syzbot

 sign-in | mailing list | source | docs
🐞 Open [696]
🐞 Fixed [72]
🐞 Invalid [869]
⬇ Missing Backports [109]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

possible deadlock in ext4_evict_inode

Status: auto-obsoleted due to no activity on 2023/07/30 00:10
Reported-by: syzbot+416315211db87d24c8f8@syzkaller.appspotmail.com
First crash: 784d, last: 781d
▶ ▼ Similar bugs (7)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ext4_evict_inode (2) ext4 18 796d 972d 0/28 auto-obsoleted due to no activity on 2023/07/14 13:24
linux-6.1 possible deadlock in ext4_evict_inode (3) 1 412d 412d 0/3 auto-obsoleted due to no activity on 2024/07/12 10:45
linux-5.15 possible deadlock in ext4_evict_inode (2) 2 434d 439d 0/3 auto-obsoleted due to no activity on 2024/06/20 13:51
upstream possible deadlock in ext4_evict_inode (3) ext4 5 266d 460d 0/28 auto-obsoleted due to no activity on 2024/12/05 07:55
upstream possible deadlock in ext4_evict_inode ext4 syz error error 38 2409d 2448d 15/28 fixed on 2020/05/22 17:31
linux-6.1 possible deadlock in ext4_evict_inode 2 679d 788d 0/3 auto-obsoleted due to no activity on 2023/10/19 10:40
linux-6.1 possible deadlock in ext4_evict_inode (2) 1 531d 531d 0/3 auto-obsoleted due to no activity on 2024/03/15 02:58

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.15.105-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.1/8677 is trying to acquire lock:
ffff88814b588650
 (sb_internal
){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1742 [inline]
){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:1859 [inline]
){.+.+}-{0:0}, at: ext4_evict_inode+0x375/0x1100 fs/ext4/inode.c:243

but task is already holding lock:
ffff88814b58abd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x314/0x12f0 fs/ext4/migrate.c:438

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+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       percpu_down_read+0x46/0x1b0 include/linux/percpu-rwsem.h:51
       ext4_writepages+0x1f6/0x3d10 fs/ext4/inode.c:2687
       do_writepages+0x481/0x730 mm/page-writeback.c:2364
       filemap_fdatawrite_wbc+0x1d6/0x230 mm/filemap.c:400
       __filemap_fdatawrite_range mm/filemap.c:433 [inline]
       filemap_write_and_wait_range+0x19e/0x280 mm/filemap.c:704
       __iomap_dio_rw+0x897/0x1f40 fs/iomap/direct-io.c:557
       iomap_dio_rw+0x38/0x80 fs/iomap/direct-io.c:672
       ext4_dio_read_iter fs/ext4/file.c:77 [inline]
       ext4_file_read_iter+0x530/0x6c0 fs/ext4/file.c:128
       call_read_iter include/linux/fs.h:2097 [inline]
       generic_file_splice_read+0x4ad/0x790 fs/splice.c:311
       do_splice_to fs/splice.c:796 [inline]
       splice_direct_to_actor+0x448/0xc10 fs/splice.c:870
       do_splice_direct+0x285/0x3d0 fs/splice.c:979
       do_sendfile+0x625/0xff0 fs/read_write.c:1249
       __do_sys_sendfile64 fs/read_write.c:1317 [inline]
       __se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1303
       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+0x61/0xcb

-> #2 (&sb->s_type->i_mutex_key#9){++++}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       down_read+0x3b/0x50 kernel/locking/rwsem.c:1488
       inode_lock_shared include/linux/fs.h:797 [inline]
       ext4_bmap+0x4b/0x410 fs/ext4/inode.c:3159
       bmap+0xa1/0xd0 fs/inode.c:1714
       jbd2_journal_bmap fs/jbd2/journal.c:978 [inline]
       __jbd2_journal_erase fs/jbd2/journal.c:1786 [inline]
       jbd2_journal_flush+0x7a2/0xc90 fs/jbd2/journal.c:2492
       ext4_ioctl_checkpoint fs/ext4/ioctl.c:848 [inline]
       __ext4_ioctl fs/ext4/ioctl.c:1266 [inline]
       ext4_ioctl+0x32c7/0x5b70 fs/ext4/ioctl.c:1278
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
       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+0x61/0xcb

-> #1 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       mutex_lock_io_nested+0x45/0x60 kernel/locking/mutex.c:777
       __jbd2_log_wait_for_space+0x213/0x760 fs/jbd2/checkpoint.c:110
       add_transaction_credits+0x950/0xc00 fs/jbd2/transaction.c:303
       start_this_handle+0x747/0x1590 fs/jbd2/transaction.c:427
       jbd2__journal_start+0x2d1/0x5c0 fs/jbd2/transaction.c:525
       __ext4_journal_start_sb+0x175/0x370 fs/ext4/ext4_jbd2.c:105
       __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
       ext4_evict_inode+0x7dd/0x1100 fs/ext4/inode.c:254
       evict+0x2a4/0x620 fs/inode.c:587
       d_delete_notify include/linux/fsnotify.h:248 [inline]
       vfs_rmdir+0x33c/0x460 fs/namei.c:4091
       do_rmdir+0x362/0x670 fs/namei.c:4139
       __do_sys_unlinkat fs/namei.c:4319 [inline]
       __se_sys_unlinkat fs/namei.c:4313 [inline]
       __x64_sys_unlinkat+0xdc/0xf0 fs/namei.c:4313
       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+0x61/0xcb

-> #0 (sb_internal){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       percpu_down_read+0x46/0x1b0 include/linux/percpu-rwsem.h:51
       __sb_start_write include/linux/fs.h:1742 [inline]
       sb_start_intwrite include/linux/fs.h:1859 [inline]
       ext4_evict_inode+0x375/0x1100 fs/ext4/inode.c:243
       evict+0x2a4/0x620 fs/inode.c:587
       ext4_ext_migrate+0x100b/0x12f0 fs/ext4/migrate.c:588
       ext4_ioctl_setflags fs/ext4/ioctl.c:455 [inline]
       ext4_fileattr_set+0xf80/0x17d0 fs/ext4/ioctl.c:763
       vfs_fileattr_set+0x8f3/0xd30 fs/ioctl.c:700
       ioctl_setflags fs/ioctl.c:732 [inline]
       do_vfs_ioctl+0x1d85/0x2b70 fs/ioctl.c:843
       __do_sys_ioctl fs/ioctl.c:872 [inline]
       __se_sys_ioctl+0x81/0x160 fs/ioctl.c:860
       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+0x61/0xcb

other info that might help us debug this:

Chain exists of:
  sb_internal --> &sb->s_type->i_mutex_key#9 --> &sbi->s_writepages_rwsem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sbi->s_writepages_rwsem);
                               lock(&sb->s_type->i_mutex_key#9);
                               lock(&sbi->s_writepages_rwsem);
  lock(sb_internal);

 *** DEADLOCK ***

3 locks held by syz-executor.1/8677:
 #0: ffff88814b588460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:421
 #1: ffff8880913335c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #1: ffff8880913335c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: vfs_fileattr_set+0x135/0xd30 fs/ioctl.c:685
 #2: ffff88814b58abd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x314/0x12f0 fs/ext4/migrate.c:438

stack backtrace:
CPU: 1 PID: 8677 Comm: syz-executor.1 Not tainted 5.15.105-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
 percpu_down_read+0x46/0x1b0 include/linux/percpu-rwsem.h:51
 __sb_start_write include/linux/fs.h:1742 [inline]
 sb_start_intwrite include/linux/fs.h:1859 [inline]
 ext4_evict_inode+0x375/0x1100 fs/ext4/inode.c:243
 evict+0x2a4/0x620 fs/inode.c:587
 ext4_ext_migrate+0x100b/0x12f0 fs/ext4/migrate.c:588
 ext4_ioctl_setflags fs/ext4/ioctl.c:455 [inline]
 ext4_fileattr_set+0xf80/0x17d0 fs/ext4/ioctl.c:763
 vfs_fileattr_set+0x8f3/0xd30 fs/ioctl.c:700
 ioctl_setflags fs/ioctl.c:732 [inline]
 do_vfs_ioctl+0x1d85/0x2b70 fs/ioctl.c:843
 __do_sys_ioctl fs/ioctl.c:872 [inline]
 __se_sys_ioctl+0x81/0x160 fs/ioctl.c:860
 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+0x61/0xcb
RIP: 0033:0x7f9b9aea10f9
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:00007f9b99413168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9b9afc0f80 RCX: 00007f9b9aea10f9
RDX: 00000000200000c0 RSI: 0000000040086602 RDI: 0000000000000004
RBP: 00007f9b9aefcb39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc2e96a44f R14: 00007f9b99413300 R15: 0000000000022000
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/04/01 00:10 linux-5.15.y c957cbb87315 f325deb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ext4_evict_inode
2023/03/28 01:31 linux-5.15.y 115472395b0a 47f3aaf1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in ext4_evict_inode
* Struck through repros no longer work on HEAD.