On Wed, Aug 03, 2016 at 08:54:50PM +0400, Stanislav Kinsburskiy wrote: > Otherwise freezer cgroup state might never become "FROZEN". > > Here is a deadlock scheme for 2 processes in one freezer cgroup, which is > freezing: > > CPU 0 CPU 1 > -------- -------- > do_last > inode_lock(dir->d_inode) > vfs_create > nfs_create > ... > __rpc_execute > rpc_wait_bit_killable > __refrigerator > do_last > inode_lock(dir->d_inode) > > So, the problem is that one process takes directory inode mutex, executes > creation request and goes to refrigerator. > Another one waits till directory lock is released, remains "thawed" and thus > freezer cgroup state never becomes "FROZEN". > > Notes: > 1) Interesting, that this is not a pure deadlock: one can thaw cgroup and then > freeze it again. > 2) The issue was introduced by commit d310310cbff18ec385c6ab4d58f33b100192a96a. > 3) This patch is not aimed to fix the issue, but to show the problem root. > Look like this problem moght be applicable to other hunks from the commit, > mentioned above. > > Signed-off-by: Stanislav Kinsburskiy <skinsbursky@xxxxxxxxxxxxx> I think it's worth adding backtrace as well --- === pid: 708987 === (file_read) [<ffffffff810de47b>] __refrigerator+0x5b/0x190 [<ffffffffa01e6d36>] rpc_wait_bit_killable+0x66/0x80 [sunrpc] [<ffffffffa01e7bf4>] __rpc_execute+0x154/0x420 [sunrpc] [<ffffffffa01e972e>] rpc_execute+0x5e/0xa0 [sunrpc] [<ffffffffa01df220>] rpc_run_task+0x70/0x90 [sunrpc] [<ffffffffa01df290>] rpc_call_sync+0x50/0xc0 [sunrpc] [<ffffffffa035c5cb>] nfs3_rpc_wrapper.constprop.10+0x6b/0xb0 [nfsv3] [<ffffffffa035c6cf>] nfs3_proc_setattr+0xbf/0x140 [nfsv3] [<ffffffffa035db03>] nfs3_proc_create+0x1a3/0x220 [nfsv3] [<ffffffffa036c023>] nfs_create+0x83/0x150 [nfs] [<ffffffff8120639c>] vfs_create+0x8c/0x110 [<ffffffff8120963d>] do_last+0xc0d/0x11d0 [<ffffffff81209cc2>] path_openat+0xc2/0x460 [<ffffffff8120b45b>] do_filp_open+0x4b/0xb0 [<ffffffff811f8c63>] do_sys_open+0xf3/0x1f0 [<ffffffff811f8d7e>] SyS_open+0x1e/0x20 [<ffffffff81643449>] system_call_fastpath+0x16/0x1b [<ffffffffffffffff>] 0xffffffffffffffff === pid: 708988 === (file_read) [<ffffffff81208cb3>] do_last+0x283/0x11d0 [<ffffffff81209cc2>] path_openat+0xc2/0x460 [<ffffffff8120b45b>] do_filp_open+0x4b/0xb0 [<ffffffff811f8c63>] do_sys_open+0xf3/0x1f0 [<ffffffff811f8d7e>] SyS_open+0x1e/0x20 [<ffffffff81643449>] system_call_fastpath+0x16/0x1b [<ffffffffffffffff>] 0xffffffffffffffff -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
