Return-Path: Received: from mail-qg0-f41.google.com ([209.85.192.41]:34365 "EHLO mail-qg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751634AbcD3NPr (ORCPT ); Sat, 30 Apr 2016 09:15:47 -0400 Received: by mail-qg0-f41.google.com with SMTP id 90so37512752qgz.1 for ; Sat, 30 Apr 2016 06:15:46 -0700 (PDT) Message-ID: <1462022142.10011.19.camel@poochiereds.net> Subject: Re: parallel lookups on NFS From: Jeff Layton To: Al Viro Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Trond Myklebust , Linus Torvalds , Anna Schumaker Date: Sat, 30 Apr 2016 09:15:42 -0400 In-Reply-To: <20160429075812.GY25498@ZenIV.linux.org.uk> References: <20160424023453.GK25498@ZenIV.linux.org.uk> <1461501975.5219.40.camel@poochiereds.net> <20160424191835.GL25498@ZenIV.linux.org.uk> <20160429075812.GY25498@ZenIV.linux.org.uk> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, 2016-04-29 at 08:58 +0100, Al Viro wrote: > On Sun, Apr 24, 2016 at 08:18:35PM +0100, Al Viro wrote: > > > > > What we get out of that is fully parallel > > lookup/readdir/sillyunlink - all > > exclusion is on per-name basis (nfs_prime_dcache() vs. nfs_lookup() > > vs. > > nfs_do_call_unlink()). It will require a bit of care in > > atomic_open(), > > though... > > > > I'll play with that a bit and see what can be done... > OK, a bunch of atomic_open cleanups (moderately tested) + > almost untested sillyunlink patch are in vfs.git#untested.nfs. > > It ought to make lookups (and readdir, and !O_CREAT case of > atomic_open) > on NFS really execute in parallel. Folks, please hit that sucker > with > NFS torture tests. In particular, the stuff mentioned in commit > 565277f6 would be interesting to try. I pulled down the branch and built it, and then ran the cthon special tests 100 times in a loop, and ran "ls -l" on the test directory in a loop at the same time. On pass 42, I hit this: [ 1168.630763] general protection fault: 0000 [#1] SMP [ 1168.631617] Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache xfs snd_hda_codec_generic snd_hda_intel snd_hda_codec libcrc32c snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer snd nfsd joydev ppdev soundcore acpi_cpufreq virtio_net pcspkr i2c_piix4 tpm_tis tpm parport_pc parport virtio_balloon floppy pvpanic nfs_acl lockd auth_rpcgss grace sunrpc qxl drm_kms_helper ttm drm virtio_console virtio_blk virtio_pci virtio_ring virtio serio_raw ata_generic pata_acpi [ 1168.638448] CPU: 3 PID: 1850 Comm: op_ren Not tainted 4.6.0-rc1+ #25 [ 1168.639413] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 1168.640146] task: ffff880035cf5400 ti: ffff8800d064c000 task.ti: ffff8800d064c000 [ 1168.641107] RIP: 0010:[] [] kmem_cache_alloc+0x78/0x160 [ 1168.642292] RSP: 0018:ffff8800d064fa90 EFLAGS: 00010246 [ 1168.642978] RAX: 73747365746e7572 RBX: 0000000000000894 RCX: 0000000000000020 [ 1168.643920] RDX: 0000000000318271 RSI: 00000000024080c0 RDI: 000000000001a440 [ 1168.644862] RBP: ffff8800d064fac0 R08: ffff88021fd9a440 R09: ffff880035b82400 [ 1168.645794] R10: 0000000000000000 R11: ffff8800d064fb70 R12: 00000000024080c0 [ 1168.646762] R13: ffffffff81317667 R14: ffff880217001d00 R15: 73747365746e7572 [ 1168.647650] FS: 00007f0cb8295700(0000) GS:ffff88021fd80000(0000) knlGS:0000000000000000 [ 1168.648639] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1168.649330] CR2: 0000000000401090 CR3: 0000000035f9a000 CR4: 00000000000006e0 [ 1168.650239] Stack: [ 1168.650498] 00ff8800026084c0 0000000000000894 ffff880035b82400 ffff8800d064fd14 [ 1168.651509] ffff8800d0650000 ffff880201ca5e38 ffff8800d064fae0 ffffffff81317667 [ 1168.652506] ffffffff81c9b140 ffff880035b82400 ffff8800d064fb00 ffffffff8130ef03 [ 1168.653494] Call Trace: [ 1168.653889] [] selinux_file_alloc_security+0x37/0x60 [ 1168.654728] [] security_file_alloc+0x33/0x50 [ 1168.655447] [] get_empty_filp+0x9a/0x1c0 [ 1168.656231] [] ? copy_to_iter+0x1b6/0x260 [ 1168.656999] [] path_openat+0x2e/0x1660 [ 1168.657645] [] ? current_fs_time+0x23/0x30 [ 1168.658311] [] ? copy_to_iter+0x1b6/0x260 [ 1168.658999] [] ? current_fs_time+0x23/0x30 [ 1168.659742] [] ? touch_atime+0x23/0xa0 [ 1168.660435] [] do_filp_open+0x7e/0xe0 [ 1168.661072] [] ? __vfs_read+0xa7/0xd0 [ 1168.661792] [] ? __vfs_read+0xa7/0xd0 [ 1168.662410] [] ? kmem_cache_alloc+0x34/0x160 [ 1168.663130] [] do_open_execat+0x64/0x150 [ 1168.664100] [] open_exec+0x2b/0x50 [ 1168.664949] [] load_elf_binary+0x29a/0x1670 [ 1168.665880] [] ? get_user_pages_remote+0x54/0x60 [ 1168.666843] [] ? copy_strings.isra.30+0x25c/0x370 [ 1168.667812] [] search_binary_handler+0x9e/0x1d0 [ 1168.668753] [] do_execveat_common.isra.41+0x4fc/0x6d0 [ 1168.669753] [] SyS_execve+0x3a/0x50 [ 1168.670560] [] do_syscall_64+0x62/0x110 [ 1168.671384] [] entry_SYSCALL64_slow_path+0x25/0x25 [ 1168.672305] Code: 49 83 78 10 00 4d 8b 38 0f 84 bd 00 00 00 4d 85 ff 0f 84 b4 00 00 00 49 63 46 20 49 8b 3e 4c 01 f8 40 f6 c7 0f 0f 85 cf 00 00 00 <48> 8b 18 48 8d 4a 01 4c 89 f8 65 48 0f c7 0f 0f 94 c0 84 c0 74 [ 1168.676071] RIP [] kmem_cache_alloc+0x78/0x160 [ 1168.677008] RSP [ 1168.679699] general protection fault: 0000 [#2] kmem_cache corruption maybe? (gdb) list *(kmem_cache_alloc+0x78) 0xffffffff811f6488 is in kmem_cache_alloc (mm/slub.c:245). 240 * Core slab cache functions 241 *******************************************************************/ 242 243 static inline void *get_freepointer(struct kmem_cache *s, void *object) 244 { 245 return *(void **)(object + s->offset); 246 } 247 248 static void prefetch_freepointer(const struct kmem_cache *s, void *object) 249 {