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authorAlexander Sverdlin <alexander.sverdlin@nokia.com>2021-12-07 17:00:39 +0300
committerJ. Bruce Fields <bfields@redhat.com>2021-12-10 19:54:59 +0300
commitb10252c7ae9c9d7c90552f88b544a44ee773af64 (patch)
treeeb69e5e677f47ae4e1af278ad871508935fe1e7b /fs
parent0fcfb00b28c0b7884635dacf38e46d60bf3d4eb1 (diff)
downloadlinux-b10252c7ae9c9d7c90552f88b544a44ee773af64.tar.xz
nfsd: Fix nsfd startup race (again)
Commit bd5ae9288d64 ("nfsd: register pernet ops last, unregister first") has re-opened rpc_pipefs_event() race against nfsd_net_id registration (register_pernet_subsys()) which has been fixed by commit bb7ffbf29e76 ("nfsd: fix nsfd startup race triggering BUG_ON"). Restore the order of register_pernet_subsys() vs register_cld_notifier(). Add WARN_ON() to prevent a future regression. Crash info: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000012 CPU: 8 PID: 345 Comm: mount Not tainted 5.4.144-... #1 pc : rpc_pipefs_event+0x54/0x120 [nfsd] lr : rpc_pipefs_event+0x48/0x120 [nfsd] Call trace: rpc_pipefs_event+0x54/0x120 [nfsd] blocking_notifier_call_chain rpc_fill_super get_tree_keyed rpc_fs_get_tree vfs_get_tree do_mount ksys_mount __arm64_sys_mount el0_svc_handler el0_svc Fixes: bd5ae9288d64 ("nfsd: register pernet ops last, unregister first") Cc: stable@vger.kernel.org Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/nfsd/nfs4recover.c1
-rw-r--r--fs/nfsd/nfsctl.c14
2 files changed, 8 insertions, 7 deletions
diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 6fedc49726bf..c634483d85d2 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -2156,6 +2156,7 @@ static struct notifier_block nfsd4_cld_block = {
int
register_cld_notifier(void)
{
+ WARN_ON(!nfsd_net_id);
return rpc_pipefs_notifier_register(&nfsd4_cld_block);
}
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index af8531c3854a..51a49e0cfe37 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1521,12 +1521,9 @@ static int __init init_nfsd(void)
int retval;
printk(KERN_INFO "Installing knfsd (copyright (C) 1996 okir@monad.swb.de).\n");
- retval = register_cld_notifier();
- if (retval)
- return retval;
retval = nfsd4_init_slabs();
if (retval)
- goto out_unregister_notifier;
+ return retval;
retval = nfsd4_init_pnfs();
if (retval)
goto out_free_slabs;
@@ -1545,9 +1542,14 @@ static int __init init_nfsd(void)
goto out_free_exports;
retval = register_pernet_subsys(&nfsd_net_ops);
if (retval < 0)
+ goto out_free_filesystem;
+ retval = register_cld_notifier();
+ if (retval)
goto out_free_all;
return 0;
out_free_all:
+ unregister_pernet_subsys(&nfsd_net_ops);
+out_free_filesystem:
unregister_filesystem(&nfsd_fs_type);
out_free_exports:
remove_proc_entry("fs/nfs/exports", NULL);
@@ -1561,13 +1563,12 @@ out_free_pnfs:
nfsd4_exit_pnfs();
out_free_slabs:
nfsd4_free_slabs();
-out_unregister_notifier:
- unregister_cld_notifier();
return retval;
}
static void __exit exit_nfsd(void)
{
+ unregister_cld_notifier();
unregister_pernet_subsys(&nfsd_net_ops);
nfsd_drc_slab_free();
remove_proc_entry("fs/nfs/exports", NULL);
@@ -1577,7 +1578,6 @@ static void __exit exit_nfsd(void)
nfsd4_free_slabs();
nfsd4_exit_pnfs();
unregister_filesystem(&nfsd_fs_type);
- unregister_cld_notifier();
}
MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");