5.4-stable review patch. If anyone has any objections, please let me know.
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From: Yang Erkun yangerkun@huawei.com
commit 98100e88dd8865999dc6379a3356cd799795fe7b upstream.
The action force umount(umount -f) will attempt to kill all rpc_task even umount operation may ultimately fail if some files remain open. Consequently, if an action attempts to open a file, it can potentially send two rpc_task to nfs server.
NFS CLIENT thread1 thread2 open("file") ... nfs4_do_open _nfs4_do_open _nfs4_open_and_get_state _nfs4_proc_open nfs4_run_open_task /* rpc_task1 */ rpc_run_task rpc_wait_for_completion_task
umount -f nfs_umount_begin rpc_killall_tasks rpc_signal_task rpc_task1 been wakeup and return -512 _nfs4_do_open // while loop ... nfs4_run_open_task /* rpc_task2 */ rpc_run_task rpc_wait_for_completion_task
While processing an open request, nfsd will first attempt to find or allocate an nfs4_openowner. If it finds an nfs4_openowner that is not marked as NFS4_OO_CONFIRMED, this nfs4_openowner will released. Since two rpc_task can attempt to open the same file simultaneously from the client to server, and because two instances of nfsd can run concurrently, this situation can lead to lots of memory leak. Additionally, when we echo 0 to /proc/fs/nfsd/threads, warning will be triggered.
NFS SERVER nfsd1 nfsd2 echo 0 > /proc/fs/nfsd/threads
nfsd4_open nfsd4_process_open1 find_or_alloc_open_stateowner // alloc oo1, stateid1 nfsd4_open nfsd4_process_open1 find_or_alloc_open_stateowner // find oo1, without NFS4_OO_CONFIRMED release_openowner unhash_openowner_locked list_del_init(&oo->oo_perclient) // cannot find this oo // from client, LEAK!!! alloc_stateowner // alloc oo2
nfsd4_process_open2 init_open_stateid // associate oo1 // with stateid1, stateid1 LEAK!!! nfs4_get_vfs_file // alloc nfsd_file1 and nfsd_file_mark1 // all LEAK!!!
nfsd4_process_open2 ...
write_threads ... nfsd_destroy_serv nfsd_shutdown_net nfs4_state_shutdown_net nfs4_state_destroy_net destroy_client __destroy_client // won't find oo1!!! nfsd_shutdown_generic nfsd_file_cache_shutdown kmem_cache_destroy for nfsd_file_slab and nfsd_file_mark_slab // bark since nfsd_file1 // and nfsd_file_mark1 // still alive
======================================================================= BUG nfsd_file (Not tainted): Objects remaining in nfsd_file on __kmem_cache_shutdown() -----------------------------------------------------------------------
Slab 0xffd4000004438a80 objects=34 used=1 fp=0xff11000110e2ad28 flags=0x17ffffc0000240(workingset|head|node=0|zone=2|lastcpupid=0x1fffff) CPU: 4 UID: 0 PID: 757 Comm: sh Not tainted 6.12.0-rc6+ #19 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x53/0x70 slab_err+0xb0/0xf0 __kmem_cache_shutdown+0x15c/0x310 kmem_cache_destroy+0x66/0x160 nfsd_file_cache_shutdown+0xac/0x210 [nfsd] nfsd_destroy_serv+0x251/0x2a0 [nfsd] nfsd_svc+0x125/0x1e0 [nfsd] write_threads+0x16a/0x2a0 [nfsd] nfsctl_transaction_write+0x74/0xa0 [nfsd] vfs_write+0x1ae/0x6d0 ksys_write+0xc1/0x160 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e
Disabling lock debugging due to kernel taint Object 0xff11000110e2ac38 @offset=3128 Allocated in nfsd_file_do_acquire+0x20f/0xa30 [nfsd] age=1635 cpu=3 pid=800 nfsd_file_do_acquire+0x20f/0xa30 [nfsd] nfsd_file_acquire_opened+0x5f/0x90 [nfsd] nfs4_get_vfs_file+0x4c9/0x570 [nfsd] nfsd4_process_open2+0x713/0x1070 [nfsd] nfsd4_open+0x74b/0x8b0 [nfsd] nfsd4_proc_compound+0x70b/0xc20 [nfsd] nfsd_dispatch+0x1b4/0x3a0 [nfsd] svc_process_common+0x5b8/0xc50 [sunrpc] svc_process+0x2ab/0x3b0 [sunrpc] svc_handle_xprt+0x681/0xa20 [sunrpc] nfsd+0x183/0x220 [nfsd] kthread+0x199/0x1e0 ret_from_fork+0x31/0x60 ret_from_fork_asm+0x1a/0x30
Add nfs4_openowner_unhashed to help found unhashed nfs4_openowner, and break nfsd4_open process to fix this problem.
Cc: stable@vger.kernel.org # v5.4+ Reviewed-by: Jeff Layton jlayton@kernel.org Signed-off-by: Yang Erkun yangerkun@huawei.com Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/nfsd/nfs4state.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
--- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1456,6 +1456,14 @@ static void release_open_stateid(struct free_ol_stateid_reaplist(&reaplist); }
+static bool nfs4_openowner_unhashed(struct nfs4_openowner *oo) +{ + lockdep_assert_held(&oo->oo_owner.so_client->cl_lock); + + return list_empty(&oo->oo_owner.so_strhash) && + list_empty(&oo->oo_perclient); +} + static void unhash_openowner_locked(struct nfs4_openowner *oo) { struct nfs4_client *clp = oo->oo_owner.so_client; @@ -4266,6 +4274,12 @@ retry: spin_lock(&oo->oo_owner.so_client->cl_lock); spin_lock(&fp->fi_lock);
+ if (nfs4_openowner_unhashed(oo)) { + mutex_unlock(&stp->st_mutex); + stp = NULL; + goto out_unlock; + } + retstp = nfsd4_find_existing_open(fp, open); if (retstp) goto out_unlock; @@ -5077,6 +5091,11 @@ nfsd4_process_open2(struct svc_rqst *rqs
if (!stp) { stp = init_open_stateid(fp, open); + if (!stp) { + status = nfserr_jukebox; + goto out; + } + if (!open->op_stp) new_stp = true; }