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SjnH+xxffhRoZsTVx2/s8i2UmDSLsLFE6qKid7/SsHSGD8qEAqTgeGv58DNPX76FBWizqt+H/HizbAHTIpViLHzzoJHQI4QEuR7557TAB0Ntu0XiMbERf5scLucovh2VDSrGTqxf65tm5UPbMn3RqXikbRALdz4DpDSxzWAb9ru6cA5F1rvWBUnCbBYFG28yWCDYkNFR0tWB+2XOrS2bT7iH6UI50tRYeEb5FaItLXrOJqwMpIlS0QDVUCdK7sZdtajbWm3eDm+ZQdOiQstdYYA4wqw6yVMd X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: #syz fix: procfs: avoid fetching build ID while holding VMA lock On 2/5/26 1:44 PM, syzbot wrote: > 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 thanks, -- John Hubbard