syzbot


possible deadlock in sys_mbind (2)

Status: upstream: reported on 2025/03/31 17:25
Reported-by: syzbot+aa904f7ac77f89c17a57@syzkaller.appspotmail.com
First crash: 70d, last: 70d
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in sys_mbind 7 305d 321d 0/3 auto-obsoleted due to no activity on 2024/11/16 19:34
linux-6.1 possible deadlock in sys_mbind 1 309d 309d 0/3 auto-obsoleted due to no activity on 2024/11/13 14:21
linux-5.15 possible deadlock in sys_mbind (2) 2 23d 98d 0/3 upstream: reported on 2025/03/04 10:10

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.1.132-syzkaller #0 Not tainted
------------------------------------------------------
syz.4.472/6454 is trying to acquire lock:
ffff0000f63c7090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: do_mbind mm/mempolicy.c:1302 [inline]
ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: kernel_mbind mm/mempolicy.c:1481 [inline]
ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_mbind mm/mempolicy.c:1558 [inline]
ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_mbind mm/mempolicy.c:1554 [inline]
ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: __arm64_sys_mbind+0x5f4/0xb40 mm/mempolicy.c:1554

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_lock){++++}-{3:3}:
       __might_fault+0xc4/0x124 mm/memory.c:5853
       reiserfs_ioctl+0x10c/0x454 fs/reiserfs/ioctl.c:96
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl fs/ioctl.c:856 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

-> #0 (&sbi->lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049
       lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662
       __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
       __mutex_lock kernel/locking/mutex.c:747 [inline]
       mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
       reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
       map_block_for_writepage fs/reiserfs/inode.c:2388 [inline]
       reiserfs_write_full_page fs/reiserfs/inode.c:2585 [inline]
       reiserfs_writepage+0x7b0/0x2d40 fs/reiserfs/inode.c:2737
       writeout mm/migrate.c:888 [inline]
       fallback_migrate_folio mm/migrate.c:912 [inline]
       move_to_new_folio+0x624/0xc24 mm/migrate.c:961
       __migrate_folio_move mm/migrate.c:1199 [inline]
       migrate_folio_move mm/migrate.c:1297 [inline]
       migrate_pages_batch mm/migrate.c:1639 [inline]
       migrate_pages+0x29f4/0x452c mm/migrate.c:1843
       do_mbind mm/mempolicy.c:1334 [inline]
       kernel_mbind mm/mempolicy.c:1481 [inline]
       __do_sys_mbind mm/mempolicy.c:1558 [inline]
       __se_sys_mbind mm/mempolicy.c:1554 [inline]
       __arm64_sys_mbind+0x8fc/0xb40 mm/mempolicy.c:1554
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mm->mmap_lock);
                               lock(&sbi->lock);
                               lock(&mm->mmap_lock);
  lock(&sbi->lock);

 *** DEADLOCK ***

1 lock held by syz.4.472/6454:
 #0: ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
 #0: ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: do_mbind mm/mempolicy.c:1302 [inline]
 #0: ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: kernel_mbind mm/mempolicy.c:1481 [inline]
 #0: ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_mbind mm/mempolicy.c:1558 [inline]
 #0: ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_mbind mm/mempolicy.c:1554 [inline]
 #0: ffff0000d5c89f48 (&mm->mmap_lock){++++}-{3:3}, at: __arm64_sys_mbind+0x5f4/0xb40 mm/mempolicy.c:1554

stack backtrace:
CPU: 0 PID: 6454 Comm: syz.4.472 Not tainted 6.1.132-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2048
 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049
 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662
 __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
 reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
 map_block_for_writepage fs/reiserfs/inode.c:2388 [inline]
 reiserfs_write_full_page fs/reiserfs/inode.c:2585 [inline]
 reiserfs_writepage+0x7b0/0x2d40 fs/reiserfs/inode.c:2737
 writeout mm/migrate.c:888 [inline]
 fallback_migrate_folio mm/migrate.c:912 [inline]
 move_to_new_folio+0x624/0xc24 mm/migrate.c:961
 __migrate_folio_move mm/migrate.c:1199 [inline]
 migrate_folio_move mm/migrate.c:1297 [inline]
 migrate_pages_batch mm/migrate.c:1639 [inline]
 migrate_pages+0x29f4/0x452c mm/migrate.c:1843
 do_mbind mm/mempolicy.c:1334 [inline]
 kernel_mbind mm/mempolicy.c:1481 [inline]
 __do_sys_mbind mm/mempolicy.c:1558 [inline]
 __se_sys_mbind mm/mempolicy.c:1554 [inline]
 __arm64_sys_mbind+0x8fc/0xb40 mm/mempolicy.c:1554
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
REISERFS warning: green-16003 errcatch_is_left_mergeable: Invalid item type observed, run fsck ASAP
REISERFS warning: green-16003 errcatch_is_left_mergeable: Invalid item type observed, run fsck ASAP
REISERFS warning: green-16003 errcatch_is_left_mergeable: Invalid item type observed, run fsck ASAP
REISERFS warning (device loop4): vs-13060 reiserfs_update_sd_size: stat data of object [1 2 0x0 UNKNOWN] (nlink == 1) not found (pos 2)
REISERFS warning (device loop4): vs-13060 reiserfs_update_sd_size: stat data of object [1 2 0x0 UNKNOWN] (nlink == 1) not found (pos 2)
REISERFS warning: green-16003 errcatch_is_left_mergeable: Invalid item type observed, run fsck ASAP

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/31 17:24 linux-6.1.y 8e60a714ba3b d3999433 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in sys_mbind
* Struck through repros no longer work on HEAD.