possible deadlock in drm_modeset_lock (2)

Status: auto-obsoleted due to no activity on 2025/03/31 19:38
Subsystems: dri
[Documentation on labels]
Reported-by: syzbot+ec91cca93789b0a7f324@syzkaller.appspotmail.com
First crash: 594d, last: 594d
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [dri?] possible deadlock in drm_modeset_lock (2) 0 (1) 2024/12/25 19:43
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in drm_modeset_lock dri 4 1 764d 760d 0/29 auto-obsoleted due to no activity on 2024/10/13 17:46
upstream possible deadlock in drm_modeset_lock (3) dri 4 1 449d 445d 0/29 auto-obsoleted due to no activity on 2025/08/23 21:19

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc3-syzkaller-g573067a5a685 #0 Not tainted
------------------------------------------------------
syz.4.258/8224 is trying to acquire lock:
ffff0000cda21250 (&mm->mmap_lock){++++}-{4:4}, at: __might_fault+0x9c/0x124 mm/memory.c:6750

but task is already holding lock:
ffff0000c97d4518 (crtc_ww_class_mutex){+.+.}-{4:4}, at: drm_modeset_lock+0x78/0xa4 drivers/gpu/drm/drm_modeset_lock.c:398

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #8 (crtc_ww_class_mutex){+.+.}-{4:4}:
       ww_acquire_init include/linux/ww_mutex.h:162 [inline]
       drm_modeset_acquire_init+0x1e4/0x384 drivers/gpu/drm/drm_modeset_lock.c:250
       drmm_mode_config_init+0xb98/0x130c drivers/gpu/drm/drm_mode_config.c:453
       vkms_modeset_init drivers/gpu/drm/vkms/vkms_drv.c:158 [inline]
       vkms_create drivers/gpu/drm/vkms/vkms_drv.c:219 [inline]
       vkms_init+0x2fc/0x600 drivers/gpu/drm/vkms/vkms_drv.c:256
       do_one_initcall+0x254/0x9f8 init/main.c:1266
       do_initcall_level+0x154/0x214 init/main.c:1328
       do_initcalls+0x58/0xac init/main.c:1344
       do_basic_setup+0x8c/0xa0 init/main.c:1363
       kernel_init_freeable+0x324/0x478 init/main.c:1577
       kernel_init+0x24/0x2a0 init/main.c:1466
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862

