Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753084AbdLEQCl (ORCPT ); Tue, 5 Dec 2017 11:02:41 -0500 Received: from mail-qt0-f195.google.com ([209.85.216.195]:42165 "EHLO mail-qt0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752611AbdLEQCg (ORCPT ); Tue, 5 Dec 2017 11:02:36 -0500 X-Google-Smtp-Source: AGs4zMYYjZFGVSOeiZ8FL9s2ufEG2ahxp7nwGzSs0gu4rVSscdwCmxXOsfY9/i9bHAPo71zm/43+2QN0kf42P3cjn4U= MIME-Version: 1.0 From: Geert Uytterhoeven Date: Tue, 5 Dec 2017 17:02:35 +0100 X-Google-Sender-Auth: diiEfrn2ql6iKjwVXZOGjv1BLSg Message-ID: Subject: NFS crash, hashed pointers in backtrace To: Trond Myklebust , Anna Schumaker Cc: "Tobin C. Harding" , "open list:NFS, SUNRPC, AND..." , "linux-kernel@vger.kernel.org" , Linux-Renesas Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3182 Lines: 64 During a failed write to a virtual sysfs file (root fs is NFS), I got: Unable to handle kernel NULL pointer dereference at virtual address 00000020 pgd = c448bb15 [00000020] *pgd=69c9c003, *pmd=69d55003, *pte=00000000 Internal error: Oops: 207 [#1] SMP ARM Modules linked in: CPU: 0 PID: 1230 Comm: rs:main Q:Reg Not tainted 4.15.0-rc2-koelsch-01160-gd389a154c640caab-dirty #3752 Hardware name: Generic R-Car Gen2 (Flattened Device Tree) task: 4a3bb6d2 task.stack: fd0c00bd PC is at nfs_flush_incompatible+0x54/0xf8 LR is at _raw_spin_unlock+0x8/0x24 pc : [] lr : [] psr: 600c0013 sp : eab25e40 ip : 00000000 fp : eb9dc760 r10: ea4a1d94 r9 : 00000c20 r8 : eb9dc760 r7 : ea933840 r6 : eab24000 r5 : 00000000 r4 : 00000000 r3 : 00000000 r2 : ea933840 r1 : ea9d0900 r0 : e9d9fe40 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user Control: 30c5387d Table: 6aa37440 DAC: fffffffd Process rs:main Q:Reg (pid: 1230, stack limit = 0xab6fd568) Stack: (0xeab25e40 to 0xeab26000) 5e40: 00000000 00000000 00000ab9 0000660a eaaaea00 c03b098c 00000000 00000000 5e60: eab25f10 ea4a1d94 00000167 00000547 eab24000 eab24000 c081536c c02a646c 5e80: 00000167 00000000 eab25ea0 eab25ea4 0660aab9 00000000 eaaaea00 00000ab9 5ea0: eb9dc760 c028662c 00000000 ea4a1c98 eab25f28 eaaaea00 e9c56000 eab25f10 5ec0: eab24000 00000000 b5a1c8d0 c03b0c74 00000001 00000001 0009a6f0 c02880f8 5ee0: ffffffff eaaaea00 00000002 00000000 eab25f88 00000167 eab24000 c02eb0e0 5f00: 00000167 00000000 b5a1c8d0 00000167 00000001 00000000 00000167 eab25f08 5f20: 00000001 40000002 eaaaea00 00000000 0660aab9 00000000 00000000 00000000 5f40: 00000002 00000000 00000167 eaaaea00 eab25f88 b5a1c8d0 c0207044 c02eb280 5f60: eaaaea00 b5a1c8d0 00000167 eaaaea00 eaaaea03 00000167 b5a1c8d0 c0207044 5f80: eab24000 c02eb400 0660aab9 00000000 00000167 00000167 00000000 b5a1c710 5fa0: 00000004 c0206e60 00000167 00000000 00000005 b5a1c8d0 00000167 0007d000 5fc0: 00000167 00000000 b5a1c710 00000004 b58fe91c 00069be4 000998a0 b5a1c8d0 5fe0: 00000000 b58fe4d0 b6f3c4e9 b6f3c4f0 800c0030 00000005 00000000 00000000 [] (nfs_flush_incompatible) from [] (nfs_write_begin+0x50/0x208) [] (nfs_write_begin) from [] (generic_perform_write+0xc0/0x1ac) [] (generic_perform_write) from [] (nfs_file_write+0x130/0x254) [] (nfs_file_write) from [] (__vfs_write+0xf0/0x11c) [] (__vfs_write) from [] (vfs_write+0xb8/0x144) [] (vfs_write) from [] (SyS_write+0x40/0x80) [] (SyS_write) from [] (ret_fast_syscall+0x0/0x4c) Code: 13a04001 1a00000a e590300c e5971020 (e593c020) ---[ end trace 7dc43d92647b9bd9 ]--- Unfortunately, due to the%p hashing, I no longer know which values I can trust... Any clues? Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds