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Date: Wed, 14 Aug 2013 18:44:26 +0200 From: Toralf Förster <toralf.foerster@....de> To: "J. Bruce Fields" <bfields@...ldses.org> CC: Jan Kara <jack@...e.cz>, Linux NFS mailing list <linux-nfs@...r.kernel.org>, "user-mode-linux-devel@...ts.sourceforge.net" <user-mode-linux-devel@...ts.sourceforge.net>, linux-ext4@...r.kernel.org, Linux Kernel <linux-kernel@...r.kernel.org>, "J. Bruce Fields" <bfields@...hat.com> Subject: Re: Issues with a rather unusual configured NFS server On 08/13/2013 11:53 PM, J. Bruce Fields wrote: > On Mon, Aug 12, 2013 at 04:36:40PM +0200, Jan Kara wrote: >> On Sun 11-08-13 11:48:49, Toralf Förster wrote: >>> so that the server either crashes (if it is a user mode linux image) or at least its reboot functionality got broken >>> - if the NFS server is hammered with scary NFS calls using a fuzzy tool running at a remote NFS client under a non-privileged user id. >>> >>> It can re reproduced, if >>> - the NFS share is an EXT3 or EXT4 directory >>> - and it is created at file located at tempfs and mounted via loop device >>> - and the NFS server is forced to umount the NFS share >>> - and the server forced to restart the NSF service afterwards >>> - and trinity is used >>> >>> I could find a scenario for an automated bisect. 2 times it brought this commit >>> commit 68a3396178e6688ad7367202cdf0af8ed03c8727 >>> Author: J. Bruce Fields <bfields@...hat.com> >>> Date: Thu Mar 21 11:21:50 2013 -0400 >>> >>> nfsd4: shut down more of delegation earlier > > Thanks for the report. I think I see the problem--after this commit > nfs4_set_delegation() failures result in nfs4_put_delegation being > called, but nfs4_put_delegation doesn't free the nfs4_file that has > already been set by alloc_init_deleg(). > > Let me think about how to fix that.... > > --b. > >> Added Bruce to CC. >> >>> to be the one after which the user mode linux server crashes with a back trace like this: >>> >>> >>> $ cat /mnt/ramdisk/bt.v3.11-rc4-172-g8ae3f1d >>> [New LWP 14025] >>> Core was generated by `/home/tfoerste/devel/linux/linux earlyprintk ubda=/home/tfoerste/virtual/uml/tr'. >>> Program terminated with signal 6, Aborted. >>> #0 0xb77ef424 in __kernel_vsyscall () >>> #0 0xb77ef424 in __kernel_vsyscall () >>> #1 0x083a33c5 in kill () >>> #2 0x0807163d in uml_abort () at arch/um/os-Linux/util.c:93 >>> #3 0x08071925 in os_dump_core () at arch/um/os-Linux/util.c:138 >>> #4 0x080613a7 in panic_exit (self=0x85a1518 <panic_exit_notifier>, unused1=0, unused2=0x85d6ce0 <buf.15904>) at arch/um/kernel/um_arch.c:240 >>> #5 0x0809a3b8 in notifier_call_chain (nl=0x0, val=0, v=0x85d6ce0 <buf.15904>, nr_to_call=-2, nr_calls=0x0) at kernel/notifier.c:93 >>> #6 0x0809a503 in __atomic_notifier_call_chain (nr_calls=<optimized out>, nr_to_call=<optimized out>, v=<optimized out>, val=<optimized out>, nh=<optimized out>) at kernel/notifier.c:182 >>> #7 atomic_notifier_call_chain (nh=0x85d6cc4 <panic_notifier_list>, val=0, v=0x85d6ce0 <buf.15904>) at kernel/notifier.c:191 >>> #8 0x08400ba8 in panic (fmt=0x0) at kernel/panic.c:128 >>> #9 0x0818edf4 in ext4_put_super (sb=0x4a042690) at fs/ext4/super.c:818 >>> #10 0x081010d2 in generic_shutdown_super (sb=0x4a042690) at fs/super.c:418 >>> #11 0x0810209a in kill_block_super (sb=0x0) at fs/super.c:1028 >>> #12 0x08100f6a in deactivate_locked_super (s=0x4a042690) at fs/super.c:299 >>> #13 0x08101001 in deactivate_super (s=0x4a042690) at fs/super.c:324 >>> #14 0x08118e0c in mntfree (mnt=<optimized out>) at fs/namespace.c:891 >>> #15 mntput_no_expire (mnt=0x0) at fs/namespace.c:929 >>> #16 0x0811a2f5 in SYSC_umount (flags=<optimized out>, name=<optimized out>) at fs/namespace.c:1335 >>> #17 SyS_umount (name=134541632, flags=0) at fs/namespace.c:1305 >>> #18 0x0811a369 in SYSC_oldumount (name=<optimized out>) at fs/namespace.c:1347 >>> #19 SyS_oldumount (name=134541632) at fs/namespace.c:1345 >>> #20 0x080618e2 in handle_syscall (r=0x49e919d4) at arch/um/kernel/skas/syscall.c:35 >>> #21 0x08073c0d in handle_trap (local_using_sysemu=<optimized out>, regs=<optimized out>, pid=<optimized out>) at arch/um/os-Linux/skas/process.c:198 >>> #22 userspace (regs=0x49e919d4) at arch/um/os-Linux/skas/process.c:431 >>> #23 0x0805e65c in fork_handler () at arch/um/kernel/process.c:160 >>> #24 0x00000000 in ?? () >>> >>> >>> >>> A real system however would not crash bug would give a kernel BUG as reported here: >>> http://article.gmane.org/gmane.comp.file-systems.ext4/38915 >> We have deleted inodes (regular files) in the orphan list during >> ext4_put_super(). My guess is that NFS is still holding some inode >> references to these inodes and thus inodes don't get deleted. So ext3/4 >> would be just a victim here. Just FWIW, EXT2 is not affected. >>> Furthermore the server won't be able any longer to reboot - it would hang >>> infinitely in the reboot phase. Just the magic sysrq keys still works >>> then. >> Well, this is likely because the filesystem cannot be shut down. >> >> Honza >> -- >> Jan Kara <jack@...e.cz> >> SUSE Labs, CR >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to majordomo@...r.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- MfG/Sincerely Toralf Förster pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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