In the Linux kernel, the following vulnerability has been resolved:
btrfs: defrag: fix deadlock between defrag and delalloc space reservation
While running fsstress with autodefrag and flushoncommit, hit a deadlock
due to the fact that defrag reserves delalloc space while it's holding
dirty and locked folios, besides the extent range lock. The stack traces
are the following:
[958.624] task:kworker/u50:3 state:D stack:0 pid:20365 tgid:20365 ppid:2 task_flags:0x4208060 flags:0x00080000
[958.626] Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs]
[958.627] Call Trace:
[958.628] <TASK>
[958.628] __schedule+0x4be/0x10f0
[958.629] ? preempt_count_add+0x69/0xa0
[958.630] schedule+0x26/0xd0
[958.631] wait_current_trans+0x102/0x160 [btrfs]
[958.632] ? __pfx_autoremove_wake_function+0x10/0x10
[958.633] start_transaction+0x374/0x900 [btrfs]
[958.634] btrfs_commit_current_transaction+0x1d/0x70 [btrfs]
[958.635] flush_space+0xca/0x5e0 [btrfs]
[958.636] ? _raw_spin_unlock+0x15/0x30
[958.637] ? btrfs_reduce_alloc_profile+0x8c/0x190 [btrfs]
[958.639] ? _raw_spin_unlock+0x15/0x30
[958.640] ? calc_available_free_space.isra.0+0x6f/0x110 [btrfs]
[958.641] do_async_reclaim_metadata_space+0x84/0x190 [btrfs]
[958.642] btrfs_async_reclaim_metadata_space+0x64/0x80 [btrfs]
[958.644] process_one_work+0x19d/0x3a0
[958.644] worker_thread+0x1c4/0x330
[958.645] ? __pfx_worker_thread+0x10/0x10
[958.646] kthread+0xfc/0x130
[958.647] ? __pfx_kthread+0x10/0x10
[958.648] ret_from_fork+0x1f7/0x2c0
[958.648] ? __pfx_kthread+0x10/0x10
[958.649] ret_from_fork_asm+0x1a/0x30
[958.650] </TASK>
[958.651] task:kworker/u49:7 state:D stack:0 pid:52990 tgid:52990 ppid:2 task_flags:0x4208060 flags:0x00080000
[958.653] Workqueue: writeback wb_workfn (flush-btrfs-334)
[958.655] Call Trace:
[958.655] <TASK>
[958.656] __schedule+0x4be/0x10f0
[958.657] ? __blk_flush_plug+0xe9/0x140
[958.658] schedule+0x26/0xd0
[958.658] io_schedule+0x42/0x70
[958.659] folio_wait_bit_common+0x12b/0x330
[958.660] ? folio_wait_bit_common+0x100/0x330
[958.662] ? __pfx_wake_page_function+0x10/0x10
[958.663] extent_write_cache_pages+0x599/0x830 [btrfs]
[958.664] ? acpi_fwnode_get_reference_args+0x1fa/0x270
[958.665] btrfs_writepages+0x77/0x130 [btrfs]
[958.666] ? __pfx_end_bbio_data_write+0x10/0x10 [btrfs]
[958.667] do_writepages+0xc6/0x160
[958.668] __writeback_single_inode+0x42/0x310
[958.669] writeback_sb_inodes+0x231/0x570
[958.670] wb_writeback+0x8a/0x340
[958.671] wb_workfn+0xbf/0x450
[958.672] ? finish_task_switch.isra.0+0xc1/0x350
[958.673] process_one_work+0x19d/0x3a0
[958.673] worker_thread+0x1c4/0x330
[958.674] ? __pfx_worker_thread+0x10/0x10
[958.675] kthread+0xfc/0x130
[958.676] ? __pfx_kthread+0x10/0x10
[958.676] ret_from_fork+0x1f7/0x2c0
[958.677] ? __pfx_kthread+0x10/0x10
[958.678] ret_from_fork_asm+0x1a/0x30
[958.679] </TASK>
[958.679] task:btrfs-cleaner state:D stack:0 pid:296750 tgid:296750 ppid:2 task_flags:0x208040 flags:0x00080000
