On Sat, 2016-04-30 at 19:23 -0400, Jeff Layton wrote:
> On Sat, 2016-04-30 at 21:57 +0100, Al Viro wrote:
> >
> > On Sat, Apr 30, 2016 at 04:39:25PM -0400, Jeff Layton wrote:
> >
> > >
> > >
> > > Attached. Also I ran the same test on a 4.6.0-rc1 kernel and it
> > > worked
> > > fine, so it does seem to be a regression introduced somewhere in
> > > your
> > > patch pile. Also, FWIW the machine is a KVM guest.
> > OK... Could you try #work.lookups on your setup? That doesn't
> > contain the
> > last commit; the deadlock ought to be dealt with, though. I'm trying
> > to
> > reproduce the corruption with KASAN enabled, will try your config
> > once that's
> > finished...
>
> Here's what I got with your untested.nfs branch + KASAN:
>
> [ 192.453252] BUG: unable to handle kernel paging request at ffff814bf270ffff
> [ 192.454102] IP: [] deactivate_slab+0xab/0x3e0
> [ 192.454795] PGD 0
> [ 192.455040] Oops: 0000 [#1] SMP KASAN
> [ 192.455469] Modules linked in: nfsv3 nfs fscache xfs snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hda_core libcrc32c snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer nfsd joydev snd acpi_cpufreq ppdev parport_pc tpm_tis virtio_net soundcore parport tpm pcspkr virtio_balloon pvpanic i2c_piix4 nfs_acl lockd auth_rpcgss grace sunrpc qxl drm_kms_helper virtio_console virtio_blk ttm drm serio_raw virtio_pci ata_generic virtio_ring pata_acpi virtio floppy
> [ 192.460993] CPU: 0 PID: 8628 Comm: rm Not tainted 4.6.0-rc1+ #29
> [ 192.461679] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> [ 192.462359] task: ffff8801bf990000 ti: ffff8800c7e88000 task.ti: ffff8800c7e88000
> [ 192.463372] RIP: 0010:[] [] deactivate_slab+0xab/0x3e0
> [ 192.464266] RSP: 0018:ffff8800c7e8f550 EFLAGS: 00010002
> [ 192.464839] RAX: 0000000000000000 RBX: ffff8801d6c02200 RCX: 00000001801a0019
> [ 192.465646] RDX: ffff8800c5949c2e RSI: ffffea0003165200 RDI: ffffea0003165200
> [ 192.466443] RBP: ffff8800c7e8f650 R08: ffff8800c5948750 R09: 000000000000801a
> [ 192.467319] R10: ffff8800c5948750 R11: ffffed0037f53c7f R12: ffff8801d6c02208
> [ 192.468282] R13: ffff814bf270ffff R14: ffff814bf270ffff R15: ffffea0003165200
> [ 192.469064] FS: 00007f8ae54d7700(0000) GS:ffff8801d7000000(0000) knlGS:0000000000000000
> [ 192.469919] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 192.470528] CR2: ffff814bf270ffff CR3: 00000000c5950000 CR4: 00000000000006f0
> [ 192.471337] Stack:
> [ 192.471567] ffff8800c7e8f58c 00000000801a001a ffff8801d7007fc0 ffff8801bf990000
> [ 192.472453] 0000000000000000 ffff8800c7e88000 ffff8800c7e8f5c0 0000000003165200
> [ 192.473388] 0000000fc7e8f650 ffff8801d6c01e00 ffffffffa098b3df ffff8801bf990000
> [ 192.474349] Call Trace:
> [ 192.474641] [] ? nfs_readdir_page_filler+0x65f/0x1430 [nfs]
> [ 192.475456] [] ? nfs_readdir_page_filler+0x65f/0x1430 [nfs]
> [ 192.476246] [] ? save_stack_trace+0x2b/0x50
> [ 192.476872] [] ? set_track+0x74/0x120
> [ 192.477453] [] ? alloc_debug_processing+0x73/0x1b0
> [ 192.478143] [] ___slab_alloc+0x4ff/0x520
> [ 192.478742] [] ? memcpy+0x36/0x40
> [ 192.479309] [] ? nfs_readdir_page_filler+0x65f/0x1430 [nfs]
> [ 192.480084] [] ? nfs3_decode_dirent+0x773/0xd90 [nfsv3]
> [ 192.480846] [] ? nfs_readdir_page_filler+0x65f/0x1430 [nfs]
> [ 192.481642] [] __slab_alloc+0x20/0x40
> [ 192.482209] [] __kmalloc_track_caller+0x167/0x1d0
> [ 192.482884] [] kmemdup+0x20/0x50
> [ 192.483478] [] nfs_readdir_page_filler+0x65f/0x1430 [nfs]
> [ 192.484226] [] ? __slab_free+0x9a/0x250
> [ 192.484851] [] ? nfs_do_filldir+0x730/0x730 [nfs]
> [ 192.485916] [] ? nfs3_proc_readdir+0x2a7/0x4e0 [nfsv3]
> [ 192.486990] [] ? ___slab_alloc+0x4ff/0x520
> [ 192.487965] [] ? nfs3_proc_rmdir+0x2f0/0x2f0 [nfsv3]
> [ 192.489009] [] ? kasan_unpoison_shadow+0x36/0x50
> [ 192.490075] [] ? alloc_pages_current+0xd3/0x290
> [ 192.491144] [] nfs_readdir_xdr_to_array+0x59d/0xaa0 [nfs]
> [ 192.492346] [] ? nfs_readdir_page_filler+0x1430/0x1430 [nfs]
