From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Fri, 22 Jul 2011 20:55:27 +0000 (-0700)
Subject: Fix txg_sync_thread deadlock
X-Git-Url: https://git.camperquake.de/gitweb.cgi?a=commitdiff_plain;ds=sidebyside;h=beb982690293310b14a4835d3ffeb883ba03cc0a;hp=beb982690293310b14a4835d3ffeb883ba03cc0a;p=zfs.git

Fix txg_sync_thread deadlock

Update two kmem_alloc()'s in dbuf_dirty() to use KM_PUSHPAGE.
Because these functions are called from txg_sync_thread we
must ensure they don't reenter the zfs filesystem code via
the .writepage callback.  This would result in a deadlock.

This deadlock is rare and has only been observed once under
an abusive mmap() write workload.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
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