syzbot


possible deadlock in hugetlb_fault (2)

Status: closed as invalid on 2026/01/09 12:12
Subsystems: mm
[Documentation on labels]
First crash: 115d, last: 71d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in hugetlb_fault mm 4 2 1160d 1168d 22/29 fixed on 2023/02/24 13:50

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.6502/3711 is trying to acquire lock:
ffff8880206a2218 (&hugetlb_fault_mutex_table[i]){+.+.}-{4:4}, at: hugetlb_fault+0x302/0x2f40 mm/hugetlb.c:6699

but task is already holding lock:
ffff888025b09be0 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1679 [inline]
ffff888025b09be0 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x20/0x50 net/ipv4/tcp.c:1412

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (sk_lock-AF_INET){+.+.}-{0:0}:
       lock_sock_nested+0x41/0xf0 net/core/sock.c:3720
       lock_sock include/net/sock.h:1679 [inline]
       inet_shutdown+0x67/0x440 net/ipv4/af_inet.c:907
       nbd_mark_nsock_dead+0xae/0x5d0 drivers/block/nbd.c:319
       recv_work+0x671/0xa80 drivers/block/nbd.c:1024
       process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
       process_scheduled_works kernel/workqueue.c:3346 [inline]
       worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
       kthread+0x3c5/0x780 kernel/kthread.c:463
       ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #6 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
       nbd_handle_cmd drivers/block/nbd.c:1146 [inline]
       nbd_queue_rq+0x423/0x12d0 drivers/block/nbd.c:1210
       blk_mq_dispatch_rq_list+0x416/0x1e20 block/blk-mq.c:2129
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xcb7/0x15f0 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2367
       blk_mq_dispatch_list+0x514/0x1310 block/blk-mq.c:2928
       blk_mq_flush_plug_list block/blk-mq.c:2976 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2948
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225
       blk_finish_plug block/blk-core.c:1252 [inline]
       blk_finish_plug block/blk-core.c:1249 [inline]
       __submit_bio+0x545/0x690 block/blk-core.c:651
       __submit_bio_noacct_mq block/blk-core.c:724 [inline]
       submit_bio_noacct_nocheck+0x53d/0xc10 block/blk-core.c:755
       submit_bio_noacct+0x5bd/0x1f60 block/blk-core.c:879
       submit_bh fs/buffer.c:2829 [inline]
       block_read_full_folio+0x4db/0x850 fs/buffer.c:2461
       filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2444
       do_read_cache_folio+0x263/0x5c0 mm/filemap.c:4024
       read_mapping_folio include/linux/pagemap.h:999 [inline]
       read_part_sector+0xd4/0x370 block/partitions/core.c:722
       adfspart_check_ICS+0x93/0x940 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:141 [inline]
       blk_add_partitions block/partitions/core.c:589 [inline]
       bdev_disk_changed+0x723/0x1520 block/partitions/core.c:693
       blkdev_get_whole+0x187/0x290 block/bdev.c:748
       bdev_open+0x2c7/0xe40 block/bdev.c:957
       blkdev_open+0x34e/0x4f0 block/fops.c:701
       do_dentry_open+0x982/0x1530 fs/open.c:965
       vfs_open+0x82/0x3f0 fs/open.c:1097
       do_open fs/namei.c:3975 [inline]
       path_openat+0x1de4/0x2cb0 fs/namei.c:4134
       do_filp_open+0x20b/0x470 fs/namei.c:4161
       do_sys_openat2+0x11b/0x1d0 fs/open.c:1437
       do_sys_open fs/open.c:1452 [inline]
       __do_sys_openat fs/open.c:1468 [inline]
       __se_sys_openat fs/open.c:1463 [inline]
       __x64_sys_openat+0x174/0x210 fs/open.c:1463
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
       nbd_queue_rq+0xbd/0x12d0 drivers/block/nbd.c:1202
       blk_mq_dispatch_rq_list+0x416/0x1e20 block/blk-mq.c:2129
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xcb7/0x15f0 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2367
       blk_mq_dispatch_list+0x514/0x1310 block/blk-mq.c:2928
       blk_mq_flush_plug_list block/blk-mq.c:2976 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2948
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225