-> #7 (crtc_ww_class_acquire){+.+.}-{0:0}:
       ww_acquire_init include/linux/ww_mutex.h:161 [inline]
       drm_modeset_acquire_init+0x1c4/0x384 drivers/gpu/drm/drm_modeset_lock.c:250
       drm_client_modeset_commit_atomic+0xd8/0x724 drivers/gpu/drm/drm_client_modeset.c:1009
       drm_client_modeset_commit_locked+0xd0/0x4a8 drivers/gpu/drm/drm_client_modeset.c:1173
       drm_client_modeset_commit+0x50/0x7c drivers/gpu/drm/drm_client_modeset.c:1199
       __drm_fb_helper_restore_fbdev_mode_unlocked+0xd4/0x178 drivers/gpu/drm/drm_fb_helper.c:237
       drm_fb_helper_set_par+0xc4/0x110 drivers/gpu/drm/drm_fb_helper.c:1351
       fbcon_init+0xf34/0x1eb8 drivers/video/fbdev/core/fbcon.c:1113
       visual_init+0x27c/0x548 drivers/tty/vt/vt.c:1011
       do_bind_con_driver+0x7dc/0xe04 drivers/tty/vt/vt.c:3833
       do_take_over_console+0x4ac/0x5f0 drivers/tty/vt/vt.c:4399
       do_fbcon_takeover+0x158/0x260 drivers/video/fbdev/core/fbcon.c:549
       do_fb_registered drivers/video/fbdev/core/fbcon.c:2988 [inline]
       fbcon_fb_registered+0x370/0x4ec drivers/video/fbdev/core/fbcon.c:3008
       do_register_framebuffer drivers/video/fbdev/core/fbmem.c:449 [inline]
       register_framebuffer+0x470/0x610 drivers/video/fbdev/core/fbmem.c:515
       __drm_fb_helper_initial_config_and_unlock+0x137c/0x1910 drivers/gpu/drm/drm_fb_helper.c:1841
       drm_fb_helper_initial_config+0x48/0x64 drivers/gpu/drm/drm_fb_helper.c:1906
       drm_fbdev_client_hotplug+0x158/0x22c drivers/gpu/drm/drm_fbdev_client.c:51
       drm_client_register+0x144/0x1e0 drivers/gpu/drm/drm_client.c:140
       drm_fbdev_client_setup+0x1a4/0x39c drivers/gpu/drm/drm_fbdev_client.c:158
       drm_client_setup+0x28/0x9c drivers/gpu/drm/drm_client_setup.c:29
       vkms_create drivers/gpu/drm/vkms/vkms_drv.c:230 [inline]
       vkms_init+0x4f0/0x600 drivers/gpu/drm/vkms/vkms_drv.c:256
       do_one_initcall+0x254/0x9f8 init/main.c:1266
       do_initcall_level+0x154/0x214 init/main.c:1328
       do_initcalls+0x58/0xac init/main.c:1344
       do_basic_setup+0x8c/0xa0 init/main.c:1363
       kernel_init_freeable+0x324/0x478 init/main.c:1577
       kernel_init+0x24/0x2a0 init/main.c:1466
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862

-> #6 (&client->modeset_mutex){+.+.}-{4:4}:
       __mutex_lock_common+0x218/0x28f4 kernel/locking/mutex.c:585
       __mutex_lock kernel/locking/mutex.c:735 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:787
       drm_client_modeset_probe+0x304/0x3f64 drivers/gpu/drm/drm_client_modeset.c:834
       __drm_fb_helper_initial_config_and_unlock+0x104/0x1910 drivers/gpu/drm/drm_fb_helper.c:1818
       drm_fb_helper_initial_config+0x48/0x64 drivers/gpu/drm/drm_fb_helper.c:1906
       drm_fbdev_client_hotplug+0x158/0x22c drivers/gpu/drm/drm_fbdev_client.c:51
       drm_client_register+0x144/0x1e0 drivers/gpu/drm/drm_client.c:140
       drm_fbdev_client_setup+0x1a4/0x39c drivers/gpu/drm/drm_fbdev_client.c:158
       drm_client_setup+0x28/0x9c drivers/gpu/drm/drm_client_setup.c:29
       vkms_create drivers/gpu/drm/vkms/vkms_drv.c:230 [inline]
       vkms_init+0x4f0/0x600 drivers/gpu/drm/vkms/vkms_drv.c:256
       do_one_initcall+0x254/0x9f8 init/main.c:1266
       do_initcall_level+0x154/0x214 init/main.c:1328
       do_initcalls+0x58/0xac init/main.c:1344
       do_basic_setup+0x8c/0xa0 init/main.c:1363
       kernel_init_freeable+0x324/0x478 init/main.c:1577
       kernel_init+0x24/0x2a0 init/main.c:1466
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862

