{"id":"CVE-2026-90265","summary":"btrfs: defrag: fix deadlock between defrag and delalloc space reservation","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: defrag: fix deadlock between defrag and delalloc space reservation\n\nWhile running fsstress with autodefrag and flushoncommit, hit a deadlock\ndue to the fact that defrag reserves delalloc space while it's holding\ndirty and locked folios, besides the extent range lock. The stack traces\nare the following:\n\n   [958.624] task:kworker/u50:3   state:D stack:0     pid:20365 tgid:20365 ppid:2      task_flags:0x4208060 flags:0x00080000\n   [958.626] Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs]\n   [958.627] Call Trace:\n   [958.628]  \u003cTASK\u003e\n   [958.628]  __schedule+0x4be/0x10f0\n   [958.629]  ? preempt_count_add+0x69/0xa0\n   [958.630]  schedule+0x26/0xd0\n   [958.631]  wait_current_trans+0x102/0x160 [btrfs]\n   [958.632]  ? __pfx_autoremove_wake_function+0x10/0x10\n   [958.633]  start_transaction+0x374/0x900 [btrfs]\n   [958.634]  btrfs_commit_current_transaction+0x1d/0x70 [btrfs]\n   [958.635]  flush_space+0xca/0x5e0 [btrfs]\n   [958.636]  ? _raw_spin_unlock+0x15/0x30\n   [958.637]  ? btrfs_reduce_alloc_profile+0x8c/0x190 [btrfs]\n   [958.639]  ? _raw_spin_unlock+0x15/0x30\n   [958.640]  ? calc_available_free_space.isra.0+0x6f/0x110 [btrfs]\n   [958.641]  do_async_reclaim_metadata_space+0x84/0x190 [btrfs]\n   [958.642]  btrfs_async_reclaim_metadata_space+0x64/0x80 [btrfs]\n   [958.644]  process_one_work+0x19d/0x3a0\n   [958.644]  worker_thread+0x1c4/0x330\n   [958.645]  ? __pfx_worker_thread+0x10/0x10\n   [958.646]  kthread+0xfc/0x130\n   [958.647]  ? __pfx_kthread+0x10/0x10\n   [958.648]  ret_from_fork+0x1f7/0x2c0\n   [958.648]  ? __pfx_kthread+0x10/0x10\n   [958.649]  ret_from_fork_asm+0x1a/0x30\n   [958.650]  \u003c/TASK\u003e\n   [958.651] task:kworker/u49:7   state:D stack:0     pid:52990 tgid:52990 ppid:2      task_flags:0x4208060 flags:0x00080000\n   [958.653] Workqueue: writeback wb_workfn (flush-btrfs-334)\n   [958.655] Call Trace:\n   [958.655]  \u003cTASK\u003e\n   [958.656]  __schedule+0x4be/0x10f0\n   [958.657]  ? __blk_flush_plug+0xe9/0x140\n   [958.658]  schedule+0x26/0xd0\n   [958.658]  io_schedule+0x42/0x70\n   [958.659]  folio_wait_bit_common+0x12b/0x330\n   [958.660]  ? folio_wait_bit_common+0x100/0x330\n   [958.662]  ? __pfx_wake_page_function+0x10/0x10\n   [958.663]  extent_write_cache_pages+0x599/0x830 [btrfs]\n   [958.664]  ? acpi_fwnode_get_reference_args+0x1fa/0x270\n   [958.665]  btrfs_writepages+0x77/0x130 [btrfs]\n   [958.666]  ? __pfx_end_bbio_data_write+0x10/0x10 [btrfs]\n   [958.667]  do_writepages+0xc6/0x160\n   [958.668]  __writeback_single_inode+0x42/0x310\n   [958.669]  writeback_sb_inodes+0x231/0x570\n   [958.670]  wb_writeback+0x8a/0x340\n   [958.671]  wb_workfn+0xbf/0x450\n   [958.672]  ? finish_task_switch.isra.0+0xc1/0x350\n   [958.673]  process_one_work+0x19d/0x3a0\n   [958.673]  worker_thread+0x1c4/0x330\n   [958.674]  ? __pfx_worker_thread+0x10/0x10\n   [958.675]  kthread+0xfc/0x130\n   [958.676]  ? __pfx_kthread+0x10/0x10\n   [958.676]  ret_from_fork+0x1f7/0x2c0\n   [958.677]  ? __pfx_kthread+0x10/0x10\n   [958.678]  ret_from_fork_asm+0x1a/0x30\n   [958.679]  \u003c/TASK\u003e\n   [958.679] task:btrfs-cleaner   state:D stack:0     pid:296750 tgid:296750 ppid:2      task_flags:0x208040 flags:0x00080000\n   [958.681] Call Trace:\n   [958.682]  \u003cTASK\u003e\n   [958.682]  __schedule+0x4be/0x10f0\n   [958.683]  schedule+0x26/0xd0\n   [958.684]  handle_reserve_ticket+0x1b9/0x2c0 [btrfs]\n   [958.685]  ? __pfx_autoremove_wake_function+0x10/0x10\n   [958.686]  reserve_bytes+0x283/0x4c0 [btrfs]\n   [958.687]  btrfs_reserve_metadata_bytes+0x18/0xb0 [btrfs]\n   [958.688]  btrfs_delalloc_reserve_metadata+0x121/0x320 [btrfs]\n   [958.690]  btrfs_delalloc_reserve_space+0x46/0xb0 [btrfs]\n   [958.691]  btrfs_defrag_file+0x903/0x1110 [btrfs]\n   [958.692]  btrfs_run_defrag_inodes+0x334/0x430 [btrfs]\n   [958.694]  cleaner_kthread+0x97/0x1c0 [btrfs]\n   [958.694]  ? __pfx_cleaner_kthread+0x10/0x10 [btrfs]\n   [958.696]  kthread+0xfc/0x130\n   [958.696]  ? __pfx_kthread+0x10/0x10\n   [958.697]  ret_\n---truncated---","modified":"2026-09-19T03:47:25.551091945Z","published":"2026-09-17T16:08:01.372Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90265.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/a9701dd06e82c345fe70debdf8835b7eb5000c59"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ac916391e1c70801649f7d6f85014f687983bc33"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ba02eab28041f9a4bbe9fc90c7249644fef6de0f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90265.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90265"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"22b398eeeed43d51e85b1008e51bf9663ac1f491"},{"fixed":"a9701dd06e82c345fe70debdf8835b7eb5000c59"},{"fixed":"ac916391e1c70801649f7d6f85014f687983bc33"},{"fixed":"ba02eab28041f9a4bbe9fc90c7249644fef6de0f"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90265.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.18.52"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90265.json"}}],"schema_version":"1.9.0"}