[958.681] Call Trace:
[958.682] <TASK>
[958.682] __schedule+0x4be/0x10f0
[958.683] schedule+0x26/0xd0
[958.684] handle_reserve_ticket+0x1b9/0x2c0 [btrfs]
[958.685] ? __pfx_autoremove_wake_function+0x10/0x10
[958.686] reserve_bytes+0x283/0x4c0 [btrfs]
[958.687] btrfs_reserve_metadata_bytes+0x18/0xb0 [btrfs]
[958.688] btrfs_delalloc_reserve_metadata+0x121/0x320 [btrfs]
[958.690] btrfs_delalloc_reserve_space+0x46/0xb0 [btrfs]
[958.691] btrfs_defrag_file+0x903/0x1110 [btrfs]
[958.692] btrfs_run_defrag_inodes+0x334/0x430 [btrfs]
[958.694] cleaner_kthread+0x97/0x1c0 [btrfs]
[958.694] ? __pfx_cleaner_kthread+0x10/0x10 [btrfs]
[958.696] kthread+0xfc/0x130
[958.696] ? __pfx_kthread+0x10/0x10
[958.697] ret_
---truncated---
btrfs: defrag: fix deadlock between defrag and delalloc space reservation
While running fsstress with autodefrag and flushoncommit, hit a deadlock
due to the fact that defrag reserves delalloc space while it's holding
dirty and locked folios, besides the extent range lock. The stack traces
are the following:
[958.624] task:kworker/u50:3 state:D stack:0 pid:20365 tgid:20365 ppid:2 task_flags:0x4208060 flags:0x00080000
[958.626] Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs]
[958.627] Call Trace:
[958.628] <TASK>
[958.628] __schedule+0x4be/0x10f0
[958.629] ? preempt_count_add+0x69/0xa0
[958.630] schedule+0x26/0xd0
[958.631] wait_current_trans+0x102/0x160 [btrfs]
[958.632] ? __pfx_autoremove_wake_function+0x10/0x10
[958.633] start_transaction+0x374/0x900 [btrfs]
[958.634] btrfs_commit_current_transaction+0x1d/0x70 [btrfs]
[958.635] flush_space+0xca/0x5e0 [btrfs]
[958.636] ? _raw_spin_unlock+0x15/0x30
[958.637] ? btrfs_reduce_alloc_profile+0x8c/0x190 [btrfs]
[958.639] ? _raw_spin_unlock+0x15/0x30
[958.640] ? calc_available_free_space.isra.0+0x6f/0x110 [btrfs]
[958.641] do_async_reclaim_metadata_space+0x84/0x190 [btrfs]
[958.642] btrfs_async_reclaim_metadata_space+0x64/0x80 [btrfs]
[958.644] process_one_work+0x19d/0x3a0
[958.644] worker_thread+0x1c4/0x330
[958.645] ? __pfx_worker_thread+0x10/0x10
[958.646] kthread+0xfc/0x130
[958.647] ? __pfx_kthread+0x10/0x10
[958.648] ret_from_fork+0x1f7/0x2c0
[958.648] ? __pfx_kthread+0x10/0x10
[958.649] ret_from_fork_asm+0x1a/0x30
[958.650] </TASK>
[958.651] task:kworker/u49:7 state:D stack:0 pid:52990 tgid:52990 ppid:2 task_flags:0x4208060 flags:0x00080000
[958.653] Workqueue: writeback wb_workfn (flush-btrfs-334)
[958.655] Call Trace:
[958.655] <TASK>
[958.656] __schedule+0x4be/0x10f0
[958.657] ? __blk_flush_plug+0xe9/0x140
[958.658] schedule+0x26/0xd0
[958.658] io_schedule+0x42/0x70
[958.659] folio_wait_bit_common+0x12b/0x330
[958.660] ? folio_wait_bit_common+0x100/0x330
[958.662] ? __pfx_wake_page_function+0x10/0x10
[958.663] extent_write_cache_pages+0x599/0x830 [btrfs]
[958.664] ? acpi_fwnode_get_reference_args+0x1fa/0x270
