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Since commitd869da91cc("nfs/blocklayout: Fix premature PR key unregistration") an unmount of a pNFS SCSI layout-enabled NFS may dereference a NULL block_device in: bl_unregister_scsi+0x16/0xe0 [blocklayoutdriver] bl_free_device+0x70/0x80 [blocklayoutdriver] bl_free_deviceid_node+0x12/0x30 [blocklayoutdriver] nfs4_put_deviceid_node+0x60/0xc0 [nfsv4] nfs4_deviceid_purge_client+0x132/0x190 [nfsv4] unset_pnfs_layoutdriver+0x59/0x60 [nfsv4] nfs4_destroy_server+0x36/0x70 [nfsv4] nfs_free_server+0x23/0xe0 [nfs] deactivate_locked_super+0x30/0xb0 cleanup_mnt+0xba/0x150 task_work_run+0x59/0x90 syscall_exit_to_user_mode+0x217/0x220 do_syscall_64+0x8e/0x160 This happens because even though we were able to create the nfs4_deviceid_node, the lookup for the device was unable to attach the block device to the pnfs_block_dev. If we never found a block device to register, we can avoid this case with the PNFS_BDEV_REGISTERED flag. Move the deref behind the test for the flag. Fixes:d869da91cc("nfs/blocklayout: Fix premature PR key unregistration") Signed-off-by: Benjamin Coddington <bcodding@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.