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Message-ID: <683be4c5.a00a0220.d8eae.0028.GAE@google.com>
Date: Sat, 31 May 2025 22:27:33 -0700
From: syzbot <syzbot+9f17e6387907dc224b18@...kaller.appspotmail.com>
To: airlied@...il.com, dri-devel@...ts.freedesktop.org,
hamohammed.sa@...il.com, linux-kernel@...r.kernel.org,
louis.chauvet@...tlin.com, maarten.lankhorst@...ux.intel.com,
melissa.srw@...il.com, mripard@...nel.org, simona@...ll.ch,
syzkaller-bugs@...glegroups.com, tzimmermann@...e.de
Subject: [syzbot] [dri?] possible deadlock in drm_mode_setcrtc
Hello,
syzbot found the following issue on:
HEAD commit: d7fa1af5b33e Merge branch 'for-next/core' into for-kernelci
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=10597170580000
kernel config: https://syzkaller.appspot.com/x/.config?x=89c13de706fbf07a
dashboard link: https://syzkaller.appspot.com/bug?extid=9f17e6387907dc224b18
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
userspace arch: arm64
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/da97ad659b2c/disk-d7fa1af5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/659e123552a8/vmlinux-d7fa1af5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6ec5dbf4643e/Image-d7fa1af5.gz.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9f17e6387907dc224b18@...kaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc7-syzkaller-gd7fa1af5b33e #0 Not tainted
------------------------------------------------------
syz.0.268/7988 is trying to acquire lock:
ffff0000d5c9c5d0 (&mm->mmap_lock){++++}-{4:4}, at: __might_fault+0x9c/0x124 mm/memory.c:7150
but task is already holding lock:
ffff80009ce07948 (crtc_ww_class_mutex){+.+.}-{4:4}, at: drm_mode_setcrtc+0x3e4/0x182c drivers/gpu/drm/drm_crtc.c:730
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (crtc_ww_class_mutex){+.+.}-{4:4}:
ww_acquire_init include/linux/ww_mutex.h:162 [inline]
drm_modeset_acquire_init+0x1d8/0x374 drivers/gpu/drm/drm_modeset_lock.c:250
drmm_mode_config_init+0xb0c/0x10d8 drivers/gpu/drm/drm_mode_config.c:462
vkms_modeset_init drivers/gpu/drm/vkms/vkms_drv.c:146 [inline]
vkms_create drivers/gpu/drm/vkms/vkms_drv.c:207 [inline]
vkms_init+0x2c0/0x5ac drivers/gpu/drm/vkms/vkms_drv.c:242
do_one_initcall+0x250/0x990 init/main.c:1257
do_initcall_level+0x154/0x214 init/main.c:1319
do_initcalls+0x84/0xf4 init/main.c:1335
do_basic_setup+0x8c/0xa0 init/main.c:1354
kernel_init_freeable+0x2dc/0x444 init/main.c:1567
kernel_init+0x24/0x1dc init/main.c:1457
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
-> #6 (crtc_ww_class_acquire){+.+.}-{0:0}:
ww_acquire_init include/linux/ww_mutex.h:161 [inline]
drm_modeset_acquire_init+0x1b8/0x374 drivers/gpu/drm/drm_modeset_lock.c:250
drm_client_modeset_commit_atomic+0xcc/0x6ac drivers/gpu/drm/drm_client_modeset.c:1018
drm_client_modeset_commit_locked+0xd0/0x4a0 drivers/gpu/drm/drm_client_modeset.c:1182
drm_client_modeset_commit+0x50/0x7c drivers/gpu/drm/drm_client_modeset.c:1208
__drm_fb_helper_restore_fbdev_mode_unlocked+0x94/0x198 drivers/gpu/drm/drm_fb_helper.c:237
drm_fb_helper_set_par+0xa4/0x108 drivers/gpu/drm/drm_fb_helper.c:1359
fbcon_init+0xe4c/0x1d18 drivers/video/fbdev/core/fbcon.c:1112
visual_init+0x27c/0x540 drivers/tty/vt/vt.c:1011
do_bind_con_driver+0x7b8/0xdd8 drivers/tty/vt/vt.c:3831
do_take_over_console+0x824/0x97c drivers/tty/vt/vt.c:4397
do_fbcon_takeover+0x158/0x25c drivers/video/fbdev/core/fbcon.c:548
do_fb_registered drivers/video/fbdev/core/fbcon.c:2989 [inline]
fbcon_fb_registered+0x354/0x4c8 drivers/video/fbdev/core/fbcon.c:3009