       blk_finish_plug block/blk-core.c:1252 [inline]
       blk_finish_plug block/blk-core.c:1249 [inline]
       __submit_bio+0x545/0x690 block/blk-core.c:651
       __submit_bio_noacct_mq block/blk-core.c:724 [inline]
       submit_bio_noacct_nocheck+0x53d/0xc10 block/blk-core.c:755
       submit_bio_noacct+0x5bd/0x1f60 block/blk-core.c:879
       submit_bh fs/buffer.c:2829 [inline]
       block_read_full_folio+0x4db/0x850 fs/buffer.c:2461
       filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2444
       do_read_cache_folio+0x263/0x5c0 mm/filemap.c:4024
       read_mapping_folio include/linux/pagemap.h:999 [inline]
       read_part_sector+0xd4/0x370 block/partitions/core.c:722
       adfspart_check_ICS+0x93/0x940 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:141 [inline]
       blk_add_partitions block/partitions/core.c:589 [inline]
       bdev_disk_changed+0x723/0x1520 block/partitions/core.c:693
       blkdev_get_whole+0x187/0x290 block/bdev.c:748
       bdev_open+0x2c7/0xe40 block/bdev.c:957
       blkdev_open+0x34e/0x4f0 block/fops.c:701
       do_dentry_open+0x982/0x1530 fs/open.c:965
       vfs_open+0x82/0x3f0 fs/open.c:1097
       do_open fs/namei.c:3975 [inline]
       path_openat+0x1de4/0x2cb0 fs/namei.c:4134
       do_filp_open+0x20b/0x470 fs/namei.c:4161
       do_sys_openat2+0x11b/0x1d0 fs/open.c:1437
       do_sys_open fs/open.c:1452 [inline]
       __do_sys_openat fs/open.c:1468 [inline]
       __se_sys_openat fs/open.c:1463 [inline]
       __x64_sys_openat+0x174/0x210 fs/open.c:1463
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (set->srcu){.+.+}-{0:0}:
       srcu_lock_sync include/linux/srcu.h:173 [inline]
       __synchronize_srcu+0xa1/0x290 kernel/rcu/srcutree.c:1439
       blk_mq_wait_quiesce_done block/blk-mq.c:283 [inline]
       blk_mq_wait_quiesce_done block/blk-mq.c:280 [inline]
       blk_mq_quiesce_queue block/blk-mq.c:303 [inline]
       blk_mq_quiesce_queue+0x149/0x1b0 block/blk-mq.c:298
       elevator_switch+0x17d/0x810 block/elevator.c:588
       elevator_change+0x391/0x5d0 block/elevator.c:691
       elevator_set_default+0x2e9/0x380 block/elevator.c:767
       blk_register_queue+0x384/0x4e0 block/blk-sysfs.c:942
       __add_disk+0x74a/0xf00 block/genhd.c:528
       add_disk_fwnode+0x13f/0x5d0 block/genhd.c:597
       add_disk include/linux/blkdev.h:775 [inline]
       nbd_dev_add+0x783/0xbb0 drivers/block/nbd.c:1987
       nbd_init+0x1a2/0x3c0 drivers/block/nbd.c:2702
       do_one_initcall+0x123/0x6e0 init/main.c:1283
       do_initcall_level init/main.c:1345 [inline]
       do_initcalls init/main.c:1361 [inline]
       do_basic_setup init/main.c:1380 [inline]
       kernel_init_freeable+0x5c8/0x920 init/main.c:1593
       kernel_init+0x1c/0x2b0 init/main.c:1483
       ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #3 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
       elevator_change+0x17d/0x5d0 block/elevator.c:689
       elv_iosched_store+0x315/0x3c0 block/elevator.c:824
       queue_attr_store+0x26b/0x310 block/blk-sysfs.c:869
       sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142
       kernfs_fop_write_iter+0x3af/0x570 fs/kernfs/file.c:352
       iter_file_splice_write+0xa24/0x12e0 fs/splice.c:738
       do_splice_from fs/splice.c:938 [inline]
       direct_splice_actor+0x192/0x6c0 fs/splice.c:1161
       splice_direct_to_actor+0x345/0xa30 fs/splice.c:1105
       do_splice_direct_actor fs/splice.c:1204 [inline]
       do_splice_direct+0x174/0x240 fs/splice.c:1230
       do_sendfile+0xb06/0xe50 fs/read_write.c:1370
       __do_sys_sendfile64 fs/read_write.c:1431 [inline]
       __se_sys_sendfile64 fs/read_write.c:1417 [inline]
       __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1417
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&q->q_usage_counter(io)#66){++++}-{0:0}:
       blk_alloc_queue+0x619/0x760 block/blk-core.c:461
       blk_mq_alloc_queue+0x172/0x280 block/blk-mq.c:4399