> [ 192.493506] [] ? radix_tree_lookup_slot+0x58/0x90
> [ 192.494564] [] ? alloc_pages_current+0x44/0x290
> [ 192.495558] [] ? add_to_page_cache_locked+0x20/0x20
> [ 192.496593] [] nfs_readdir_filler+0x6a/0x1c0 [nfs]
> [ 192.497595] [] do_read_cache_page+0x22e/0x6a0
> [ 192.498568] [] ? nfs_readdir_xdr_to_array+0xaa0/0xaa0 [nfs]
> [ 192.499646] [] read_cache_page+0x40/0x70
> [ 192.500547] [] nfs_readdir+0x456/0x1680 [nfs]
> [ 192.501501] [] ? lru_cache_add_active_or_unevictable+0xcb/0x260
> [ 192.502616] [] ? nfs_readdir_filler+0x1c0/0x1c0 [nfs]
> [ 192.503634] [] ? nfs3_xdr_dec_getattr3res+0xb0/0xb0 [nfsv3]
> [ 192.504714] [] iterate_dir+0x3f3/0x5b0
> [ 192.505591] [] SyS_getdents+0xf8/0x1a0
> [ 192.506473] [] ? enter_from_user_mode+0x50/0x50
> [ 192.507454] [] ? SyS_old_readdir+0x100/0x100
> [ 192.508412] [] ? iterate_dir+0x5b0/0x5b0
> [ 192.509332] [] ? syscall_trace_enter_phase2+0xf1/0x510
> [ 192.510377] [] ? SyS_old_readdir+0x100/0x100
> [ 192.511351] [] do_syscall_64+0x19a/0x410
> [ 192.512258] [] ? context_tracking_enter+0x1d/0x20
> [ 192.513275] [] entry_SYSCALL64_slow_path+0x25/0x25
> [ 192.514271] Code: 8b 57 10 49 8b 4f 18 49 89 54 05 00 48 89 4c 24 68 66 83 6c 24 68 01 80 7c 24 6b 00 78 c6 0f 0b 48 63 43 20 49 8b 57 10 4d 89 f5 <49> 8b 0c 06 48 85 c9 74 05 49 89 ce eb ca 48 8b 7c 24 48 45 31
> [ 192.518193] RIP [] deactivate_slab+0xab/0x3e0
> [ 192.519099] RSP
> [ 192.519738] CR2: ffff814bf270ffff
> [ 192.520410] ---[ end trace a406a29677c40c04 ]---
>
> Same spot, apparently:
>
> (gdb) list *(deactivate_slab+0xab)
> 0xffffffff8156622b is in deactivate_slab (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 {
>
> IIRC, when I looked at this code last time, my take was that it wasn't
> so much that the slab objects were getting corrupted, but rather the
> cache metadata.
>
...and then a little while later, this pops:
[ 650.375768] ==================================================================
[ 650.378114] BUG: KASAN: slab-out-of-bounds in memcpy+0x28/0x40 at addr ffff8800c5949c2e
[ 650.380379] Write of size 6 by task systemd/1
[ 650.381756] =============================================================================
[ 650.383894] BUG kmalloc-8 (Tainted: G D ): kasan: bad access detected
[ 650.386032] -----------------------------------------------------------------------------
[ 650.386032]
[ 650.389053] INFO: Allocated in nfs_readdir_page_filler+0x65f/0x1430 [nfs] age=457944 cpu=0 pid=8626
[ 650.391395] ___slab_alloc+0x4de/0x520
[ 650.392730] __slab_alloc+0x20/0x40
[ 650.393986] 0x8750ffff8156a837
[ 650.395171] 0xffffffff8800c594
[ 650.396387] nfs_readdir_page_filler+0x65f/0x1430 [nfs]
[ 650.397871] nfs_readdir_xdr_to_array+0x59d/0xaa0 [nfs]
[ 650.399455] nfs_readdir_filler+0x6a/0x1c0 [nfs]
[ 650.400856] do_read_cache_page+0x22e/0x6a0
[ 650.402183] read_cache_page+0x40/0x70
[ 650.403539] nfs_readdir+0x456/0x1680 [nfs]
[ 650.404971] iterate_dir+0x3f3/0x5b0
[ 650.406172] SyS_getdents+0xf8/0x1a0
[ 650.407323] do_syscall_64+0x19a/0x410
[ 650.408453] return_from_SYSCALL_64+0x0/0x6a
[ 650.409699] INFO: Freed in nfs_readdir_clear_array+0xdf/0x1d0 [nfs] age=457957 cpu=0 pid=8626
[ 650.411805] __slab_free+0x17f/0x250
[ 650.412935] kfree+0x173/0x190
[ 650.413983] nfs_readdir_clear_array+0xdf/0x1d0 [nfs]
[ 650.415364] cache_page_release.isra.27+0xf2/0x160 [nfs]
[ 650.416794] nfs_do_filldir+0x3af/0x730 [nfs]
[ 650.418011] nfs_readdir+0x764/0x1680 [nfs]
[ 650.419165] iterate_dir+0x3f3/0x5b0
[ 650.420260] SyS_getdents+0xf8/0x1a0
[ 650.421320] do_syscall_64+0x19a/0x410
[ 650.422401] return_from_SYSCALL_64+0x0/0x6a
[ 650.423564] INFO: Slab 0xffffea0003165200 objects=26 used=26 fp=0x (null) flags=0x3fff8000004080
[ 650.425673] INFO: Object 0xffff8800c5949c08 @offset=7176 fp=0xffff8800c5948fd8
[ 650.425673]
[ 650.427984] Bytes b4 ffff8800c5949bf8: 00 00 00 00 b2 21 00 00 10 59 fe ff 00 00 00 00 .....!...Y......