do_register_framebuffer drivers/video/fbdev/core/fbmem.c:449 [inline]
register_framebuffer+0x44c/0x5ec drivers/video/fbdev/core/fbmem.c:515
__drm_fb_helper_initial_config_and_unlock+0x103c/0x159c drivers/gpu/drm/drm_fb_helper.c:1851
drm_fb_helper_initial_config+0x3c/0x58 drivers/gpu/drm/drm_fb_helper.c:1916
drm_fbdev_client_hotplug+0x154/0x22c drivers/gpu/drm/clients/drm_fbdev_client.c:52
drm_client_register+0x13c/0x1d4 drivers/gpu/drm/drm_client.c:140
drm_fbdev_client_setup+0x194/0x3d0 drivers/gpu/drm/clients/drm_fbdev_client.c:159
drm_client_setup+0x78/0x140 drivers/gpu/drm/clients/drm_client_setup.c:39
vkms_create drivers/gpu/drm/vkms/vkms_drv.c:218 [inline]
vkms_init+0x4b8/0x5ac drivers/gpu/drm/vkms/vkms_drv.c:242
do_one_initcall+0x250/0x990 init/main.c:1257
do_initcall_level+0x154/0x214 init/main.c:1319
do_initcalls+0x84/0xf4 init/main.c:1335
do_basic_setup+0x8c/0xa0 init/main.c:1354
kernel_init_freeable+0x2dc/0x444 init/main.c:1567
kernel_init+0x24/0x1dc init/main.c:1457
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
-> #5 (&client->modeset_mutex){+.+.}-{4:4}:
__mutex_lock_common+0x1d0/0x2190 kernel/locking/mutex.c:601
__mutex_lock kernel/locking/mutex.c:746 [inline]
mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:798
drm_client_modeset_probe+0x2f0/0x4e88 drivers/gpu/drm/drm_client_modeset.c:843
__drm_fb_helper_initial_config_and_unlock+0xf0/0x159c drivers/gpu/drm/drm_fb_helper.c:1828
drm_fb_helper_initial_config+0x3c/0x58 drivers/gpu/drm/drm_fb_helper.c:1916
drm_fbdev_client_hotplug+0x154/0x22c drivers/gpu/drm/clients/drm_fbdev_client.c:52
drm_client_register+0x13c/0x1d4 drivers/gpu/drm/drm_client.c:140
drm_fbdev_client_setup+0x194/0x3d0 drivers/gpu/drm/clients/drm_fbdev_client.c:159
drm_client_setup+0x78/0x140 drivers/gpu/drm/clients/drm_client_setup.c:39
vkms_create drivers/gpu/drm/vkms/vkms_drv.c:218 [inline]
vkms_init+0x4b8/0x5ac drivers/gpu/drm/vkms/vkms_drv.c:242
do_one_initcall+0x250/0x990 init/main.c:1257
do_initcall_level+0x154/0x214 init/main.c:1319
do_initcalls+0x84/0xf4 init/main.c:1335
do_basic_setup+0x8c/0xa0 init/main.c:1354
kernel_init_freeable+0x2dc/0x444 init/main.c:1567
kernel_init+0x24/0x1dc init/main.c:1457
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
-> #4 (&helper->lock){+.+.}-{4:4}:
__mutex_lock_common+0x1d0/0x2190 kernel/locking/mutex.c:601
__mutex_lock kernel/locking/mutex.c:746 [inline]
mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:798
__drm_fb_helper_restore_fbdev_mode_unlocked+0x74/0x198 drivers/gpu/drm/drm_fb_helper.c:228
drm_fb_helper_set_par+0xa4/0x108 drivers/gpu/drm/drm_fb_helper.c:1359
fbcon_init+0xe4c/0x1d18 drivers/video/fbdev/core/fbcon.c:1112
visual_init+0x27c/0x540 drivers/tty/vt/vt.c:1011
do_bind_con_driver+0x7b8/0xdd8 drivers/tty/vt/vt.c:3831
do_take_over_console+0x824/0x97c drivers/tty/vt/vt.c:4397
do_fbcon_takeover+0x158/0x25c drivers/video/fbdev/core/fbcon.c:548
do_fb_registered drivers/video/fbdev/core/fbcon.c:2989 [inline]
fbcon_fb_registered+0x354/0x4c8 drivers/video/fbdev/core/fbcon.c:3009
do_register_framebuffer drivers/video/fbdev/core/fbmem.c:449 [inline]
register_framebuffer+0x44c/0x5ec drivers/video/fbdev/core/fbmem.c:515
__drm_fb_helper_initial_config_and_unlock+0x103c/0x159c drivers/gpu/drm/drm_fb_helper.c:1851
drm_fb_helper_initial_config+0x3c/0x58 drivers/gpu/drm/drm_fb_helper.c:1916
drm_fbdev_client_hotplug+0x154/0x22c drivers/gpu/drm/clients/drm_fbdev_client.c:52
drm_client_register+0x13c/0x1d4 drivers/gpu/drm/drm_client.c:140
drm_fbdev_client_setup+0x194/0x3d0 drivers/gpu/drm/clients/drm_fbdev_client.c:159
