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[DragonFlyBSD - Bug #2249] deadlock under high i/o load (e.g. hammer reblock)

From: "Antonio M. Huete Jimenez via Redmine" <bugtracker-admin@xxxxxxxxxxxxxxxxxxxxx>
Date: Fri, 16 Dec 2011 12:48:21 -0800

Issue #2249 has been updated by Antonio M. Huete Jimenez.


It's indeed a deadlock. I'm experiencing that during 'hammer cleanup' also but on x86_64. Explanation from Matt:

21:21 <@dillon> the pageout daemon deadlock is because the hammer backend locks hammer inodes and the pageout
                daemon frontend can only detect locked vnodes
21:21 <@dillon> so the pageout daemon will happily lock a vnode and then issue the pageout request to the hammer
                backend and cause the hammer backend to get stuck on the inode (waiting for new memory)

It doesn't seem to have an easy solution.

Antonio Huete
Bug #2249: deadlock under high i/o load (e.g. hammer reblock)

Author: Rumko Rumko
Status: New
Priority: Normal
Target version: 

Almost latest master (last commit from upstream should be

Whenever nightly cron runs and a few minutes after hammer cleanup starts doing
it's job, the machine becomes mostly unresponsive (most processes and most ssh
connections stop responding, but strangely pf still continues doing it's job).

Fortunately debugging through serial console still worked, so the dump is
available at leaf:~rumko/crash/deadlock/*.0 .
Please do not CC me, since I already receive everything from these MLs.


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