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---
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---
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
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| Linux | Linux | affected |
|
No data.
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Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Mon, 02 Feb 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Sat, 31 Jan 2026 11:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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--- | |
| Title | btrfs: release path before initializing extent tree in btrfs_read_locked_inode() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-02-09T08:37:11.853Z
Reserved: 2026-01-13T15:37:45.940Z
Link: CVE-2026-23018
Vulnrichment
No data.
NVD
Status : Awaiting Analysis
Published: 2026-01-31T12:16:05.100
Modified: 2026-02-03T16:44:36.630
Link: CVE-2026-23018
Redhat
OpenCVE Enrichment
No data.
Weaknesses
No weakness.