drm_client_setup+0x78/0x140 drivers/gpu/drm/clients/drm_client_setup.c:39
vkms_create drivers/gpu/drm/vkms/vkms_drv.c:218 [inline]
vkms_init+0x4b8/0x5ac drivers/gpu/drm/vkms/vkms_drv.c:242
do_one_initcall+0x250/0x990 init/main.c:1257
do_initcall_level+0x154/0x214 init/main.c:1319
do_initcalls+0x84/0xf4 init/main.c:1335
do_basic_setup+0x8c/0xa0 init/main.c:1354
kernel_init_freeable+0x2dc/0x444 init/main.c:1567
kernel_init+0x24/0x1dc init/main.c:1457
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
-> #3 (console_lock){+.+.}-{0:0}:
console_lock+0x194/0x1ec kernel/printk/printk.c:2849
__bch2_print_string_as_lines fs/bcachefs/util.c:267 [inline]
bch2_print_string_as_lines+0x34/0x150 fs/bcachefs/util.c:286
bucket_ref_update_err+0x1c8/0x21c fs/bcachefs/buckets.c:417
bch2_bucket_ref_update+0x3d8/0x888 fs/bcachefs/buckets.c:-1
__mark_pointer fs/bcachefs/buckets.c:572 [inline]
bch2_trigger_pointer fs/bcachefs/buckets.c:618 [inline]
__trigger_extent+0xd90/0x35fc fs/bcachefs/buckets.c:763
bch2_trigger_extent+0x3e4/0x78c fs/bcachefs/buckets.c:881
run_one_trans_trigger fs/bcachefs/btree_trans_commit.c:-1 [inline]
bch2_trans_commit_run_triggers fs/bcachefs/btree_trans_commit.c:550 [inline]
__bch2_trans_commit+0x7e8/0x62d0 fs/bcachefs/btree_trans_commit.c:990
bch2_trans_commit fs/bcachefs/btree_update.h:195 [inline]
bch2_extent_update+0x2d8/0x7e8 fs/bcachefs/io_write.c:353
bch2_fpunch_at+0x4dc/0x98c fs/bcachefs/io_misc.c:187
__bchfs_fallocate+0xe80/0x1080 fs/bcachefs/fs-io.c:749
bchfs_fallocate+0x28c/0x538 fs/bcachefs/fs-io.c:789
bch2_fallocate_dispatch+0x344/0x4e0 fs/bcachefs/fs-io.c:836
vfs_fallocate+0x5cc/0x73c fs/open.c:338
ioctl_preallocate fs/ioctl.c:290 [inline]
file_ioctl fs/ioctl.c:-1 [inline]
do_vfs_ioctl+0x1d4c/0x2218 fs/ioctl.c:885
__do_sys_ioctl fs/ioctl.c:904 [inline]
__se_sys_ioctl fs/ioctl.c:892 [inline]
__arm64_sys_ioctl+0xe4/0x1c4 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+0x58/0x17c arch/arm64/kernel/entry-common.c:767
el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
-> #2 (bcachefs_btree){+.+.}-{0:0}:
trans_set_locked+0x94/0x200 fs/bcachefs/btree_locking.h:198
bch2_trans_begin+0x6f8/0xa40 fs/bcachefs/btree_iter.c:3288
bch2_read_err_msg_trans+0x64/0x298 fs/bcachefs/io_read.c:346
__bch2_read_extent+0x21fc/0x3694 fs/bcachefs/io_read.c:975
bch2_read_extent fs/bcachefs/io_read.h:140 [inline]
bchfs_read+0x1178/0x17dc fs/bcachefs/fs-io-buffered.c:226
bch2_read_single_folio+0x498/0x6e4 fs/bcachefs/fs-io-buffered.c:360
bch2_read_folio+0x40/0x84 fs/bcachefs/fs-io-buffered.c:378
filemap_read_folio+0xec/0x2f8 mm/filemap.c:2401
filemap_fault+0xd48/0x1278 mm/filemap.c:3495
bch2_page_fault+0x2cc/0x700 fs/bcachefs/fs-io-pagecache.c:594
__do_fault+0xf8/0x498 mm/memory.c:5098
do_shared_fault mm/memory.c:5582 [inline]
do_fault mm/memory.c:5656 [inline]
do_pte_missing mm/memory.c:4160 [inline]
handle_pte_fault mm/memory.c:5997 [inline]
__handle_mm_fault mm/memory.c:6140 [inline]
handle_mm_fault+0x1a08/0x4d18 mm/memory.c:6309
do_page_fault+0x598/0x1554 arch/arm64/mm/fault.c:690
do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:783
do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:919
el0_da+0x64/0x160 arch/arm64/kernel/entry-common.c:627
el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:789
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
-> #1 (mapping.invalidate_lock#3){.+.+}-{4:4}:
down_read+0x58/0x2f8 kernel/locking/rwsem.c:1524
filemap_invalidate_lock_shared include/linux/fs.h:922 [inline]
filemap_fault+0x564/0x1278 mm/filemap.c:3391
bch2_page_fault+0x2cc/0x700 fs/bcachefs/fs-io-pagecache.c:594