       __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4446
       null_add_dev+0xf2d/0x1eb0 drivers/block/null_blk/main.c:1999
       null_create_dev drivers/block/null_blk/main.c:2097 [inline]
       null_init+0x2c9/0x610 drivers/block/null_blk/main.c:2169
       do_one_initcall+0x123/0x6e0 init/main.c:1283
       do_initcall_level init/main.c:1345 [inline]
       do_initcalls init/main.c:1361 [inline]
       do_basic_setup init/main.c:1380 [inline]
       kernel_init_freeable+0x5c8/0x920 init/main.c:1593
       kernel_init+0x1c/0x2b0 init/main.c:1483
       ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #1 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:4269 [inline]
       fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:4283
       might_alloc include/linux/sched/mm.h:318 [inline]
       prepare_alloc_pages+0x162/0x610 mm/page_alloc.c:4951
       __alloc_frozen_pages_noprof+0x18b/0x2470 mm/page_alloc.c:5172
       alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
       alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
       alloc_pages_noprof+0x131/0x390 mm/mempolicy.c:2507
       pagetable_alloc_noprof include/linux/mm.h:2980 [inline]
       pmd_alloc_one_noprof include/asm-generic/pgalloc.h:142 [inline]
       __pmd_alloc+0x3b/0x8b0 mm/memory.c:6573
       pmd_alloc include/linux/mm.h:2937 [inline]
       huge_pte_alloc+0x41d/0x5b0 mm/hugetlb.c:7683
       hugetlb_fault+0x373/0x2f40 mm/hugetlb.c:6707
       handle_mm_fault+0xbfa/0xd10 mm/memory.c:6485
       faultin_page mm/gup.c:1126 [inline]
       __get_user_pages+0x54e/0x3530 mm/gup.c:1428
       populate_vma_page_range+0x267/0x3f0 mm/gup.c:1860
       __mm_populate+0x1d8/0x380 mm/gup.c:1963
       mm_populate include/linux/mm.h:3471 [inline]
       vm_mmap_pgoff+0x37f/0x470 mm/util.c:586
       ksys_mmap_pgoff+0x1c8/0x5c0 mm/mmap.c:604
       __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
       __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
       __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&hugetlb_fault_mutex_table[i]){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
       hugetlb_fault+0x302/0x2f40 mm/hugetlb.c:6699
       handle_mm_fault+0xbfa/0xd10 mm/memory.c:6485
       do_user_addr_fault+0x7a6/0x1370 arch/x86/mm/fault.c:1387
       handle_page_fault arch/x86/mm/fault.c:1476 [inline]
       exc_page_fault+0x64/0xc0 arch/x86/mm/fault.c:1532
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
       rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:68
       copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
       raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline]
       copy_from_user_iter lib/iov_iter.c:55 [inline]
       iterate_ubuf include/linux/iov_iter.h:30 [inline]
       iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
       iterate_and_advance include/linux/iov_iter.h:330 [inline]
       __copy_from_iter lib/iov_iter.c:249 [inline]
       _copy_from_iter+0x383/0x1720 lib/iov_iter.c:260
       copy_from_iter include/linux/uio.h:228 [inline]
       copy_from_iter_full include/linux/uio.h:245 [inline]
       skb_do_copy_data_nocache include/net/sock.h:2269 [inline]
       skb_copy_to_page_nocache include/net/sock.h:2295 [inline]
       tcp_sendmsg_locked+0x2900/0x42e0 net/ipv4/tcp.c:1272
       tcp_sendmsg+0x2e/0x50 net/ipv4/tcp.c:1413
       inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:853
       sock_sendmsg_nosec net/socket.c:727 [inline]
       __sock_sendmsg net/socket.c:742 [inline]
       ____sys_sendmsg+0x973/0xc70 net/socket.c:2630
       ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
       __sys_sendmmsg+0x200/0x420 net/socket.c:2773
       __do_sys_sendmmsg net/socket.c:2800 [inline]
       __se_sys_sendmmsg net/socket.c:2797 [inline]
       __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2797
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &hugetlb_fault_mutex_table[i] --> &nsock->tx_lock --> sk_lock-AF_INET

