From owner-freebsd-bugs  Sat Jul 24 22:31:49 1999
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Date: Sat, 24 Jul 1999 22:30:01 -0700 (PDT)
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To: freebsd-bugs@FreeBSD.org
Cc: 
From: Tor.Egge@fast.no
Subject: Re: kern/12800: buffer leak in cluster_wbuild
Reply-To: Tor.Egge@fast.no
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The following reply was made to PR kern/12800; it has been noted by GNATS.

From: Tor.Egge@fast.no
To: tegge@not.fast.no
Cc: FreeBSD-gnats-submit@FreeBSD.ORG
Subject: Re: kern/12800: buffer leak in cluster_wbuild
Date: Sun, 25 Jul 1999 07:23:18 +0200

 With this patch installed, the problem with processes getting stuck in
 getblk disappeared.
 
 The spurious SIGBUSes were due to mmap allowing us to map memory
 completely after the end of the file.  When accessing the pages that
 weren't even partially backed by the file, the result was a SIGBUS.
 
 The coredump routines needs some more robustness against the program
 having performed incorrect mmap() operations.
 
 ---------------
 Index: vfs_cluster.c
 ===================================================================
 RCS file: /home/ncvs/src/sys/kern/vfs_cluster.c,v
 retrieving revision 1.87
 diff -u -r1.87 vfs_cluster.c
 --- vfs_cluster.c	1999/07/08 06:05:53	1.87
 +++ vfs_cluster.c	1999/07/25 05:08:52
 @@ -774,6 +774,20 @@
  					splx(s);
  					break;
  				}
 +				if (tbp->b_flags & B_VMIO) {
 +					vm_page_t m;
 +
 +					for (j = 0; 
 +					     j < tbp->b_npages; j += 1) {
 +						m = tbp->b_pages[j];
 +						if (m->flags & PG_BUSY) {
 +							BUF_UNLOCK(tbp);
 +							splx(s);
 +							goto finishcluster;
 +						}
 +					}
 +				}
 +					
  				/*
  				 * Ok, it's passed all the tests,
  				 * so remove it from the free list
 @@ -798,7 +812,7 @@
  					for (j = 0; j < tbp->b_npages; j += 1) {
  						m = tbp->b_pages[j];
  						if (m->flags & PG_BUSY)
 -							goto finishcluster;
 +							panic("cluster_wbuild: PG_BUSY: m=%p, tbp=%p\n", m, tbp);
  					}
  				}
  					
 
 ---------------
 


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