Return-Path: Received: from mail-vn0-f44.google.com ([209.85.216.44]:34265 "EHLO mail-vn0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752733AbbE1O4P convert rfc822-to-8bit (ORCPT ); Thu, 28 May 2015 10:56:15 -0400 Received: by vnbf129 with SMTP id f129so4886422vnb.1 for ; Thu, 28 May 2015 07:56:14 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <55672441.4040700@redhat.com> References: <5564732E.4090607@redhat.com> <20150528075332.6945fd09@synchrony.poochiereds.net> <55672441.4040700@redhat.com> Date: Thu, 28 May 2015 10:56:14 -0400 Message-ID: Subject: Re: swap: nfs: Sleeping function called from an rcu read section in nfs_swap_activate From: Trond Myklebust To: Jerome Marchand Cc: Jeff Layton , Mel Gorman , Jeff Layton , Linux-MM , linux-kernel , Linux NFS Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, May 28, 2015 at 10:20 AM, Jerome Marchand wrote: > On 05/28/2015 01:53 PM, Jeff Layton wrote: >> On Tue, 26 May 2015 15:20:46 +0200 >> Jerome Marchand wrote: >> >>> >>> Commit dad2b015 added an rcu read lock around the call to xs_swapper() >>> in nfs_activate()/deactivate(), which can sleep, thus raising a bug at >>> each swapon and swapoff over NFS. >>> I'm not sure if this is related or not, but swapoff also triggers the >>> WARN_ON(sk->sk_forward_alloc) in sk_clear_memalloc(). >>> >>> [ 243.668067] =============================== >>> [ 243.668665] [ INFO: suspicious RCU usage. ] >>> [ 243.669293] 4.1.0-rc1-lock_stat-dbg-next-20150430+ #235 Not tainted >>> [ 243.670301] ------------------------------- >>> [ 243.670905] include/linux/rcupdate.h:570 Illegal context switch in RCU read-side critical section! >>> [ 243.672163] >>> other info that might help us debug this: >>> >>> [ 243.673025] >>> rcu_scheduler_active = 1, debug_locks = 0 >>> [ 243.673565] 2 locks held by swapon/1176: >>> [ 243.673893] #0: (&sb->s_type->i_mutex_key#17){+.+.+.}, at: [] SyS_swapon+0x2b0/0x1000 >>> [ 243.674758] #1: (rcu_read_lock){......}, at: [] nfs_swap_activate+0x5/0x180 [nfs] >>> [ 243.675591] >>> stack backtrace: >>> [ 243.675957] CPU: 0 PID: 1176 Comm: swapon Not tainted 4.1.0-rc1-lock_stat-dbg-next-20150430+ #235 >>> [ 243.676687] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 >>> [ 243.677179] 0000000000000000 00000000ef88d841 ffff88003327bcd8 ffffffff818861f0 >>> [ 243.677854] 0000000000000000 ffff880078e38000 ffff88003327bd08 ffffffff8110d237 >>> [ 243.678514] 0000000000000000 ffffffff81c650e4 0000000000000268 ffff880078e38000 >>> [ 243.679171] Call Trace: >>> [ 243.679383] [] dump_stack+0x4c/0x65 >>> [ 243.679811] [] lockdep_rcu_suspicious+0xe7/0x120 >>> [ 243.680348] [] ___might_sleep+0xaf/0x250 >>> [ 243.680815] [] __might_sleep+0x4d/0x90 >>> [ 243.681279] [] mutex_lock_nested+0x47/0x430 >>> [ 243.681762] [] static_key_slow_inc+0x7c/0xc0 >>> [ 243.682264] [] sk_set_memalloc+0x27/0x30 >>> [ 243.682736] [] xs_swapper+0x54/0x60 [sunrpc] >>> [ 243.683238] [] nfs_swap_activate+0x93/0x180 [nfs] >>> [ 243.683760] [] ? nfs_swap_activate+0x5/0x180 [nfs] >>> [ 243.684316] [] SyS_swapon+0xad4/0x1000 >>> [ 243.684766] [] ? syscall_return+0x16/0x59 >>> [ 243.685245] [] system_call_fastpath+0x12/0x76 >>> [ 243.685743] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:616 >>> [ 243.686439] in_atomic(): 1, irqs_disabled(): 0, pid: 1176, name: swapon >>> [ 243.687053] INFO: lockdep is turned off. >>> [ 243.687429] CPU: 0 PID: 1176 Comm: swapon Not tainted 4.1.0-rc1-lock_stat-dbg-next-20150430+ #235 >>> [ 243.688313] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 >>> [ 243.688845] 0000000000000000 00000000ef88d841 ffff88003327bd08 ffffffff818861f0 >>> [ 243.689570] 0000000000000000 ffff880078e38000 ffff88003327bd38 ffffffff810df29c >>> [ 243.690353] ffff880000000001 ffffffff81c650e4 0000000000000268 0000000000000000 >>> [ 243.691057] Call Trace: >>> [ 243.691315] [] dump_stack+0x4c/0x65 >>> [ 243.691785] [] ___might_sleep+0x18c/0x250 >>> [ 243.692306] [] __might_sleep+0x4d/0x90 >>> [ 243.692807] [] mutex_lock_nested+0x47/0x430 >>> [ 