[958.665] btrfs_writepages+0x77/0x130 [btrfs]
[958.666] ? __pfx_end_bbio_data_write+0x10/0x10 [btrfs]
[958.667] do_writepages+0xc6/0x160
[958.668] __writeback_single_inode+0x42/0x310
[958.669] writeback_sb_inodes+0x231/0x570
[958.670] wb_writeback+0x8a/0x340
[958.671] wb_workfn+0xbf/0x450
[958.672] ? finish_task_switch.isra.0+0xc1/0x350
[958.673] process_one_work+0x19d/0x3a0
[958.673] worker_thread+0x1c4/0x330
[958.674] ? __pfx_worker_thread+0x10/0x10
[958.675] kthread+0xfc/0x130
[958.676] ? __pfx_kthread+0x10/0x10
[958.676] ret_from_fork+0x1f7/0x2c0
[958.677] ? __pfx_kthread+0x10/0x10
[958.678] ret_from_fork_asm+0x1a/0x30
[958.679] </TASK>
[958.679] task:btrfs-cleaner state:D stack:0 pid:296750 tgid:296750 ppid:2 task_flags:0x208040 flags:0x00080000
[958.681] Call Trace:
[958.682] <TASK>
[958.682] __schedule+0x4be/0x10f0
[958.683] schedule+0x26/0xd0
[958.684] handle_reserve_ticket+0x1b9/0x2c0 [btrfs]
[958.685] ? __pfx_autoremove_wake_function+0x10/0x10
[958.686] reserve_bytes+0x283/0x4c0 [btrfs]
[958.687] btrfs_reserve_metadata_bytes+0x18/0xb0 [btrfs]
[958.688] btrfs_delalloc_reserve_metadata+0x121/0x320 [btrfs]
[958.690] btrfs_delalloc_reserve_space+0x46/0xb0 [btrfs]
[958.691] btrfs_defrag_file+0x903/0x1110 [btrfs]
[958.692] btrfs_run_defrag_inodes+0x334/0x430 [btrfs]
[958.694] cleaner_kthread+0x97/0x1c0 [btrfs]
[958.694] ? __pfx_cleaner_kthread+0x10/0x10 [btrfs]
[958.696] kthread+0xfc/0x130
[958.696] ? __pfx_kthread+0x10/0x10
[958.697] ret_
---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 |
|
||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data.
Advisories
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Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 17 Sep 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: btrfs: defrag: fix deadlock between defrag and delalloc space reservation While running fsstress with autodefrag and flushoncommit, hit a deadlock due to the fact that defrag reserves delalloc space while it's holding dirty and locked folios, besides the extent range lock. The stack traces are the following: [958.624] task:kworker/u50:3 state:D stack:0 pid:20365 tgid:20365 ppid:2 task_flags:0x4208060 flags:0x00080000 [958.626] Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs] [958.627] Call Trace: [958.628] <TASK> [958.628] __schedule+0x4be/0x10f0 [958.629] ? preempt_count_add+0x69/0xa0 [958.630] schedule+0x26/0xd0 [958.631] wait_current_trans+0x102/0x160 [btrfs] [958.632] ? __pfx_autoremove_wake_function+0x10/0x10 [958.633] start_transaction+0x374/0x900 [btrfs] [958.634] btrfs_commit_current_transaction+0x1d/0x70 [btrfs] [958.635] flush_space+0xca/0x5e0 [btrfs] [958.636] ? _raw_spin_unlock+0x15/0x30 [958.637] ? btrfs_reduce_alloc_profile+0x8c/0x190 [btrfs] [958.639] ? _raw_spin_unlock+0x15/0x30 [958.640] ? calc_available_free_space.isra.0+0x6f/0x110 [btrfs] [958.641] do_async_reclaim_metadata_space+0x84/0x190 [btrfs] [958.642] btrfs_async_reclaim_metadata_space+0x64/0x80 [btrfs] [958.644] process_one_work+0x19d/0x3a0 [958.644] worker_thread+0x1c4/0x330 [958.645] ? __pfx_worker_thread+0x10/0x10 [958.646] kthread+0xfc/0x130 [958.647] ? __pfx_kthread+0x10/0x10 [958.648] ret_from_fork+0x1f7/0x2c0 [958.648] ? __pfx_kthread+0x10/0x10 [958.649] ret_from_fork_asm+0x1a/0x30 [958.650] </TASK> [958.651] task:kworker/u49:7 state:D stack:0 pid:52990 tgid:52990 ppid:2 task_flags:0x4208060 flags:0x00080000 [958.653] Workqueue: writeback wb_workfn (flush-btrfs-334) [958.655] Call Trace: [958.655] <TASK> [958.656] __schedule+0x4be/0x10f0 [958.657] ? __blk_flush_plug+0xe9/0x140 [958.658] schedule+0x26/0xd0 [958.658] io_schedule+0x42/0x70 [958.659] folio_wait_bit_common+0x12b/0x330 [958.660] ? folio_wait_bit_common+0x100/0x330 [958.662] ? __pfx_wake_page_function+0x10/0x10 [958.663] extent_write_cache_pages+0x599/0x830 [btrfs] [958.664] ? acpi_fwnode_get_reference_args+0x1fa/0x270 [958.665] btrfs_writepages+0x77/0x130 [btrfs] [958.666] ? __pfx_end_bbio_data_write+0x10/0x10 [btrfs] [958.667] do_writepages+0xc6/0x160 [958.668] __writeback_single_inode+0x42/0x310 [958.669] writeback_sb_inodes+0x231/0x570 [958.670] wb_writeback+0x8a/0x340 [958.671] wb_workfn+0xbf/0x450 [958.672] ? finish_task_switch.isra.0+0xc1/0x350 [958.673] process_one_work+0x19d/0x3a0 [958.673] worker_thread+0x1c4/0x330 [958.674] ? __pfx_worker_thread+0x10/0x10 [958.675] kthread+0xfc/0x130 [958.676] ? __pfx_kthread+0x10/0x10 [958.676] ret_from_fork+0x1f7/0x2c0 [958.677] ? __pfx_kthread+0x10/0x10 [958.678] ret_from_fork_asm+0x1a/0x30 [958.679] </TASK> [958.679] task:btrfs-cleaner state:D stack:0 pid:296750 tgid:296750 ppid:2 task_flags:0x208040 flags:0x00080000 [958.681] Call Trace: [958.682] <TASK> [958.682] __schedule+0x4be/0x10f0 [958.683] schedule+0x26/0xd0 [958.684] handle_reserve_ticket+0x1b9/0x2c0 [btrfs] [958.685] ? __pfx_autoremove_wake_function+0x10/0x10 [958.686] reserve_bytes+0x283/0x4c0 [btrfs] [958.687] btrfs_reserve_metadata_bytes+0x18/0xb0 [btrfs] [958.688] btrfs_delalloc_reserve_metadata+0x121/0x320 [btrfs] [958.690] btrfs_delalloc_reserve_space+0x46/0xb0 [btrfs] [958.691] btrfs_defrag_file+0x903/0x1110 [btrfs] [958.692] btrfs_run_defrag_inodes+0x334/0x430 [btrfs] [958.694] cleaner_kthread+0x97/0x1c0 [btrfs] [958.694] ? __pfx_cleaner_kthread+0x10/0x10 [btrfs] [958.696] kthread+0xfc/0x130 [958.696] ? __pfx_kthread+0x10/0x10 [958.697] ret_ ---truncated--- | |
| Title | btrfs: defrag: fix deadlock between defrag and delalloc space reservation | |
| 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: 2026-09-17T16:08:01.372Z
Reserved: 2026-09-11T19:38:34.796Z
Link: CVE-2026-90265
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T17:17:23.017
Modified: 2026-09-17T17:17:23.017
Link: CVE-2026-90265
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.