possible deadlock in sg_mmap

Status: auto-obsoleted due to no activity on 2025/04/18 13:35
Subsystems: scsi
[Documentation on labels]
Reported-by: syzbot+941903927d608a37e1f6@syzkaller.appspotmail.com
First crash: 592d, last: 592d
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[syzbot] Monthly scsi report (Jan 2025) 0 (1) 2025/01/16 13:07
[syzbot] [scsi?] possible deadlock in sg_mmap 0 (1) 2025/01/12 13:37

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc6-syzkaller-00038-g09a0fa92e5b4 #0 Not tainted
------------------------------------------------------
syz.4.2070/14808 is trying to acquire lock:
ffff88804d7b9730 (&vma->vm_lock->lock){++++}-{4:4}, at: vma_start_write include/linux/mm.h:770 [inline]
ffff88804d7b9730 (&vma->vm_lock->lock){++++}-{4:4}, at: vm_flags_set include/linux/mm.h:900 [inline]
ffff88804d7b9730 (&vma->vm_lock->lock){++++}-{4:4}, at: sg_mmap+0x2ea/0x530 drivers/scsi/sg.c:1288

but task is already holding lock:
ffff888078718110 (&sfp->f_mutex){+.+.}-{4:4}, at: sg_mmap+0x13b/0x530 drivers/scsi/sg.c:1273

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (&sfp->f_mutex){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
       sg_mmap+0x13b/0x530 drivers/scsi/sg.c:1273
       call_mmap include/linux/fs.h:2183 [inline]
       mmap_file mm/internal.h:124 [inline]
       __mmap_new_file_vma mm/vma.c:2291 [inline]
       __mmap_new_vma mm/vma.c:2355 [inline]
       __mmap_region+0x2250/0x2d30 mm/vma.c:2456
       mmap_region+0x1d0/0x2c0 mm/mmap.c:1352
       do_mmap+0x97a/0x10d0 mm/mmap.c:500
       vm_mmap_pgoff+0x1dd/0x3d0 mm/util.c:575
       ksys_mmap_pgoff+0x4eb/0x720 mm/mmap.c:546
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (&mm->mmap_lock){++++}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __might_fault+0xc6/0x120 mm/memory.c:6751
       _inline_copy_from_user include/linux/uaccess.h:162 [inline]
       _copy_from_user+0x2a/0xc0 lib/usercopy.c:18
       copy_from_user include/linux/uaccess.h:212 [inline]
       __blk_trace_setup kernel/trace/blktrace.c:626 [inline]
       blk_trace_ioctl+0x1ad/0x9a0 kernel/trace/blktrace.c:740
       blkdev_ioctl+0x40c/0x6a0 block/ioctl.c:682
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (&q->debugfs_mutex){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
       blk_mq_init_sched+0x3fa/0x830 block/blk-mq-sched.c:473
       elevator_init_mq+0x20e/0x320 block/elevator.c:610
       add_disk_fwnode+0x10d/0xf80 block/genhd.c:413
       sd_probe+0xba6/0x1100 drivers/scsi/sd.c:4024
       really_probe+0x2ba/0xad0 drivers/base/dd.c:658
       __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:800
       driver_probe_device+0x50/0x430 drivers/base/dd.c:830
       __device_attach_driver+0x2d6/0x530 drivers/base/dd.c:958
       bus_for_each_drv+0x250/0x2e0 drivers/base/bus.c:459
       __device_attach_async_helper+0x22d/0x300 drivers/base/dd.c:987
       async_run_entry_fn+0xaa/0x420 kernel/async.c:129
       process_one_work kernel/workqueue.c:3229 [inline]
       process_scheduled_works+0xa68/0x1840 kernel/workqueue.c:3310
       worker_thread+0x870/0xd30 kernel/workqueue.c:3391
       kthread+0x2f2/0x390 kernel/kthread.c:389
       ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #4 (&q->q_usage_counter(queue)#50){++++}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       blk_queue_enter+0xe1/0x600 block/blk-core.c:328
       blk_mq_alloc_request+0x4fa/0xaa0 block/blk-mq.c:652
       scsi_alloc_request drivers/scsi/scsi_lib.c:1222 [inline]
       scsi_execute_cmd+0x177/0x1090 drivers/scsi/scsi_lib.c:304
       read_capacity_16+0x2b4/0x1450 drivers/scsi/sd.c:2655
       sd_read_capacity drivers/scsi/sd.c:2824 [inline]
       sd_revalidate_disk+0x1013/0xbce0 drivers/scsi/sd.c:3734
       sd_probe+0x9fa/0x1100 drivers/scsi/sd.c:4010
       really_probe+0x2ba/0xad0 drivers/base/dd.c:658
       __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:800
       driver_probe_device+0x50/0x430 drivers/base/dd.c:830
       __device_attach_driver+0x2d6/0x530 drivers/base/dd.c:958
       bus_for_each_drv+0x250/0x2e0 drivers/base/bus.c:459
       __device_attach_async_helper+0x22d/0x300 drivers/base/dd.c:987
       async_run_entry_fn+0xaa/0x420 kernel/async.c:129
       process_one_work kernel/workqueue.c:3229 [inline]
       process_scheduled_works+0xa68/0x1840 kernel/workqueue.c:3310
       worker_thread+0x870/0xd30 kernel/workqueue.c:3391
       kthread+0x2f2/0x390 kernel/kthread.c:389
       ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #3 (&q->limits_lock){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
       queue_limits_start_update include/linux/blkdev.h:947 [inline]
       loop_reconfigure_limits+0x43f/0x900 drivers/block/loop.c:998
       loop_set_block_size drivers/block/loop.c:1473 [inline]
       lo_simple_ioctl drivers/block/loop.c:1496 [inline]
       lo_ioctl+0x1351/0x1f50 drivers/block/loop.c:1559
       blkdev_ioctl+0x57f/0x6a0 block/ioctl.c:693
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&q->q_usage_counter(io)#24){++++}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       bio_queue_enter block/blk.h:75 [inline]
       blk_mq_submit_bio+0x1536/0x2390 block/blk-mq.c:3090
       __submit_bio+0x2c6/0x560 block/blk-core.c:629
       __submit_bio_noacct_mq block/blk-core.c:710 [inline]
       submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:739
       mpage_bio_submit_read fs/mpage.c:75 [inline]
       mpage_readahead+0x630/0x780 fs/mpage.c:377
       read_pages+0x178/0x750 mm/readahead.c:160
       page_cache_ra_unbounded+0x606/0x720 mm/readahead.c:295
       do_page_cache_ra mm/readahead.c:325 [inline]
       force_page_cache_ra mm/readahead.c:354 [inline]
       page_cache_sync_ra+0x3c5/0xad0 mm/readahead.c:566
       page_cache_sync_readahead include/linux/pagemap.h:1397 [inline]
       filemap_get_pages+0x605/0x2080 mm/filemap.c:2537
       filemap_read+0x452/0xf50 mm/filemap.c:2637
       blkdev_read_iter+0x2d8/0x430 block/fops.c:770
       new_sync_read fs/read_write.c:484 [inline]
       vfs_read+0x993/0xb70 fs/read_write.c:565
       ksys_read+0x18f/0x2b0 fs/read_write.c:708
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (mapping.invalidate_lock#2){++++}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       down_read+0xb1/0xa40 kernel/locking/rwsem.c:1524
       filemap_invalidate_lock_shared include/linux/fs.h:873 [inline]
       filemap_fault+0x615/0x1490 mm/filemap.c:3323
       __do_fault+0x137/0x390 mm/memory.c:4907
       do_read_fault mm/memory.c:5322 [inline]
       do_fault mm/memory.c:5456 [inline]
       do_pte_missing mm/memory.c:3979 [inline]
       handle_pte_fault+0x39eb/0x5ed0 mm/memory.c:5801
       __handle_mm_fault mm/memory.c:5944 [inline]
       handle_mm_fault+0x1106/0x1bb0 mm/memory.c:6112
       do_user_addr_fault arch/x86/mm/fault.c:1338 [inline]
       handle_page_fault arch/x86/mm/fault.c:1481 [inline]
       exc_page_fault+0x459/0x8b0 arch/x86/mm/fault.c:1539
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #0 (&vma->vm_lock->lock){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       down_write+0x99/0x220 kernel/locking/rwsem.c:1577
       vma_start_write include/linux/mm.h:770 [inline]
       vm_flags_set include/linux/mm.h:900 [inline]
       sg_mmap+0x2ea/0x530 drivers/scsi/sg.c:1288
       call_mmap include/linux/fs.h:2183 [inline]
       mmap_file mm/internal.h:124 [inline]
       __mmap_new_file_vma mm/vma.c:2291 [inline]
       __mmap_new_vma mm/vma.c:2355 [inline]
       __mmap_region+0x2250/0x2d30 mm/vma.c:2456
       mmap_region+0x1d0/0x2c0 mm/mmap.c:1352
       do_mmap+0x97a/0x10d0 mm/mmap.c:500
       vm_mmap_pgoff+0x1dd/0x3d0 mm/util.c:575
       ksys_mmap_pgoff+0x4eb/0x720 mm/mmap.c:546
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &vma->vm_lock->lock --> &mm->mmap_lock --> &sfp->f_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sfp->f_mutex);
                               lock(&mm->mmap_lock);
                               lock(&sfp->f_mutex);
  lock(&vma->vm_lock->lock);