__do_fault+0xf8/0x498 mm/memory.c:5098
do_read_fault mm/memory.c:5518 [inline]
do_fault mm/memory.c:5652 [inline]
do_pte_missing mm/memory.c:4160 [inline]
handle_pte_fault mm/memory.c:5997 [inline]
__handle_mm_fault mm/memory.c:6140 [inline]
handle_mm_fault+0x2cb0/0x4d18 mm/memory.c:6309
faultin_page mm/gup.c:1193 [inline]
__get_user_pages+0x1dd4/0x30d8 mm/gup.c:1491
populate_vma_page_range+0x218/0x2e8 mm/gup.c:1929
__mm_populate+0x208/0x330 mm/gup.c:2032
mm_populate include/linux/mm.h:3487 [inline]
vm_mmap_pgoff+0x378/0x43c mm/util.c:584
ksys_mmap_pgoff+0x394/0x5b8 mm/mmap.c:607
__do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
__se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
__arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
__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+0x58/0x17c arch/arm64/kernel/entry-common.c:767
el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
-> #0 (&mm->mmap_lock){++++}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3166 [inline]
check_prevs_add kernel/locking/lockdep.c:3285 [inline]
validate_chain kernel/locking/lockdep.c:3909 [inline]
__lock_acquire+0x1728/0x3058 kernel/locking/lockdep.c:5235
lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5866
__might_fault+0xc4/0x124 mm/memory.c:7151
drm_mode_setcrtc+0xdc0/0x182c drivers/gpu/drm/drm_crtc.c:840
drm_ioctl_kernel+0x238/0x310 drivers/gpu/drm/drm_ioctl.c:796
drm_ioctl+0x65c/0xa5c 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/0x1c4 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+0x58/0x17c arch/arm64/kernel/entry-common.c:767
el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
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 ***
2 locks held by syz.0.268/7988:
#0: ffff80009ce07920 (crtc_ww_class_acquire){+.+.}-{0:0}, at: drm_mode_setcrtc+0x3e4/0x182c drivers/gpu/drm/drm_crtc.c:730
#1: ffff80009ce07948 (crtc_ww_class_mutex){+.+.}-{4:4}, at: drm_mode_setcrtc+0x3e4/0x182c drivers/gpu/drm/drm_crtc.c:730
stack backtrace:
CPU: 1 UID: 0 PID: 7988 Comm: syz.0.268 Not tainted 6.15.0-rc7-syzkaller-gd7fa1af5b33e #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
__dump_stack+0x30/0x40 lib/dump_stack.c:94
dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
dump_stack+0x1c/0x28 lib/dump_stack.c:129
print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2079
check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2211
check_prev_add kernel/locking/lockdep.c:3166 [inline]
check_prevs_add kernel/locking/lockdep.c:3285 [inline]
validate_chain kernel/locking/lockdep.c:3909 [inline]
__lock_acquire+0x1728/0x3058 kernel/locking/lockdep.c:5235
lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5866
__might_fault+0xc4/0x124 mm/memory.c:7151
drm_mode_setcrtc+0xdc0/0x182c drivers/gpu/drm/drm_crtc.c:840
drm_ioctl_kernel+0x238/0x310 drivers/gpu/drm/drm_ioctl.c:796
drm_ioctl+0x65c/0xa5c 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/0x1c4 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+0x58/0x17c arch/arm64/kernel/entry-common.c:767
el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
---
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.
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https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
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If you want to overwrite report's subsystems, reply with:
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If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
#syz undup
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