-> #5 (&helper->lock){+.+.}-{4:4}:
       __mutex_lock_common+0x218/0x28f4 kernel/locking/mutex.c:585
       __mutex_lock kernel/locking/mutex.c:735 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:787
       __drm_fb_helper_restore_fbdev_mode_unlocked+0xb4/0x178 drivers/gpu/drm/drm_fb_helper.c:228
       drm_fb_helper_set_par+0xc4/0x110 drivers/gpu/drm/drm_fb_helper.c:1351
       fbcon_init+0xf34/0x1eb8 drivers/video/fbdev/core/fbcon.c:1113
       visual_init+0x27c/0x548 drivers/tty/vt/vt.c:1011
       do_bind_con_driver+0x7dc/0xe04 drivers/tty/vt/vt.c:3833
       do_take_over_console+0x4ac/0x5f0 drivers/tty/vt/vt.c:4399
       do_fbcon_takeover+0x158/0x260 drivers/video/fbdev/core/fbcon.c:549
       do_fb_registered drivers/video/fbdev/core/fbcon.c:2988 [inline]
       fbcon_fb_registered+0x370/0x4ec drivers/video/fbdev/core/fbcon.c:3008
       do_register_framebuffer drivers/video/fbdev/core/fbmem.c:449 [inline]
       register_framebuffer+0x470/0x610 drivers/video/fbdev/core/fbmem.c:515
       __drm_fb_helper_initial_config_and_unlock+0x137c/0x1910 drivers/gpu/drm/drm_fb_helper.c:1841
       drm_fb_helper_initial_config+0x48/0x64 drivers/gpu/drm/drm_fb_helper.c:1906
       drm_fbdev_client_hotplug+0x158/0x22c drivers/gpu/drm/drm_fbdev_client.c:51
       drm_client_register+0x144/0x1e0 drivers/gpu/drm/drm_client.c:140
       drm_fbdev_client_setup+0x1a4/0x39c drivers/gpu/drm/drm_fbdev_client.c:158
       drm_client_setup+0x28/0x9c drivers/gpu/drm/drm_client_setup.c:29
       vkms_create drivers/gpu/drm/vkms/vkms_drv.c:230 [inline]
       vkms_init+0x4f0/0x600 drivers/gpu/drm/vkms/vkms_drv.c:256
       do_one_initcall+0x254/0x9f8 init/main.c:1266
       do_initcall_level+0x154/0x214 init/main.c:1328
       do_initcalls+0x58/0xac init/main.c:1344
       do_basic_setup+0x8c/0xa0 init/main.c:1363
       kernel_init_freeable+0x324/0x478 init/main.c:1577
       kernel_init+0x24/0x2a0 init/main.c:1466
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862

-> #4 (console_lock){+.+.}-{0:0}:
       console_lock+0x19c/0x1f4 kernel/printk/printk.c:2833
       __bch2_print_string_as_lines fs/bcachefs/util.c:267 [inline]
       bch2_print_string_as_lines+0x2c/0xd4 fs/bcachefs/util.c:286
       __bch2_fsck_err+0x1864/0x2544 fs/bcachefs/error.c:411
       bch2_check_fix_ptr fs/bcachefs/buckets.c:112 [inline]
       bch2_check_fix_ptrs+0x15b8/0x515c fs/bcachefs/buckets.c:266
       bch2_trigger_extent+0x71c/0x814 fs/bcachefs/buckets.c:856
       bch2_key_trigger fs/bcachefs/bkey_methods.h:87 [inline]
       bch2_gc_mark_key+0x4b4/0xb70 fs/bcachefs/btree_gc.c:634
       bch2_gc_btree fs/bcachefs/btree_gc.c:670 [inline]
       bch2_gc_btrees fs/bcachefs/btree_gc.c:729 [inline]
       bch2_check_allocations+0x1018/0x48f4 fs/bcachefs/btree_gc.c:1133
       bch2_run_recovery_pass+0xe4/0x1d4 fs/bcachefs/recovery_passes.c:191
       bch2_run_recovery_passes+0x30c/0x73c fs/bcachefs/recovery_passes.c:244
       bch2_fs_recovery+0x32d8/0x55dc fs/bcachefs/recovery.c:861
       bch2_fs_start+0x30c/0x53c fs/bcachefs/super.c:1037
       bch2_fs_get_tree+0x938/0x1030 fs/bcachefs/fs.c:2170
       vfs_get_tree+0x90/0x28c fs/super.c:1814
       do_new_mount+0x278/0x900 fs/namespace.c:3507
       path_mount+0x590/0xe04 fs/namespace.c:3834
       do_mount fs/namespace.c:3847 [inline]
       __do_sys_mount fs/namespace.c:4057 [inline]
       __se_sys_mount fs/namespace.c:4034 [inline]
       __arm64_sys_mount+0x4d4/0x5ac fs/namespace.c:4034
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

