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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.


SUSE Linux Enterprise Server 11 Service Pack 2


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/


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


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


Additional Information


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

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