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0837e49ab3
rcu_dereference_key() and user_key_payload() are currently being used in
two different, incompatible ways:
(1) As a wrapper to rcu_dereference() - when only the RCU read lock used
to protect the key.
(2) As a wrapper to rcu_dereference_protected() - when the key semaphor is
used to protect the key and the may be being modified.
Fix this by splitting both of the key wrappers to produce:
(1) RCU accessors for keys when caller has the key semaphore locked:
dereference_key_locked()
user_key_payload_locked()
(2) RCU accessors for keys when caller holds the RCU read lock:
dereference_key_rcu()
user_key_payload_rcu()
This should fix following warning in the NFS idmapper
===============================
[ INFO: suspicious RCU usage. ]
4.10.0 #1 Tainted: G W
-------------------------------
./include/keys/user-type.h:53 suspicious rcu_dereference_protected() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 0
1 lock held by mount.nfs/5987:
#0: (rcu_read_lock){......}, at: [<d000000002527abc>] nfs_idmap_get_key+0x15c/0x420 [nfsv4]
stack backtrace:
CPU: 1 PID: 5987 Comm: mount.nfs Tainted: G W 4.10.0 #1
Call Trace:
dump_stack+0xe8/0x154 (unreliable)
lockdep_rcu_suspicious+0x140/0x190
nfs_idmap_get_key+0x380/0x420 [nfsv4]
nfs_map_name_to_uid+0x2a0/0x3b0 [nfsv4]
decode_getfattr_attrs+0xfac/0x16b0 [nfsv4]
decode_getfattr_generic.constprop.106+0xbc/0x150 [nfsv4]
nfs4_xdr_dec_lookup_root+0xac/0xb0 [nfsv4]
rpcauth_unwrap_resp+0xe8/0x140 [sunrpc]
call_decode+0x29c/0x910 [sunrpc]
__rpc_execute+0x140/0x8f0 [sunrpc]
rpc_run_task+0x170/0x200 [sunrpc]
nfs4_call_sync_sequence+0x68/0xa0 [nfsv4]
_nfs4_lookup_root.isra.44+0xd0/0xf0 [nfsv4]
nfs4_lookup_root+0xe0/0x350 [nfsv4]
nfs4_lookup_root_sec+0x70/0xa0 [nfsv4]
nfs4_find_root_sec+0xc4/0x100 [nfsv4]
nfs4_proc_get_rootfh+0x5c/0xf0 [nfsv4]
nfs4_get_rootfh+0x6c/0x190 [nfsv4]
nfs4_server_common_setup+0xc4/0x260 [nfsv4]
nfs4_create_server+0x278/0x3c0 [nfsv4]
nfs4_remote_mount+0x50/0xb0 [nfsv4]
mount_fs+0x74/0x210
vfs_kern_mount+0x78/0x220
nfs_do_root_mount+0xb0/0x140 [nfsv4]
nfs4_try_mount+0x60/0x100 [nfsv4]
nfs_fs_mount+0x5ec/0xda0 [nfs]
mount_fs+0x74/0x210
vfs_kern_mount+0x78/0x220
do_mount+0x254/0xf70
SyS_mount+0x94/0x100
system_call+0x38/0xe0
Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
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|---|---|---|
| .. | ||
| blocklayout | ||
| filelayout | ||
| flexfilelayout | ||
| objlayout | ||
| cache_lib.c | ||
| cache_lib.h | ||
| callback_proc.c | ||
| callback_xdr.c | ||
| callback.c | ||
| callback.h | ||
| client.c | ||
| delegation.c | ||
| delegation.h | ||
| dir.c | ||
| direct.c | ||
| dns_resolve.c | ||
| dns_resolve.h | ||
| file.c | ||
| fscache-index.c | ||
| fscache.c | ||
| fscache.h | ||
| getroot.c | ||
| inode.c | ||
| internal.h | ||
| io.c | ||
| iostat.h | ||
| Kconfig | ||
| Makefile | ||
| mount_clnt.c | ||
| namespace.c | ||
| netns.h | ||
| nfs2super.c | ||
| nfs2xdr.c | ||
| nfs3_fs.h | ||
| nfs3acl.c | ||
| nfs3client.c | ||
| nfs3proc.c | ||
| nfs3super.c | ||
| nfs3xdr.c | ||
| nfs4_fs.h | ||
| nfs4client.c | ||
| nfs4file.c | ||
| nfs4getroot.c | ||
| nfs4idmap.c | ||
| nfs4idmap.h | ||
| nfs4namespace.c | ||
| nfs4proc.c | ||
| nfs4renewd.c | ||
| nfs4session.c | ||
| nfs4session.h | ||
| nfs4state.c | ||
| nfs4super.c | ||
| nfs4sysctl.c | ||
| nfs4trace.c | ||
| nfs4trace.h | ||
| nfs4xdr.c | ||
| nfs42.h | ||
| nfs42proc.c | ||
| nfs42xdr.c | ||
| nfs.h | ||
| nfsroot.c | ||
| nfstrace.c | ||
| nfstrace.h | ||
| pagelist.c | ||
| pnfs_dev.c | ||
| pnfs_nfs.c | ||
| pnfs.c | ||
| pnfs.h | ||
| proc.c | ||
| read.c | ||
| super.c | ||
| symlink.c | ||
| sysctl.c | ||
| unlink.c | ||
| write.c | ||