syzbot


possible deadlock in ext4_evict_inode

Status: auto-obsoleted due to no activity on 2023/10/19 10:40
Reported-by: syzbot+ac8ae3af0f091d178924@syzkaller.appspotmail.com
First crash: 371d, last: 261d
Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ext4_evict_inode (2) ext4 18 378d 554d 0/26 auto-obsoleted due to no activity on 2023/07/14 13:24
linux-5.15 possible deadlock in ext4_evict_inode (2) 2 16d 21d 0/3 upstream: reported on 2024/03/07 16:36
upstream possible deadlock in ext4_evict_inode (3) ext4 2 3d04h 42d 0/26 upstream: reported on 2024/02/15 21:18
upstream possible deadlock in ext4_evict_inode ext4 syz error error 38 1992d 2030d 15/26 fixed on 2020/05/22 17:31
linux-6.1 possible deadlock in ext4_evict_inode (2) 1 114d 114d 0/3 auto-obsoleted due to no activity on 2024/03/15 02:58
linux-5.15 possible deadlock in ext4_evict_inode 2 363d 367d 0/3 auto-obsoleted due to no activity on 2023/07/30 00:10

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.1.38-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/30896 is trying to acquire lock:
ffff888143380650 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1832 [inline]
ffff888143380650 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:1954 [inline]
ffff888143380650 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x46d/0x1150 fs/ext4/inode.c:240

but task is already holding lock:
ffff888143382b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x314/0x12f0 fs/ext4/migrate.c:437

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&sbi->s_writepages_rwsem){++++}-{0:0}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
       percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
       ext4_writepages+0x1e5/0x3de0 fs/ext4/inode.c:2701
       do_writepages+0x3a2/0x670 mm/page-writeback.c:2469
       filemap_fdatawrite_wbc+0x121/0x180 mm/filemap.c:388
       __filemap_fdatawrite_range mm/filemap.c:421 [inline]
       filemap_write_and_wait_range+0x1a4/0x290 mm/filemap.c:674
       __iomap_dio_rw+0xb38/0x2240 fs/iomap/direct-io.c:573
       iomap_dio_rw+0x42/0xa0 fs/iomap/direct-io.c:690
       ext4_dio_write_iter fs/ext4/file.c:587 [inline]
       ext4_file_write_iter+0x14ec/0x18f0 fs/ext4/file.c:698
       do_iter_write+0x6e6/0xc50 fs/read_write.c:861
       iter_file_splice_write+0x806/0xfa0 fs/splice.c:686
       do_splice_from fs/splice.c:764 [inline]
       direct_splice_actor+0xe3/0x1c0 fs/splice.c:931
       splice_direct_to_actor+0x4c0/0xbd0 fs/splice.c:886
       do_splice_direct+0x27f/0x3c0 fs/splice.c:974
       do_sendfile+0x61c/0xff0 fs/read_write.c:1255
       __do_sys_sendfile64 fs/read_write.c:1323 [inline]
       __se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1309
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #2 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
       down_read+0x43/0x2e0 kernel/locking/rwsem.c:1520
       inode_lock_shared include/linux/fs.h:766 [inline]
       ext4_bmap+0x4b/0x410 fs/ext4/inode.c:3174
       bmap+0xa1/0xd0 fs/inode.c:1798
       jbd2_journal_bmap fs/jbd2/journal.c:977 [inline]
       __jbd2_journal_erase fs/jbd2/journal.c:1789 [inline]
       jbd2_journal_flush+0x5b5/0xc40 fs/jbd2/journal.c:2492
       ext4_ioctl_checkpoint fs/ext4/ioctl.c:1083 [inline]
       __ext4_ioctl fs/ext4/ioctl.c:1591 [inline]
       ext4_ioctl+0x39e0/0x5f70 fs/ext4/ioctl.c:1611
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
       __mutex_lock_common+0x1d4/0x2520 kernel/locking/mutex.c:603
       mutex_lock_io_nested+0x43/0x60 kernel/locking/mutex.c:833
       __jbd2_log_wait_for_space+0x213/0x760 fs/jbd2/checkpoint.c:110
       add_transaction_credits+0x94c/0xc00 fs/jbd2/transaction.c:298
       start_this_handle+0x747/0x1640 fs/jbd2/transaction.c:422
       jbd2__journal_start+0x2d1/0x5c0 fs/jbd2/transaction.c:520
       __ext4_journal_start_sb+0x19b/0x410 fs/ext4/ext4_jbd2.c:105
       __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
       ext4_evict_inode+0x8dc/0x1150 fs/ext4/inode.c:251
       evict+0x2a4/0x620 fs/inode.c:664
       __dentry_kill+0x436/0x650 fs/dcache.c:607
       dentry_kill+0xbb/0x290
       dput+0x1ef/0x420 fs/dcache.c:913
       path_put+0x35/0x60 fs/namei.c:558
       free_fs_struct fs/fs_struct.c:91 [inline]
       exit_fs+0xe1/0x140 fs/fs_struct.c:108
       do_exit+0x6e4/0x2300 kernel/exit.c:865
       __do_sys_exit kernel/exit.c:986 [inline]
       __se_sys_exit kernel/exit.c:984 [inline]
       __x64_sys_exit+0x3c/0x40 kernel/exit.c:984
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (sb_internal){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3098 [inline]
       check_prevs_add kernel/locking/lockdep.c:3217 [inline]
       validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
       percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
       __sb_start_write include/linux/fs.h:1832 [inline]
       sb_start_intwrite include/linux/fs.h:1954 [inline]
       ext4_evict_inode+0x46d/0x1150 fs/ext4/inode.c:240
       evict+0x2a4/0x620 fs/inode.c:664
       ext4_ext_migrate+0x100b/0x12f0 fs/ext4/migrate.c:587
       __ext4_ioctl fs/ext4/ioctl.c:1393 [inline]
       ext4_ioctl+0x1dea/0x5f70 fs/ext4/ioctl.c:1611
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
  sb_internal --> &sb->s_type->i_mutex_key#8 --> &sbi->s_writepages_rwsem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sbi->s_writepages_rwsem);
                               lock(&sb->s_type->i_mutex_key#8);
                               lock(&sbi->s_writepages_rwsem);
  lock(sb_internal);