-> #3 (&c->fsck_error_msgs_lock){+.+.}-{4:4}:
       __mutex_lock_common+0x218/0x28f4 kernel/locking/mutex.c:585
       __mutex_lock kernel/locking/mutex.c:735 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:787
       __bch2_fsck_err+0x344/0x2544 fs/bcachefs/error.c:282
       bch2_check_fix_ptr fs/bcachefs/buckets.c:112 [inline]
       bch2_check_fix_ptrs+0x15b8/0x515c fs/bcachefs/buckets.c:266
       bch2_trigger_extent+0x71c/0x814 fs/bcachefs/buckets.c:856
       bch2_key_trigger fs/bcachefs/bkey_methods.h:87 [inline]
       bch2_gc_mark_key+0x4b4/0xb70 fs/bcachefs/btree_gc.c:634
       bch2_gc_btree fs/bcachefs/btree_gc.c:670 [inline]
       bch2_gc_btrees fs/bcachefs/btree_gc.c:729 [inline]
       bch2_check_allocations+0x1018/0x48f4 fs/bcachefs/btree_gc.c:1133
       bch2_run_recovery_pass+0xe4/0x1d4 fs/bcachefs/recovery_passes.c:191
       bch2_run_recovery_passes+0x30c/0x73c fs/bcachefs/recovery_passes.c:244
       bch2_fs_recovery+0x32d8/0x55dc fs/bcachefs/recovery.c:861
       bch2_fs_start+0x30c/0x53c fs/bcachefs/super.c:1037
       bch2_fs_get_tree+0x938/0x1030 fs/bcachefs/fs.c:2170
       vfs_get_tree+0x90/0x28c fs/super.c:1814
       do_new_mount+0x278/0x900 fs/namespace.c:3507
       path_mount+0x590/0xe04 fs/namespace.c:3834
       do_mount fs/namespace.c:3847 [inline]
       __do_sys_mount fs/namespace.c:4057 [inline]
       __se_sys_mount fs/namespace.c:4034 [inline]
       __arm64_sys_mount+0x4d4/0x5ac fs/namespace.c:4034
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

-> #2 (&c->mark_lock){++++}-{0:0}:
       percpu_down_read+0x5c/0x2e8 include/linux/percpu-rwsem.h:51
       __bch2_disk_reservation_add+0xc4/0x9f4 fs/bcachefs/buckets.c:1170
       bch2_disk_reservation_add+0x29c/0x4f4 fs/bcachefs/buckets.h:367
       __bch2_folio_reservation_get+0x2dc/0x798 fs/bcachefs/fs-io-pagecache.c:428
       bch2_folio_reservation_get fs/bcachefs/fs-io-pagecache.c:477 [inline]
       bch2_page_mkwrite+0xa70/0xe44 fs/bcachefs/fs-io-pagecache.c:637
       do_page_mkwrite+0x140/0x2dc mm/memory.c:3176
       do_shared_fault mm/memory.c:5398 [inline]
       do_fault mm/memory.c:5460 [inline]
       do_pte_missing mm/memory.c:3979 [inline]
       handle_pte_fault+0x1418/0x5890 mm/memory.c:5801
       __handle_mm_fault mm/memory.c:5944 [inline]
       handle_mm_fault+0xf0c/0x17b0 mm/memory.c:6112
       do_page_fault+0x570/0x10a8 arch/arm64/mm/fault.c:690
       do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:783
       do_mem_abort+0x74/0x200 arch/arm64/mm/fault.c:919
       el0_da+0x60/0x178 arch/arm64/kernel/entry-common.c:604
       el0t_64_sync_handler+0xcc/0x108 arch/arm64/kernel/entry-common.c:765
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