243.693346] [] static_key_slow_inc+0x7c/0xc0 >>> [ 243.693887] [] sk_set_memalloc+0x27/0x30 >>> [ 243.694416] [] xs_swapper+0x54/0x60 [sunrpc] >>> [ 243.694959] [] nfs_swap_activate+0x93/0x180 [nfs] >>> [ 243.695535] [] ? nfs_swap_activate+0x5/0x180 [nfs] >>> [ 243.696193] [] SyS_swapon+0xad4/0x1000 >>> [ 243.696699] [] ? syscall_return+0x16/0x59 >>> [ 243.697299] [] system_call_fastpath+0x12/0x76 >>> [ 243.702101] Adding 524284k swap on /mnt/swapfile512. Priority:-2 extents:1 across:524284k FS >>> [ 325.151350] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:616 >>> [ 325.152688] in_atomic(): 1, irqs_disabled(): 0, pid: 1199, name: swapoff >>> [ 325.153737] INFO: lockdep is turned off. >>> [ 325.154457] CPU: 1 PID: 1199 Comm: swapoff Not tainted 4.1.0-rc1-lock_stat-dbg-next-20150430+ #235 >>> [ 325.156204] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 >>> [ 325.157120] 0000000000000000 00000000a7682b83 ffff88007ac3fce8 ffffffff818861f0 >>> [ 325.158361] 0000000000000000 ffff880032434c00 ffff88007ac3fd18 ffffffff810df29c >>> [ 325.159592] 0000000000000000 ffffffff81c650e4 0000000000000268 0000000000000000 >>> [ 325.160798] Call Trace: >>> [ 325.161251] [] dump_stack+0x4c/0x65 >>> [ 325.162071] [] ___might_sleep+0x18c/0x250 >>> [ 325.163073] [] __might_sleep+0x4d/0x90 >>> [ 325.163934] [] mutex_lock_nested+0x47/0x430 >>> [ 325.164927] [] atomic_dec_and_mutex_lock+0x4f/0x70 >>> [ 325.166020] [] __static_key_slow_dec+0x27/0xc0 >>> [ 325.166942] [] static_key_slow_dec+0x26/0x50 >>> [ 325.167955] [] sk_clear_memalloc+0x2f/0x80 >>> [ 325.169075] [] xs_swapper+0x41/0x60 [sunrpc] >>> [ 325.170241] [] nfs_swap_deactivate+0x87/0x170 [nfs] >>> [ 325.171276] [] ? nfs_swap_deactivate+0x5/0x170 [nfs] >>> [ 325.172349] [] destroy_swap_extents+0x77/0x90 >>> [ 325.173754] [] SyS_swapoff+0x215/0x600 >>> [ 325.174726] [] ? trace_hardirqs_on_thunk+0x17/0x19 >>> [ 325.175971] [] system_call_fastpath+0x12/0x76 >>> [ 325.178052] ------------[ cut here ]------------ >>> [ 325.178892] WARNING: CPU: 1 PID: 1199 at net/core/sock.c:364 sk_clear_memalloc+0x51/0x80() >>> [ 325.180363] Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack ebtable_nat ebtable_broute bridge stp llc ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw iosf_mbi crct10dif_pclmul crc32_pclmul crc32c_intel ppdev ghash_clmulni_intel joydev nfsd parport_pc pcspkr virtio_console serio_raw virtio_balloon parport pvpanic i2c_piix4 acpi_cpufreq auth_rpcgss nfs_acl lockd grace sunrpc virtio_blk qxl virtio_net drm_kms_helper ttm drm virtio_pci virtio_ring virtio ata_generic pata_acpi floppy >>> [ 325.192279] CPU: 1 PID: 1199 Comm: swapoff Not tainted 4.1.0-rc1-lock_stat-dbg-next-20150430+ #235 >>> [ 325.193605] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 >>> [ 325.194491] 0000000000000000 00000000a7682b83 ffff88007ac3fdf8 ffffffff818861f0 >>> [ 325.195692] 0000000000000000 0000000000000000 ffff88007ac3fe38 ffffffff810af5ca >>> [ 325.196891] ffff88007ac3fe78 ffff88007b068000 ffff88007b484a00 ffff88007b484aa8 >>> [ 325.198119] Call Trace: >>> [ 325.198555] [] dump_stack+0x4c/0x65 >>> [ 325.199380] [] warn_slowpath_common+0x8a/0xc0 >>> [ 325.200601] [] warn_slowpath_null+0x1a/0x20 >>> [ 325.201536] [] sk_clear_memalloc+0x51/0x80 >>> [ 325.202468] [] xs_swapper+0x41/0x60 [sunrpc] >>> [ 325.203398] [] nfs_swap_deactivate+0x87/0x170 [nfs] >>> [ 325.204426] [] ? nfs_swap_deactivate+0x5/0x170 [nfs] >>> [ 325.205456] [] destroy_swap_extents+0x77/0x90 >>> [ 325.206406] [] SyS_swapoff+0x215/0x600 >>> [ 325.207287] [] ? trace_hardirqs_on_thunk+0x17/0x19 >>> [ 325.208300] [] system_call_fastpath+0x12/0x76 >>> [ 325.209248] ---[ end trace 13f1014b56e5e711 ]--- >>> >> >> Jerome, >> >> Can you test the attached patch and let me know if this fixes the >> problem? If so, then I'll send it on "officially" to Trond. >> >> Thanks, >> > > It doesn't build: xprt_put() is not exported. > Jeff, could you please change xs_swapper to take a struct rpc_clnt argument. There is absolutely no reason for it to be taking a struct rpc_xprt. Thanks Trond