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AJvYcCXJ0pz3oQqWfs9Amc/HnTAFv8Sx6DwpeQhwxrJElmCZlNEb+7dCjChyNiV73mKM7ZGeVIN+kxQOX61OAxE=@vger.kernel.org X-Gm-Message-State: AOJu0YyP6nMcPyyYyW9qPTUVMYK2vZ8LC4gWs8t2kETM53Q1DDUGl7oG 5aHmbP6mjnfmK4GP83k61tZPlh/8T0eoGMigS+ZJjjnu08sdjxcDQA5cD1iarBPoz5sKJijrxB5 XmXDng9PETUEAvnnkywMFzpQdIIg9W3ZeQ+RaEavvT79bs9mMgxERx3+xAfU= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1c9f:b0:664:86ce:df5a with SMTP id 006d021491bc7-66d09cb2a11mr396150eaf.10.1770327873382; Thu, 05 Feb 2026 13:44:33 -0800 (PST) Date: Thu, 05 Feb 2026 13:44:33 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69850f41.a00a0220.34fa92.001d.GAE@google.com> Subject: [syzbot] [mm?] possible deadlock in gup_fast_fallback (2) From: syzbot To: akpm@linux-foundation.org, david@kernel.org, jgg@ziepe.ca, jhubbard@nvidia.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, peterx@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: f14faaf3a1fb Merge tag 'tsm-fixes-for-6.19' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10928a52580000 kernel config: https://syzkaller.appspot.com/x/.config?x=4aae00ac5a9d2645 dashboard link: https://syzkaller.appspot.com/bug?extid=c8461425abb63bfd3445 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17078a5a580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14df4b22580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f14faaf3.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/2fe7f2219e97/vmlinux-f14faaf3.xz kernel image: https://storage.googleapis.com/syzbot-assets/b1acb6ecfb89/bzImage-f14faaf3.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/c52bcc06e784/mount_0.gz fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=13a5c7fa580000) IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c8461425abb63bfd3445@syzkaller.appspotmail.com loop0: detected capacity change from 0 to 32768 XFS (loop0): Mounting V5 Filesystem bfdc47fc-10d8-4eed-a562-11a831b3f791 XFS (loop0): Ending clean mount ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.17/5488 is trying to acquire lock: ffff888044e06540 (&mm->mmap_lock){++++}-{4:4}, at: gup_fast_fallback+0x20d/0x22e0 mm/gup.c:3204 but task is already holding lock: ffff8880467da130 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: xfs_ilock_demote+0xbd/0x290 fs/xfs/xfs_inode.c:285 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sb->s_type->i_mutex_key#24){++++}-{4:4}: down_read_nested+0x49/0x2e0 kernel/locking/rwsem.c:1662 xfs_ilock+0x109/0x360 fs/xfs/xfs_inode.c:152 xfs_ilock_iocb fs/xfs/xfs_file.c:195 [inline] xfs_file_buffered_read+0x15b/0x330 fs/xfs/xfs_file.c:284 xfs_file_read_iter+0x280/0x510 fs/xfs/xfs_file.c:312 __kernel_read+0x504/0x9b0 fs/read_write.c:530 freader_fetch+0x1cb/0xa00 lib/buildid.c:100 __build_id_parse+0x168/0x870 lib/buildid.c:297 do_procmap_query fs/proc/task_mmu.c:733 [inline] procfs_procmap_ioctl+0x7ae/0xd50 fs/proc/task_mmu.c:813 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (vm_lock){++++}-{0:0}: __vma_enter_locked+0x243/0x710 mm/mmap_lock.c:72 __vma_start_write+0x23/0x140 mm/mmap_lock.c:104 vma_start_write include/linux/mmap_lock.h:213 [inline] mprotect_fixup+0x5e1/0xa50 mm/mprotect.c:768 setup_arg_pages+0x565/0xae0 fs/exec.c:670 load_elf_binary+0xc5e/0x2980 fs/binfmt_elf.c:1028 search_binary_handler fs/exec.c:1669 [inline] exec_binprm fs/exec.c:1701 [inline] bprm_execve+0x93d/0x1410 fs/exec.c:1753 kernel_execve+0x8ef/0x9e0 fs/exec.c:1919 try_to_run_init_process+0x13/0x60 init/main.c:1506 kernel_init+0xad/0x1d0 init/main.c:1634 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 -> #0 (&mm->mmap_lock){++++}-{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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868 gup_fast_fallback+0x226/0x22e0 mm/gup.c:3204 iov_iter_extract_user_pages lib/iov_iter.c:1763 [inline] iov_iter_extract_pages+0x37b/0x5f0 lib/iov_iter.c:1826 __bio_iov_iter_get_pages block/bio.c:1237 [inline] bio_iov_iter_get_pages+0x4a8/0x14b0 block/bio.c:1359 iomap_dio_bio_iter+0xcb3/0x14d0 fs/iomap/direct-io.c:460 iomap_dio_iter fs/iomap/direct-io.c:-1 [inline] __iomap_dio_rw+0xf57/0x1e10 fs/iomap/direct-io.c:753 iomap_dio_rw+0x45/0xb0 fs/iomap/direct-io.c:847 xfs_file_dio_write_aligned+0x36a/0x450 fs/xfs/xfs_file.c:707 xfs_file_dio_write fs/xfs/xfs_file.c:910 [inline] xfs_file_write_iter+0x7dd/0x920 fs/xfs/xfs_file.c:1122 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x61d/0xb90 fs/read_write.c:686 ksys_write+0x150/0x270 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 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: &mm->mmap_lock --> vm_lock --> &sb->s_type->i_mutex_key#24 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&sb->s_type->i_mutex_key#24); lock(vm_lock); lock(&sb->s_type->i_mutex_key#24); rlock(&mm->mmap_lock); *** DEADLOCK *** 2 locks held by syz.0.17/5488: #0: ffff888031ac6420 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2683 [inline] #0: ffff888031ac6420 (sb_writers#12){.+.+}-{0:0}, at: vfs_write+0x227/0xb90 fs/read_write.c:682 #1: ffff8880467da130 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: xfs_ilock_demote+0xbd/0x290 fs/xfs/xfs_inode.c:285 stack backtrace: CPU: 0 UID: 0 PID: 5488 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868 gup_fast_fallback+0x226/0x22e0 mm/gup.c:3204 iov_iter_extract_user_pages lib/iov_iter.c:1763 [inline] iov_iter_extract_pages+0x37b/0x5f0 lib/iov_iter.c:1826 __bio_iov_iter_get_pages block/bio.c:1237 [inline] bio_iov_iter_get_pages+0x4a8/0x14b0 block/bio.c:1359 iomap_dio_bio_iter+0xcb3/0x14d0 fs/iomap/direct-io.c:460 iomap_dio_iter fs/iomap/direct-io.c:-1 [inline] __iomap_dio_rw+0xf57/0x1e10 fs/iomap/direct-io.c:753 iomap_dio_rw+0x45/0xb0 fs/iomap/direct-io.c:847 xfs_file_dio_write_aligned+0x36a/0x450 fs/xfs/xfs_file.c:707 xfs_file_dio_write fs/xfs/xfs_file.c:910 [inline] xfs_file_write_iter+0x7dd/0x920 fs/xfs/xfs_file.c:1122 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x61d/0xb90 fs/read_write.c:686 ksys_write+0x150/0x270 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f85b679aeb9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd910b1588 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f85b6a15fa0 RCX: 00007f85b679aeb9 RDX: 000000000000f000 RSI: 0000200000000200 RDI: 0000000000000007 RBP: 00007f85b6808c1f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f85b6a15fac R14: 00007f85b6a15fa0 R15: 00007f85b6a15fa0 --- 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@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup