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block: fix lbmd_guard_tag_type assignment in FS_IOC_GETLBMD_CAP#42

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block: fix lbmd_guard_tag_type assignment in FS_IOC_GETLBMD_CAP#42
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series/984593=>for-next

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@blktests-ci blktests-ci Bot commented Jul 23, 2025

Pull request for series with
subject: block: fix lbmd_guard_tag_type assignment in FS_IOC_GETLBMD_CAP
version: 3
url: https://patchwork.kernel.org/project/linux-block/list/?series=984715

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blktests-ci Bot commented Jul 23, 2025

Upstream branch: a8fa173
series: https://patchwork.kernel.org/project/linux-block/list/?series=984715
version: 3

Pull request is NOT updated. Failed to apply https://patchwork.kernel.org/project/linux-block/list/?series=984715
error message:

Cmd('git') failed due to: exit code(128)
  cmdline: git am --3way
  stdout: 'Applying: block: fix lbmd_guard_tag_type assignment in FS_IOC_GETLBMD_CAP
Patch failed at 0001 block: fix lbmd_guard_tag_type assignment in FS_IOC_GETLBMD_CAP'
  stderr: 'error: sha1 information is lacking or useless (block/blk-integrity.c).
error: could not build fake ancestor
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"'

conflict:


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blktests-ci Bot commented Jul 31, 2025

Upstream branch: 4643847
series: https://patchwork.kernel.org/project/linux-block/list/?series=984715
version: 3

@blktests-ci blktests-ci Bot closed this Jul 31, 2025
@blktests-ci blktests-ci Bot force-pushed the series/984593=>for-next branch from cd1ac47 to 45d9a85 Compare July 31, 2025 04:31
@blktests-ci blktests-ci Bot deleted the series/984593=>for-next branch August 1, 2025 19:35
blktests-ci Bot pushed a commit that referenced this pull request Jan 12, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Jan 13, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Jan 14, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Jan 15, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
Reviewed-by: Jack Wang <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Jan 15, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
Reviewed-by: Jack Wang <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Jan 19, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
Reviewed-by: Jack Wang <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Jan 29, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
Reviewed-by: Jack Wang <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Feb 3, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
Reviewed-by: Jack Wang <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Feb 5, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
Reviewed-by: Jack Wang <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Feb 6, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
Reviewed-by: Jack Wang <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Feb 8, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
Reviewed-by: Jack Wang <[email protected]>
blktests-ci Bot pushed a commit that referenced this pull request Feb 9, 2026
During device unmapping (triggered by module unload or explicit unmap),
a refcount underflow occurs causing a use-after-free warning:

  [14747.574913] ------------[ cut here ]------------
  [14747.574916] refcount_t: underflow; use-after-free.
  [14747.574917] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x55/0x90, CPU#9: kworker/9:1/378
  [14747.574924] Modules linked in: rnbd_client(-) rtrs_client rnbd_server rtrs_server rtrs_core ...
  [14747.574998] CPU: 9 UID: 0 PID: 378 Comm: kworker/9:1 Tainted: G           O     N  6.19.0-rc3lblk-fnext+ #42 PREEMPT(voluntary)
  [14747.575005] Workqueue: rnbd_clt_wq unmap_device_work [rnbd_client]
  [14747.575010] RIP: 0010:refcount_warn_saturate+0x55/0x90
  [14747.575037]  Call Trace:
  [14747.575038]   <TASK>
  [14747.575038]   rnbd_clt_unmap_device+0x170/0x1d0 [rnbd_client]
  [14747.575044]   process_one_work+0x211/0x600
  [14747.575052]   worker_thread+0x184/0x330
  [14747.575055]   ? __pfx_worker_thread+0x10/0x10
  [14747.575058]   kthread+0x10d/0x250
  [14747.575062]   ? __pfx_kthread+0x10/0x10
  [14747.575066]   ret_from_fork+0x319/0x390
  [14747.575069]   ? __pfx_kthread+0x10/0x10
  [14747.575072]   ret_from_fork_asm+0x1a/0x30
  [14747.575083]   </TASK>
  [14747.575096] ---[ end trace 0000000000000000 ]---

Befor this patch :-

The bug is a double kobject_put() on dev->kobj during device cleanup.

Kobject Lifecycle:
  kobject_init_and_add()  sets kobj.kref = 1  (initialization)
  kobject_put()           sets kobj.kref = 0  (should be called once)

* Before this patch:

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs]
    kobject_put(&dev->kobj)                   PUT #1 (WRONG!)
      kref: 1 to 0
      rnbd_dev_release()
        kfree(dev)                            [DEVICE FREED!]

  rnbd_destroy_gen_disk()                     [use-after-free!]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   PUT #2 (UNDERFLOW!)
      kref: 0 to -1                           [WARNING!]

The first kobject_put() in rnbd_destroy_sysfs() prematurely frees the
device via rnbd_dev_release(), then the second kobject_put() in
rnbd_clt_put_dev() causes refcount underflow.

* After this patch :-

Remove kobject_put() from rnbd_destroy_sysfs(). This function should
only remove sysfs visibility (kobject_del), not manage object lifetime.

Call Graph (FIXED):

rnbd_clt_unmap_device()
  rnbd_destroy_sysfs()
    kobject_del(&dev->kobj)                   [remove from sysfs only]
                                              [kref unchanged: 1]

  rnbd_destroy_gen_disk()                     [device still valid]

  rnbd_clt_put_dev()
    refcount_dec_and_test(&dev->refcount)
    kobject_put(&dev->kobj)                   ONLY PUT (CORRECT!)
      kref: 1 to 0                            [BALANCED]
      rnbd_dev_release()
        kfree(dev)                            [CLEAN DESTRUCTION]

This follows the kernel pattern where sysfs removal (kobject_del) is
separate from object destruction (kobject_put).

Fixes: 581cf83 ("block: rnbd: add .release to rnbd_dev_ktype")
Signed-off-by: Chaitanya Kulkarni <[email protected]>
Acked-by: Jack Wang <[email protected]>
Reviewed-by: Jack Wang <[email protected]>
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