[ 650.430030] Object ffff8800c5949c08: d8 8f 94 c5 00 88 ff ff ........
[ 650.431896] CPU: 0 PID: 1 Comm: systemd Tainted: G B D 4.6.0-rc1+ #29
[ 650.433537] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 650.434982] ffffea0003165200 ffff8801d5e97978 ffffffff81a72334 ffff8801d6c02200
[ 650.436722] ffff8800c5949c08 ffff8801d5e979a8 ffffffff815641a2 ffff8801d6c02200
[ 650.438416] ffffea0003165200 ffff8800c5949c08 0000000000000002 ffff8801d5e979d0
[ 650.440271] Call Trace:
[ 650.441108] [<ffffffff81a72334>] dump_stack+0x63/0x8f
[ 650.442345] [<ffffffff815641a2>] print_trailer+0x112/0x1a0
[ 650.443669] [<ffffffff81569a04>] object_err+0x34/0x40
[ 650.444908] [<ffffffff8156bd54>] kasan_report_error+0x224/0x530
[ 650.446297] [<ffffffff8271dd0e>] ? _raw_spin_unlock_irqrestore+0xe/0x10
[ 650.447975] [<ffffffff8156c459>] kasan_report+0x39/0x40
[ 650.449195] [<ffffffff8156b701>] ? kasan_poison_slab+0x61/0x70
[ 650.450687] [<ffffffff8156b5e8>] ? memcpy+0x28/0x40
[ 650.451815] [<ffffffff8156b1dd>] __asan_storeN+0x12d/0x180
[ 650.453059] [<ffffffff8156b5e8>] memcpy+0x28/0x40
[ 650.454194] [<ffffffff814bf209>] kstrdup+0x49/0x60
[ 650.455333] [<ffffffff814bf243>] kstrdup_const+0x23/0x30
[ 650.456513] [<ffffffff817059dc>] __kernfs_new_node+0x2c/0x280
[ 650.457690] [<ffffffff81708b03>] kernfs_new_node+0x63/0xf0
[ 650.458822] [<ffffffff8170d42c>] __kernfs_create_file+0x2c/0x1e0
[ 650.460062] [<ffffffff81317657>] cgroup_addrm_files+0x2a7/0x850
[ 650.461303] [<ffffffff813173b0>] ? cgroup_idr_alloc.constprop.34+0x70/0x70
[ 650.462672] [<ffffffff81312ef0>] ? cgroup_file_name+0x1f0/0x1f0
[ 650.463853] [<ffffffff81318082>] css_populate_dir+0x2f2/0x3d0
[ 650.464918] [<ffffffff81325a74>] cgroup_mkdir+0x5a4/0x7b0
[ 650.466003] [<ffffffff813254d0>] ? cgroup_rmdir+0x40/0x40
[ 650.467107] [<ffffffff8170891d>] kernfs_iop_mkdir+0x14d/0x240
[ 650.468261] [<ffffffff815c8bbf>] vfs_mkdir+0x25f/0x470
[ 650.469331] [<ffffffff815d9366>] SyS_mkdir+0x196/0x200
[ 650.470407] [<ffffffff815d91d0>] ? SyS_mkdirat+0x200/0x200
[ 650.471526] [<ffffffff815d91d0>] ? SyS_mkdirat+0x200/0x200
[ 650.472635] [<ffffffff810072fa>] do_syscall_64+0x19a/0x410
[ 650.473699] [<ffffffff81460bfd>] ? context_tracking_enter+0x1d/0x20
[ 650.474872] [<ffffffff8271e321>] entry_SYSCALL64_slow_path+0x25/0x25
[ 650.476083] Memory state around the buggy address:
[ 650.477101] ffff8800c5949b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 650.478412] ffff8800c5949b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 650.479687] >ffff8800c5949c00: fc fb fc fc fc 00 fc fc fc fc fc fc fc fc fc fc
[ 650.480929] ^
[ 650.481896] ffff8800c5949c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 650.483227] ffff8800c5949d00: fc fc fc fc fc fc fc fc fb fc fc fc fc fc fc fc
[ 650.484541] ==================================================================
--
Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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