kern/78968: FreeBSD freezes on mbufs exhaustion (network interface independent)

[Ernie Smallis]

The following reply was made to PR kern/78968; it has been noted by GNATS.

From: Ernie Smallis <esmallis at stbernard.com>
To: bug-followup at freebsd.org, acid at gemius.pl
Cc:  
Subject: Re: kern/78968: FreeBSD freezes on mbufs exhaustion (network interface independent)
Date: Tue, 17 May 2005 11:41:47 -0700

 I am seeing this too:
 
 The fxp driver is receiving a return of ENOBUFS from m_getcl() (no surprise 
 there).  However, since there are no clusters available and the fxp driver 
 has frames to DMA from its FIFO; it keeps calling for clusters which never 
 happens successfully.  It appears the system is hung but; in fact, it is in a 
 tight loop.
 
 I believe BSD 4.x had a patch that fixed a panic for the exhaustion situation 
 since the code would be de-referencing a NULL pointer.  So, now we have a 
 test for NULL and the return of ENOBUFS.  That's one way of not seeing the 
 current problem ;-)
 
 Another way is to fix this.  The test for NULL is certainly appropriate 
 however, what happens next isn't.   I am looking to contact the relevant  
 committer(s) for a discussion as to how to resolve this problem.
 
 Regards,
 
 Ernie ;-)