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Date:   Tue, 17 Apr 2018 14:22:58 +0200
From:   Jan Kara <jack@suse.cz>
To:     Pavlos Parissis <pavlos.parissis@gmail.com>
Cc:     Jan Kara <jack@suse.cz>, mszeredi@redhat.com, amir73il@gmail.com,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: kernel 4.14.x crash around fsnotify_mark_connector
Message-ID: <20180417122258.gj25idq7w7xm5dgc@quack2.suse.cz>
References: <e7323798-3175-3d27-fdd1-349f1422cb26@gmail.com>
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Hi,

On Tue 17-04-18 12:39:32, Pavlos Parissis wrote:
> In one of our production servers where we run kernel version 4.14.32, I noticed
> the following:

Thanks for the report! So I believe this is the same underlying problem as
for the softlockups you were observing - there I believe the linked list
just gets corrupted which causes the list iteration to never finish. But
this more points to a place where could be some use-after-free issues
(either in fsnotify or somewhere else). I'll look into the code.

								Honza

> 
> ----
> [138630.417246] cache_from_obj: Wrong slab cache. fsnotify_mark_connector but
> object is from kmalloc-2048(361:anycast-healthchecker.service)
> [138630.477075] ------------[ cut here ]------------
> [138630.500028] WARNING: CPU: 14 PID: 26002 at mm/slab.h:377
> kmem_cache_free+0x133/0x1c0
> [138630.538130] Modules linked in: netconsole binfmt_misc sctp_diag sctp dccp_diag
> dccp tcp_diag udp_diag inet_diag unix_diag cfg80211 rfkill 8021q garp mrp xfs loop
> x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass
> crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc aesni_intel crypto_simd
> glue_helper cryptd iTCO_wdt intel_cstate hpwdt hpilo iTCO_vendor_support sg
> intel_rapl_perf ipmi_si pcspkr ioatdma shpchp lpc_ich i2c_i801 ipmi_devintf dca
> mfd_core wmi ipmi_msghandler nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables
> ext4 mbcache jbd2 i2c_algo_bit sd_mod drm_kms_helper syscopyarea sysfillrect
> sysimgblt fb_sys_fops ttm bnx2x serio_raw mdio libcrc32c crc32c_intel hpsa ptp drm
> scsi_transport_sas pps_core dm_mirror dm_region_hash dm_log dm_mod dax
> [138630.871763] CPU: 14 PID: 26002 Comm: kworker/u66:3 Not tainted
> 4.14.32-1.el7.x86_64 #1
> [138630.910864] Hardware name: HP ProLiant BL460c Gen9, BIOS I36 10/25/2017
> [138630.943498] Workqueue: events_unbound fsnotify_connector_destroy_workfn
> [138630.976569] task: ffff88203b62ae80 task.stack: ffffc90008a20000
> [138631.005895] RIP: 0010:kmem_cache_free+0x133/0x1c0
> [138631.029230] RSP: 0018:ffffc90008a23e20 EFLAGS: 00010246
> [138631.055217] RAX: 000000000000007c RBX: ffff882000000000 RCX: 0000000000000000
> [138631.091346] RDX: 0000000000000000 RSI: ffff88203f3969d8 RDI: ffff88203f3969d8
> [138631.127139] RBP: ffffc90008a23e38 R08: 0000000000000001 R09: 000000000000057d
> [138631.162575] R10: ffff88102b906cf0 R11: ffff88102b913ea0 R12: ffff88103f579980
> [138631.198018] R13: ffff88203bd57c00 R14: ffff88203bd63f00 R15: ffffffff82128388
> [138631.233371] FS:  0000000000000000(0000) GS:ffff88203f380000(0000)
> knlGS:0000000000000000
> [138631.273426] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [138631.301980] CR2: 0000000003600fd8 CR3: 000000000200a006 CR4: 00000000003606e0
> [138631.338783] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [138631.374525] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [138631.409797] Call Trace:
> [138631.422387]  fsnotify_connector_destroy_workfn+0x68/0x80
> [138631.448516]  process_one_work+0x15c/0x380
> [138631.468352]  worker_thread+0x4d/0x3e0
> [138631.486705]  kthread+0x10c/0x140
> [138631.503091]  ? max_active_store+0x80/0x80
> [138631.523217]  ? __kthread_parkme+0x70/0x70
> [138631.543338]  ? do_syscall_64+0x79/0x1b0
> [138631.562518]  ret_from_fork+0x35/0x40
> [138631.580199] Code: 4c 3b a7 d8 00 00 00 0f 84 11 ff ff ff 48 8b 4f 60 49 8b 54
> 24 60 48 c7 c6 c0 19 c3 81 48 c7 c7 c0 9c e7 81 31 c0 e8 90 a5 eb ff <0f> 0b4c 89
> e7 e9 e9 fe ff ff 65 8b 05 2c 3c de 7e 89 c0 48 0f
> [138631.672489] ---[ end trace 6748d86d682915c2 ]---
> [138631.695691] cache_from_obj: Wrong slab cache. fsnotify_mark_connector but
> object is from kmalloc-2048(361:anycast-healthchecker.service)
> ---
> 
> The kernel was fine and server was responsive.
> A coworker mentioned that it may come from
> https://github.com/torvalds/linux/blob/master/fs/notify/mark.c#L160
> and commit
> 08991e83b728 ("fsnotify: Free fsnotify_mark_connector when there is no mark
> attached") arrived with 4.12-rc1 may be the cause of it.
> 
> I am wondering if it is related to the issue I reported
> https://lkml.org/lkml/2018/4/16/506. But, that issue causes the whole server to
> crash, which is not the case for above kernel dump.
> 
> 
> Cheers,
> Pavlos
> 


-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR