CVE-2026-23018: In the Linux kernel, the following vulnerability has been resolved:  btrfs: release path before initializing extent tree in btrfs_read_locked_inode()  In btrfs_read_locked_inode() we are calling btrfs_init_file_extent_tree() while holding a path with a read locked leaf from a subvolume tree, and btrfs_init_file_extent_tree() may do a GFP_KERNEL allocation, which can trigger reclaim.  This can create a circular lock dependency which lockdep warns about with the following splat:     [6.1433] ======================================================    [6.1574] WARNING: possible circular locking dependency detected    [6.1583] 6.18.0+ #4 Tainted: G     U    [6.1591] ------------------------------------------------------    [6.1599] kswapd0/117 is trying to acquire lock:    [6.1606] ffff8d9b6333c5b8 (&delayed_node->mutex){+.+.}-{3:3}, at: __btrfs_release_delayed_node.part.0+0x39/0x2f0    [6.1625]             but task is already holding lock:    [6.1633] ffffffffa4ab8ce0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x195/0xc60    [6.1646]             which lock already depends on the new lock.     [6.1657]             the existing dependency chain (in reverse order) is:    [6.1667]             -> #2 (fs_reclaim){+.+.}-{0:0}:    [6.1677]        fs_reclaim_acquire+0x9d/0xd0    [6.1685]        __kmalloc_cache_noprof+0x59/0x750    [6.1694]        btrfs_init_file_extent_tree+0x90/0x100    [6.1702]        btrfs_read_locked_inode+0xc3/0x6b0    [6.1710]        btrfs_iget+0xbb/0xf0    [6.1716]        btrfs_lookup_dentry+0x3c5/0x8e0    [6.1724]        btrfs_lookup+0x12/0x30    [6.1731]        lookup_open.isra.0+0x1aa/0x6a0    [6.1739]        path_openat+0x5f7/0xc60    [6.1746]        do_filp_open+0xd6/0x180    [6.1753]        do_sys_openat2+0x8b/0xe0    [6.1760]        __x64_sys_openat+0x54/0xa0    [6.1768]        do_syscall_64+0x97/0x3e0    [6.1776]        entry_SYSCALL_64_after_hwframe+0x76/0x7e    [6.1784]             -> #1 (btrfs-tree-00){++++}-{3:3}:    [6.1794]        lock_release+0x127/0x2a0    [6.1801]        up_read+0x1b/0x30    [6.1808]        btrfs_search_slot+0x8e0/0xff0    [6.1817]        btrfs_lookup_inode+0x52/0xd0    [6.1825]        __btrfs_update_delayed_inode+0x73/0x520    [6.1833]        btrfs_commit_inode_delayed_inode+0x11a/0x120    [6.1842]        btrfs_log_inode+0x608/0x1aa0    [6.1849]        btrfs_log_inode_parent+0x249/0xf80    [6.1857]        btrfs_log_dentry_safe+0x3e/0x60    [6.1865]        btrfs_sync_file+0x431/0x690    [6.1872]        do_fsync+0x39/0x80    [6.1879]        __x64_sys_fsync+0x13/0x20    [6.1887]        do_syscall_64+0x97/0x3e0    [6.1894]        entry_SYSCALL_64_after_hwframe+0x76/0x7e    [6.1903]             -> #0 (&delayed_node->mutex){+.+.}-{3:3}:    [6.1913]        __lock_acquire+0x15e9/0x2820    [6.1920]        lock_acquire+0xc9/0x2d0    [6.1927]        __mutex_lock+0xcc/0x10a0    [6.1934]        __btrfs_release_delayed_node.part.0+0x39/0x2f0    [6.1944]        btrfs_evict_inode+0x20b/0x4b0    [6.1952]        evict+0x15a/0x2f0    [6.1958]        prune_icache_sb+0x91/0xd0    [6.1966]        super_cache_scan+0x150/0x1d0    [6.1974]        do_shrink_slab+0x155/0x6f0    [6.1981]        shrink_slab+0x48e/0x890    [6.1988]        shrink_one+0x11a/0x1f0    [6.1995]        shrink_node+0xbfd/0x1320    [6.1002]        balance_pgdat+0x67f/0xc60    [6.1321]        kswapd+0x1dc/0x3e0    [6.1643]        kthread+0xff/0x240    [6.1965]        ret_from_fork+0x223/0x280    [6.1287]        ret_from_fork_asm+0x1a/0x30    [6.1616]             other info that might help us debug this:     [6.1561] Chain exists of:               &delayed_node->mutex --> btrfs-tree-00 --> fs_reclaim     [6.1503]  Possible unsafe locking scenario:     [6.1110]        CPU0                    CPU1    [6.1411]        ----                    ----    [6.1707]   lock(fs_reclaim);    [6.1998]                                lock(btrfs-tree-00);    [6.1291]                                lock(fs_reclaim);    [6.1581]   lock(&del ---truncated---