack backtrace:
CPU: 0 PID: 6998 Comm: syz-executor.3 Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:291
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:298
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
 dump_stack+0x1c/0x28 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060
 check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x3384/0x763c kernel/locking/lockdep.c:5137
 lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5754
 __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
 __mutex_lock kernel/locking/mutex.c:752 [inline]
 mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
 do_qc+0xac/0x5c8 fs/gfs2/quota.c:720
 gfs2_quota_change+0x238/0x728 fs/gfs2/quota.c:1315
 punch_hole+0x2a30/0x2f7c fs/gfs2/bmap.c:1953
 gfs2_iomap_end+0x448/0x618 fs/gfs2/bmap.c:1174
 iomap_iter+0x1f4/0x1018 fs/iomap/iter.c:79
 iomap_file_buffered_write+0x968/0xb30 fs/iomap/buffered-io.c:976
 gfs2_file_buffered_write+0x468/0x76c fs/gfs2/file.c:1059
 gfs2_file_write_iter+0x79c/0xdb0 fs/gfs2/file.c:1163
 call_write_iter include/linux/fs.h:2087 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0x968/0xc3c fs/read_write.c:590
 ksys_write+0x15c/0x26c fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:652
 __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

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