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d0424066fc
If we are trying to unlock the filesystem via an administrative
interface and nfsd isn't running, it crashes the server. This
happens currently because nfsd4_revoke_states() access state
structures (eg., conf_id_hashtbl) that has been freed as a part
of the server shutdown.
[ 59.465072] Call trace:
[ 59.465308] nfsd4_revoke_states+0x1b4/0x898 [nfsd] (P)
[ 59.465830] write_unlock_fs+0x258/0x440 [nfsd]
[ 59.466278] nfsctl_transaction_write+0xb0/0x120 [nfsd]
[ 59.466780] vfs_write+0x1f0/0x938
[ 59.467088] ksys_write+0xfc/0x1f8
[ 59.467395] __arm64_sys_write+0x74/0xb8
[ 59.467746] invoke_syscall.constprop.0+0xdc/0x1e8
[ 59.468177] do_el0_svc+0x154/0x1d8
[ 59.468489] el0_svc+0x40/0xe0
[ 59.468767] el0t_64_sync_handler+0xa0/0xe8
[ 59.469138] el0t_64_sync+0x1ac/0x1b0
Ensure this can't happen by taking the nfsd_mutex and checking that
the server is still up, and then holding the mutex across the call to
nfsd4_revoke_states().
Reviewed-by: NeilBrown <neil@brown.name>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Fixes: 1ac3629bf0 ("nfsd: prepare for supporting admin-revocation of state")
Cc: stable@vger.kernel.org
Signed-off-by: Olga Kornievskaia <okorniev@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.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.