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cp or rsync from NFS mount to local disk hangs when fsc is enabled

This document (7012769) is provided subject to the disclaimer at the end of this document.

Environment


SUSE Linux Enterprise Server 11 Service Pack 2

Situation

If fscache (fsc) is enabled for NFS the second 'cp' or 'rsync' after dropping the caches hangs. By copying/rsyncing a sparse file the hang can be reproduced without dropping the cache. Here's an example:

time cp -va /NFS/mount /tmp/ ; rm -rf /tmp/mount
time cp -va --sparse=always /NFS/mount /tmp/

or

time cp -va /NFS/mount /tmp/
echo 3 > /proc/sys/vm/drop_caches
sync
time cp -va /NFS/mount /tmp/


The cat /proc/<PID_of_cp>/stack shows:

[<ffffffff810efc89>] sleep_on_page_killable+0x9/0x40
[<ffffffff810efd56>] __lock_page_killable+0x96/0xd0
[<ffffffff810f0f47>] do_generic_file_read+0x227/0x490
[<ffffffff810f180c>] generic_file_aio_read+0xfc/0x260
[<ffffffffa0553cf1>] nfs_file_read+0xf1/0x140 [nfs]
[<ffffffff81150190>] do_sync_read+0xc0/0x100
[<ffffffff81150937>] vfs_read+0xc7/0x130
[<ffffffff81150aa3>] sys_read+0x53/0xa0
[<ffffffff8144ca12>] system_call_fastpath+0x16/0x1b
[<00007f052a61af00>] 0x7f052a61af00
[<ffffffffffffffff>] 0xffffffffffffffff

It seems that 'cp' is waiting to get access to a page that is already been locked but not been released. Any further access to the page hangs.

Resolution

The kernel update 3.0.80-0.5.1 released June 2013 includes the patch to resolve the problem. Please install the recommended update.

Cause


Additional Information


Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7012769
  • Creation Date: 02-Jul-2013
  • Modified Date:14-Oct-2022
    • SUSE Linux Enterprise Server

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