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_INET);
                               lock(&nsock->tx_lock);
                               lock(sk_lock-AF_INET);
  lock(&hugetlb_fault_mutex_table[i]);

 *** DEADLOCK ***

2 locks held by syz.4.6502/3711:
 #0: ffff888025b09be0 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1679 [inline]
 #0: ffff888025b09be0 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x20/0x50 net/ipv4/tcp.c:1412
 #1: ffff888079c937a0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:387 [inline]
 #1: ffff888079c937a0 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:368 [inline]
 #1: ffff888079c937a0 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x35/0x6e0 mm/mmap_lock.c:428

stack backtrace:
CPU: 0 UID: 0 PID: 3711 Comm: syz.4.6502 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2043
 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:598 [inline]
 __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
 hugetlb_fault+0x302/0x2f40 mm/hugetlb.c:6699
 handle_mm_fault+0xbfa/0xd10 mm/memory.c:6485
 do_user_addr_fault+0x7a6/0x1370 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x64/0xc0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0010:rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:74
Code: 3c 04 00 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 db 83 f9 08 73 e8 eb c5 <f3> a4 c3 cc cc cc cc 48 8b 06 48 89 07 48 8d 47 08 48 83 e0 f8 48
RSP: 0018:ffffc900043ef670 EFLAGS: 00050206
RAX: 0000000000000001 RBX: 00000000000000c4 RCX: 00000000000000c4
RDX: ffffed100f855019 RSI: 0000000000000000 RDI: ffff88807c2a8000
RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed100f855018
R10: ffff88807c2a80c3 R11: 0000000000000000 R12: ffffc900043efd50
R13: 00000000000000c4 R14: ffff88807c2a8000 R15: 00007ffffffff000
 copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline]
 copy_from_user_iter lib/iov_iter.c:55 [inline]
 iterate_ubuf include/linux/iov_iter.h:30 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
 iterate_and_advance include/linux/iov_iter.h:330 [inline]
 __copy_from_iter lib/iov_iter.c:249 [inline]
 _copy_from_iter+0x383/0x1720 lib/iov_iter.c:260
 copy_from_iter include/linux/uio.h:228 [inline]
 copy_from_iter_full include/linux/uio.h:245 [inline]
 skb_do_copy_data_nocache include/net/sock.h:2269 [inline]
 skb_copy_to_page_nocache include/net/sock.h:2295 [inline]
 tcp_sendmsg_locked+0x2900/0x42e0 net/ipv4/tcp.c:1272
 tcp_sendmsg+0x2e/0x50 net/ipv4/tcp.c:1413
 inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:853
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0x973/0xc70 net/socket.c:2630
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
 __sys_sendmmsg+0x200/0x420 net/socket.c:2773
 __do_sys_sendmmsg net/socket.c:2800 [inline]
 __se_sys_sendmmsg net/socket.c:2797 [inline]
 __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2797
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2acf78f6c9
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:00007f2ad0543038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f2acf9e5fa0 RCX: 00007f2acf78f6c9
RDX: 0000000000000003 RSI: 0000200000000080 RDI: 0000000000000003
RBP: 00007f2acf811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2acf9e6038 R14: 00007f2acf9e5fa0 R15: 00007ffd63b201a8
 </TASK>
----------------
Code disassembly (best guess):
   0:	3c 04                	cmp    $0x4,%al
   2:	00 66 66             	add    %ah,0x66(%rsi)
   5:	2e 0f 1f 84 00 00 00 	cs nopl 0x0(%rax,%rax,1)
   c:	00 00
   e:	66 90                	xchg   %ax,%ax
  10:	48 8b 06             	mov    (%rsi),%rax
  13:	48 89 07             	mov    %rax,(%rdi)
  16:	48 83 c6 08          	add    $0x8,%rsi
  1a:	48 83 c7 08          	add    $0x8,%rdi
  1e:	83 e9 08             	sub    $0x8,%ecx
  21:	74 db                	je     0xfffffffe
  23:	83 f9 08             	cmp    $0x8,%ecx
  26:	73 e8                	jae    0x10
  28:	eb c5                	jmp    0xffffffef
* 2a:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction
  2c:	c3                   	ret
  2d:	cc                   	int3
  2e:	cc                   	int3
  2f:	cc                   	int3
  30:	cc                   	int3
  31:	48 8b 06             	mov    (%rsi),%rax
  34:	48 89 07             	mov    %rax,(%rdi)
  37:	48 8d 47 08          	lea    0x8(%rdi),%rax
  3b:	48 83 e0 f8          	and    $0xfffffffffffffff8,%rax
  3f:	48                   	rex.W

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/06 01:45 upstream dc77806cf3b4 a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto possible deadlock in hugetlb_fault
2025/10/11 21:34 upstream 0739473694c4 ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto possible deadlock in hugetlb_fault
2025/09/22 16:57 upstream 07e27ad16399 770ff59f .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto possible deadlock in hugetlb_fault
* Struck through repros no longer work on HEAD.