mirror_zfs/include
Andriy Tkachuk f8457fbdc4
Fix deadlock on dmu_tx_assign() from vdev_rebuild()
vdev_rebuild() is always called with spa_config_lock held in
RW_WRITER mode. However, when it tries to call dmu_tx_assign()
the latter may hang on dmu_tx_wait() waiting for available txg.
But that available txg may not happen because txg_sync takes
spa_config_lock in order to process the current txg. So we have
a deadlock case here:

 - dmu_tx_assign() waits for txg holding spa_config_lock;
 - txg_sync waits for spa_config_lock not progressing with txg.

Here are the stacks:

    __schedule+0x24e/0x590
    schedule+0x69/0x110
    cv_wait_common+0xf8/0x130 [spl]
    __cv_wait+0x15/0x20 [spl]
    dmu_tx_wait+0x8e/0x1e0 [zfs]
    dmu_tx_assign+0x49/0x80 [zfs]
    vdev_rebuild_initiate+0x39/0xc0 [zfs]
    vdev_rebuild+0x84/0x90 [zfs]
    spa_vdev_attach+0x305/0x680 [zfs]
    zfs_ioc_vdev_attach+0xc7/0xe0 [zfs]

    cv_wait_common+0xf8/0x130 [spl]
    __cv_wait+0x15/0x20 [spl]
    spa_config_enter+0xf9/0x120 [zfs]
    spa_sync+0x6d/0x5b0 [zfs]
    txg_sync_thread+0x266/0x2f0 [zfs]

The solution is to pass txg returned by spa_vdev_enter(spa)
at the top of spa_vdev_attach() to vdev_rebuild() and call
dmu_tx_create_assigned(txg) which doesn't wait for txg.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Akash B <akash-b@hpe.com>
Reviewed-by: Alek Pinchuk <apinchuk@axcient.com>
Signed-off-by: Andriy Tkachuk <andriy.tkachuk@seagate.com>
Closes #18210
Closes #18258
2026-02-26 11:18:02 -08:00
..
os simd: detect and surface support for Intel SHA512 extensions 2026-02-25 12:47:48 -08:00
sys Fix deadlock on dmu_tx_assign() from vdev_rebuild() 2026-02-26 11:18:02 -08:00
.gitignore OpenZFS restructuring - move platform specific sources 2019-09-06 11:26:26 -07:00
cityhash.h SPDX: license tags: MIT 2025-03-13 17:56:54 -07:00
libnvpair.h SPDX: license tags: CDDL-1.0 2025-03-13 17:56:27 -07:00
libzdb.h libzdb: Initial breakout of libzdb 2024-02-05 10:00:41 -08:00
libzfs_core.h SPDX: license tags: CDDL-1.0 2025-03-13 17:56:27 -07:00
libzfs.h libshare: fold into libzfs and reorg headers a little 2025-12-19 19:52:33 -08:00
libzfsbootenv.h SPDX: license tags: CDDL-1.0 2025-03-13 17:56:27 -07:00
libzpool.h zfs_context: move vn_dumpdir to libzpool 2025-11-12 10:01:28 -08:00
libzutil.h libzutil: move NN_NUMBUF_SZ from zfs_context.h nearer to nicenum() 2025-11-12 10:02:29 -08:00
Makefile.am build: add SPDX license tags to build system files 2026-01-08 15:08:03 -08:00
zfeature_common.h Implement physical rewrites 2025-08-06 10:36:56 -07:00
zfs_comutil.h SPDX: license tags: CDDL-1.0 2025-03-13 17:56:27 -07:00
zfs_crrd.h Add TXG timestamp database 2025-08-06 10:31:21 -07:00
zfs_deleg.h ZFS allow send:encrypted 2025-09-12 09:53:31 -07:00
zfs_fletcher.h SPDX: license tags: CDDL-1.0 2025-03-13 17:56:27 -07:00
zfs_namecheck.h SPDX: license tags: CDDL-1.0 2025-03-13 17:56:27 -07:00
zfs_prop.h SPDX: license tags: CDDL-1.0 2025-03-13 17:56:27 -07:00
zfs_valstr.h events: include zio type in IO error reports 2025-05-30 10:29:29 -04:00