 *** DEADLOCK ***

3 locks held by syz-executor.2/30896:
 #0: ffff888143380460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
 #1: ffff8880330eac20 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
 #1: ffff8880330eac20 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1392 [inline]
 #1: ffff8880330eac20 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_ioctl+0x1de2/0x5f70 fs/ext4/ioctl.c:1611
 #2: ffff888143382b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x314/0x12f0 fs/ext4/migrate.c:437

stack backtrace:
CPU: 1 PID: 30896 Comm: syz-executor.2 Not tainted 6.1.38-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3098 [inline]
 check_prevs_add kernel/locking/lockdep.c:3217 [inline]
 validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
 percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
 __sb_start_write include/linux/fs.h:1832 [inline]
 sb_start_intwrite include/linux/fs.h:1954 [inline]
 ext4_evict_inode+0x46d/0x1150 fs/ext4/inode.c:240
 evict+0x2a4/0x620 fs/inode.c:664
 ext4_ext_migrate+0x100b/0x12f0 fs/ext4/migrate.c:587
 __ext4_ioctl fs/ext4/ioctl.c:1393 [inline]
 ext4_ioctl+0x1dea/0x5f70 fs/ext4/ioctl.c:1611
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcb5b08c389
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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:00007fcb5bd9b168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fcb5b1ac120 RCX: 00007fcb5b08c389
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000004
RBP: 00007fcb5b0d7493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd9806350f R14: 00007fcb5bd9b300 R15: 0000000000022000
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/07/11 10:40 linux-6.1.y 61fd484b2cf6 f8780940 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_evict_inode
2023/03/24 01:38 linux-6.1.y e3a87a10f259 f94b4a29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_evict_inode
* Struck through repros no longer work on HEAD.