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Fix ASSERT logic in l2arc_evict() #11205

Merged
merged 1 commit into from
Nov 16, 2020
Merged

Fix ASSERT logic in l2arc_evict() #11205

merged 1 commit into from
Nov 16, 2020

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gamanakis
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@gamanakis gamanakis commented Nov 14, 2020 •
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Motivation and Context

While trying to debug #9337 and #10286 I bumped into a panic as the ASSERT logic at
the end of l2arc_evict() should not be applied in case of cache device removal.

Description

See the commit message for more details.
Fix this by omitting the ASSERT at the end of l2arc_evict() in case of device removal.

How Has This Been Tested?

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Performance enhancement (non-breaking change which improves efficiency)
  • Code cleanup (non-breaking change which makes code smaller or more readable)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Documentation (a change to man pages or other documentation)

Checklist:

@gamanakis
Fix ASSERT logic in l2arc_evict()
d043d87 
In case of cache device removal it is possible that at the end of
l2arc_evict() we have l2ad_hand = l2ad_evict. This can lead to the
following panic in case of a debug build:

VERIFY3(dev->l2ad_hand < dev->l2ad_evict) failed (321920512 < 321920512)
Call Trace:
 dump_stack+0x66/0x90
 spl_panic+0xef/0x117 [spl]
 l2arc_remove_vdev+0x11d/0x290 [zfs]
 spa_load_l2cache+0x275/0x5b0 [zfs]
 spa_vdev_remove+0x4a5/0x6e0 [zfs]
 zfs_ioc_vdev_remove+0x59/0xa0 [zfs]
 zfsdev_ioctl_common+0x5b3/0x630 [zfs]
 zfsdev_ioctl+0x53/0xe0 [zfs]
 do_vfs_ioctl+0x42e/0x6b0
 ? __do_munmap+0x285/0x4a0
 ksys_ioctl+0x5e/0x90
 __x64_sys_ioctl+0x16/0x20
 do_syscall_64+0x5b/0x1a0
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

In case of cache device removal it also possible that l2ad_hand +
distance > l2ad_end since we do not iterate l2arc_evict() and l2ad_hand
is not reset. This has no functional consequence however as the cache
device is about to be removed.

Fix this by omitting the ASSERT in case of device removal.

Signed-off-by: George Amanakis <gamanakis@gmail.com>
@behlendorf behlendorf added the Status: Code Review Needed Ready for review and testing label Nov 15, 2020
@behlendorf behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Nov 15, 2020
@behlendorf behlendorf merged commit 2c210f6 into openzfs:master Nov 16, 2020
behlendorf pushed a commit that referenced this pull request Nov 17, 2020
@gamanakis @behlendorf
Fix ASSERT logic in l2arc_evict()
a09aeb9 
In case of cache device removal it is possible that at the end of
l2arc_evict() we have l2ad_hand = l2ad_evict. This can lead to the
following panic in case of a debug build:

VERIFY3(dev->l2ad_hand < dev->l2ad_evict) failed (321920512 < 321920512)
Call Trace:
 dump_stack+0x66/0x90
 spl_panic+0xef/0x117 [spl]
 l2arc_remove_vdev+0x11d/0x290 [zfs]
 spa_load_l2cache+0x275/0x5b0 [zfs]
 spa_vdev_remove+0x4a5/0x6e0 [zfs]
 zfs_ioc_vdev_remove+0x59/0xa0 [zfs]
 zfsdev_ioctl_common+0x5b3/0x630 [zfs]
 zfsdev_ioctl+0x53/0xe0 [zfs]
 do_vfs_ioctl+0x42e/0x6b0
 ksys_ioctl+0x5e/0x90
 do_syscall_64+0x5b/0x1a0
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

In case of cache device removal it also possible that l2ad_hand +
distance > l2ad_end since we do not iterate l2arc_evict() and l2ad_hand
is not reset. This has no functional consequence however as the cache
device is about to be removed.

Fix this by omitting the ASSERT in case of device removal.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #11205
jsai20 pushed a commit to jsai20/zfs that referenced this pull request Mar 30, 2021
@gamanakis @jsai20
Fix ASSERT logic in l2arc_evict()
2e3a5d2 
In case of cache device removal it is possible that at the end of
l2arc_evict() we have l2ad_hand = l2ad_evict. This can lead to the
following panic in case of a debug build:

VERIFY3(dev->l2ad_hand < dev->l2ad_evict) failed (321920512 < 321920512)
Call Trace:
 dump_stack+0x66/0x90
 spl_panic+0xef/0x117 [spl]
 l2arc_remove_vdev+0x11d/0x290 [zfs]
 spa_load_l2cache+0x275/0x5b0 [zfs]
 spa_vdev_remove+0x4a5/0x6e0 [zfs]
 zfs_ioc_vdev_remove+0x59/0xa0 [zfs]
 zfsdev_ioctl_common+0x5b3/0x630 [zfs]
 zfsdev_ioctl+0x53/0xe0 [zfs]
 do_vfs_ioctl+0x42e/0x6b0
 ksys_ioctl+0x5e/0x90
 do_syscall_64+0x5b/0x1a0
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

In case of cache device removal it also possible that l2ad_hand +
distance > l2ad_end since we do not iterate l2arc_evict() and l2ad_hand
is not reset. This has no functional consequence however as the cache
device is about to be removed.

Fix this by omitting the ASSERT in case of device removal.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes openzfs#11205
sempervictus pushed a commit to sempervictus/zfs that referenced this pull request May 31, 2021
@gamanakis
Fix ASSERT logic in l2arc_evict()
d0c2d33 
In case of cache device removal it is possible that at the end of
l2arc_evict() we have l2ad_hand = l2ad_evict. This can lead to the
following panic in case of a debug build:

VERIFY3(dev->l2ad_hand < dev->l2ad_evict) failed (321920512 < 321920512)
Call Trace:
 dump_stack+0x66/0x90
 spl_panic+0xef/0x117 [spl]
 l2arc_remove_vdev+0x11d/0x290 [zfs]
 spa_load_l2cache+0x275/0x5b0 [zfs]
 spa_vdev_remove+0x4a5/0x6e0 [zfs]
 zfs_ioc_vdev_remove+0x59/0xa0 [zfs]
 zfsdev_ioctl_common+0x5b3/0x630 [zfs]
 zfsdev_ioctl+0x53/0xe0 [zfs]
 do_vfs_ioctl+0x42e/0x6b0
 ksys_ioctl+0x5e/0x90
 do_syscall_64+0x5b/0x1a0
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

In case of cache device removal it also possible that l2ad_hand +
distance > l2ad_end since we do not iterate l2arc_evict() and l2ad_hand
is not reset. This has no functional consequence however as the cache
device is about to be removed.

Fix this by omitting the ASSERT in case of device removal.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes openzfs#11205
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