From 31b57b87fddf547bf3e98306b41bc82e111396fa Mon Sep 17 00:00:00 2001 From: Haggai Eran Date: Tue, 7 Jul 2015 17:45:12 +0300 Subject: [PATCH] IB/ucma: Fix lockdep warning in ucma_lock_files The ucma_lock_files() locks the mut mutex on two files, e.g. for migrating an ID. Use mutex_lock_nested() to prevent the warning below. ============================================= [ INFO: possible recursive locking detected ] 4.1.0-rc6-hmm+ #40 Tainted: G O --------------------------------------------- pingpong_rpc_se/10260 is trying to acquire lock: (&file->mut){+.+.+.}, at: [] ucma_migrate_id+0xc5/0x248 [rdma_ucm] but task is already holding lock: (&file->mut){+.+.+.}, at: [] ucma_migrate_id+0xbb/0x248 [rdma_ucm] other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&file->mut); lock(&file->mut); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by pingpong_rpc_se/10260: #0: (&file->mut){+.+.+.}, at: [] ucma_migrate_id+0xbb/0x248 [rdma_ucm] stack backtrace: CPU: 0 PID: 10260 Comm: pingpong_rpc_se Tainted: G O 4.1.0-rc6-hmm+ #40 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2007 ffff8801f85b63d0 ffff880195677b58 ffffffff81668f49 0000000000000001 ffffffff825cbbe0 ffff880195677c38 ffffffff810bb991 ffff880100000000 ffff880100000000 ffff880100000001 ffff8801f85b7010 ffffffff8121bee9 Call Trace: [] dump_stack+0x4f/0x6e [] __lock_acquire+0x741/0x1820 [] ? dput+0x29/0x320 [] lock_acquire+0xc8/0x240 [] ? ucma_migrate_id+0xc5/0x248 [rdma_ucm] [] ? mutex_lock_nested+0x291/0x3e0 [] mutex_lock_nested+0x65/0x3e0 [] ? ucma_migrate_id+0xc5/0x248 [rdma_ucm] [] ? trace_hardirqs_on+0xd/0x10 [] ? mutex_unlock+0xe/0x10 [] ucma_migrate_id+0xc5/0x248 [rdma_ucm] [] ucma_write+0xa4/0xb0 [rdma_ucm] [] __vfs_write+0x34/0x100 [] ? __audit_syscall_entry+0xac/0x110 [] ? current_kernel_time+0xc5/0xe0 [] ? security_file_permission+0x23/0x90 [] ? rw_verify_area+0x5d/0xe0 [] vfs_write+0xab/0x120 [] SyS_write+0x59/0xd0 [] ? __audit_syscall_entry+0xac/0x110 [] system_call_fastpath+0x12/0x76 Signed-off-by: Haggai Eran Signed-off-by: Doug Ledford --- drivers/infiniband/core/ucma.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index ad45469f7582..a700cdb13f3d 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -1354,10 +1354,10 @@ static void ucma_lock_files(struct ucma_file *file1, struct ucma_file *file2) /* Acquire mutex's based on pointer comparison to prevent deadlock. */ if (file1 < file2) { mutex_lock(&file1->mut); - mutex_lock(&file2->mut); + mutex_lock_nested(&file2->mut, SINGLE_DEPTH_NESTING); } else { mutex_lock(&file2->mut); - mutex_lock(&file1->mut); + mutex_lock_nested(&file1->mut, SINGLE_DEPTH_NESTING); } } -- GitLab