-> #1 (sb_pagefaults#2){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1725 [inline]
       sb_start_pagefault include/linux/fs.h:1890 [inline]
       bch2_page_mkwrite+0x280/0xe44 fs/bcachefs/fs-io-pagecache.c:614
       do_page_mkwrite+0x140/0x2dc mm/memory.c:3176
       do_shared_fault mm/memory.c:5398 [inline]
       do_fault mm/memory.c:5460 [inline]
       do_pte_missing mm/memory.c:3979 [inline]
       handle_pte_fault+0x1418/0x5890 mm/memory.c:5801
       __handle_mm_fault mm/memory.c:5944 [inline]
       handle_mm_fault+0xf0c/0x17b0 mm/memory.c:6112
       do_page_fault+0x570/0x10a8 arch/arm64/mm/fault.c:690
       do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:783
       do_mem_abort+0x74/0x200 arch/arm64/mm/fault.c:919
       el0_da+0x60/0x178 arch/arm64/kernel/entry-common.c:604
       el0t_64_sync_handler+0xcc/0x108 arch/arm64/kernel/entry-common.c:765
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

-> #0 (&mm->mmap_lock){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x34f0/0x7904 kernel/locking/lockdep.c:5226
       lock_acquire+0x23c/0x724 kernel/locking/lockdep.c:5849
       __might_fault+0xc4/0x124 mm/memory.c:6751
       drm_mode_object_get_properties+0x208/0x540 drivers/gpu/drm/drm_mode_object.c:407
       drm_mode_getconnector+0xdbc/0x1214 drivers/gpu/drm/drm_connector.c:3272
       drm_ioctl_kernel+0x26c/0x368 drivers/gpu/drm/drm_ioctl.c:796
       drm_ioctl+0x624/0xb14 drivers/gpu/drm/drm_ioctl.c:893
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __arm64_sys_ioctl+0x14c/0x1cc fs/ioctl.c:892
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

other info that might help us debug this:

Chain exists of:
  &mm->mmap_lock --> crtc_ww_class_acquire --> crtc_ww_class_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(crtc_ww_class_mutex);
                               lock(crtc_ww_class_acquire);
                               lock(crtc_ww_class_mutex);
  rlock(&mm->mmap_lock);

 *** DEADLOCK ***

1 lock held by syz.4.258/8224:
 #0: ffff0000c97d4518 (crtc_ww_class_mutex){+.+.}-{4:4}, at: drm_modeset_lock+0x78/0xa4 drivers/gpu/drm/drm_modeset_lock.c:398

stack backtrace:
CPU: 0 UID: 0 PID: 8224 Comm: syz.4.258 Not tainted 6.13.0-rc3-syzkaller-g573067a5a685 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_circular_bug+0x154/0x1c0 kernel/locking/lockdep.c:2074
 check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x34f0/0x7904 kernel/locking/lockdep.c:5226
 lock_acquire+0x23c/0x724 kernel/locking/lockdep.c:5849
 __might_fault+0xc4/0x124 mm/memory.c:6751
 drm_mode_object_get_properties+0x208/0x540 drivers/gpu/drm/drm_mode_object.c:407
 drm_mode_getconnector+0xdbc/0x1214 drivers/gpu/drm/drm_connector.c:3272
 drm_ioctl_kernel+0x26c/0x368 drivers/gpu/drm/drm_ioctl.c:796
 drm_ioctl+0x624/0xb14 drivers/gpu/drm/drm_ioctl.c:893
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __arm64_sys_ioctl+0x14c/0x1cc fs/ioctl.c:892
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/21 19:37 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 573067a5a685 d7f584ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in drm_modeset_lock
* Struck through repros no longer work on HEAD.