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Sometimes unmounting an NFS filesystem mounted with pNFS SCSI
layouts triggers the following warning:
BUG: scheduling while atomic: umount.nfs4/...
__schedule_bug+0xbd/0x100
schedule_debug.constprop.0+0x19f/0x220
__schedule+0x10d/0x10a0
schedule+0x74/0x190
schedule_timeout+0xf5/0x220
io_schedule_timeout+0xd5/0x160
__wait_for_common+0x186/0x4b0
blk_execute_rq+0x2ef/0x3a0
scsi_execute_cmd+0x1ff/0x700
sd_pr_out_command.isra.0+0x242/0x380 [sd_mod]
bl_unregister_scsi.constprop.0+0x109/0x3c0 [blocklayoutdriver]
bl_unregister_dev+0x175/0x1c0 [blocklayoutdriver]
bl_free_device+0x1f/0x1b0 [blocklayoutdriver]
bl_free_deviceid_node+0x12/0x30 [blocklayoutdriver]
nfs4_put_deviceid_node+0x171/0x360 [nfsv4]
ext_tree_remove+0x11c/0x1d0 [blocklayoutdriver]
_pnfs_return_layout+0x416/0x900 [nfsv4]
nfs4_evict_inode+0x108/0x130 [nfsv4]
evict+0x316/0x750
dispose_list+0xf1/0x1a0
evict_inodes+0x33f/0x440
generic_shutdown_super+0xc9/0x4e0
kill_anon_super+0x3a/0x90
nfs_kill_super+0x44/0x60 [nfs]
deactivate_locked_super+0xb8/0x1b0
cleanup_mnt+0x25a/0x380
task_work_run+0x13e/0x210
exit_to_user_mode_loop+0x169/0x400
do_syscall_64+0x467/0x1550
entry_SYSCALL_64_after_hwframe+0x76/0x7e
The warning occurs because the block layout driver unregisters the SCSI
device while the inode lock is still held. Device unregistration issues
a SCSI PR command, which may sleep, resulting in a "scheduling while
atomic" warning.
During layout return, ext_tree_remove() invokes the layout driver's
return_range callback while holding the inode lock. For block layouts,
this callback eventually calls bl_unregister_scsi(), which may block in
scsi_execute_cmd() while issuing PR commands to the device.
Fix this by deferring the return_range callbacks until after the inode
lock has been released. The layout header reference count is incremented
before invoking return_range(), ensuring that the layout header remains
valid while the layout driver removes extents from the extent tree.
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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