 *** DEADLOCK ***

2 locks held by syz.4.2070/14808:
 #0: ffff88807c3b0ba0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
 #0: ffff88807c3b0ba0 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x17c/0x3d0 mm/util.c:573
 #1: ffff888078718110 (&sfp->f_mutex){+.+.}-{4:4}, at: sg_mmap+0x13b/0x530 drivers/scsi/sg.c:1273

stack backtrace:
CPU: 0 UID: 0 PID: 14808 Comm: syz.4.2070 Not tainted 6.13.0-rc6-syzkaller-00038-g09a0fa92e5b4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
 check_noncircular+0x36a/0x4a0 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+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 down_write+0x99/0x220 kernel/locking/rwsem.c:1577
 vma_start_write include/linux/mm.h:770 [inline]
 vm_flags_set include/linux/mm.h:900 [inline]
 sg_mmap+0x2ea/0x530 drivers/scsi/sg.c:1288
 call_mmap include/linux/fs.h:2183 [inline]
 mmap_file mm/internal.h:124 [inline]
 __mmap_new_file_vma mm/vma.c:2291 [inline]
 __mmap_new_vma mm/vma.c:2355 [inline]
 __mmap_region+0x2250/0x2d30 mm/vma.c:2456
 mmap_region+0x1d0/0x2c0 mm/mmap.c:1352
 do_mmap+0x97a/0x10d0 mm/mmap.c:500
 vm_mmap_pgoff+0x1dd/0x3d0 mm/util.c:575
 ksys_mmap_pgoff+0x4eb/0x720 mm/mmap.c:546
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb7d3b85d29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb7d4a0c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fb7d3d76080 RCX: 00007fb7d3b85d29
RDX: 000000000100000e RSI: 0000000000003000 RDI: 0000000020000000
RBP: 00007fb7d3c01b08 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000000012 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb7d3d76080 R15: 00007ffe771b7b78
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/08 13:34 upstream 09a0fa92e5b4 f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in sg_mmap
* Struck through repros no longer work on HEAD.