[DragonFlyBSD - Bug #2364] (In Progress) panic: lockmgr: locking against myself
Matthew Dillon via Redmine
bugtracker-admin at leaf.dragonflybsd.org
Thu Aug 16 17:06:11 PDT 2012
Issue #2364 has been updated by Matthew Dillon.
Status changed from New to In Progress
Here is a better test program, works for x86-64 or i386. The size of the file depends on how UFS was formatted. The file must be such that the last block is a fragment which covers less than a page. We then issue a write that hits that fragment. The bread() of the buffer brings in the VM page but the VM page's valid bits are not fully set. This then causes the copyin or copyout to fault, creating the double-lock.
* Must be one fragment less than a page. Typical UFS filesystems
* are configured 1K/8K or 2K/16K. Larger ones tend to be configured
* 2K/16K. Use 7168 for 1K/8K and 6144 for 2K/16K
* dd if=/dev/zero of=test bs=6144 count=1
* dd if=/dev/zero of=test bs=7168 count=1
main(int argc, char **argv)
int i0, i;
fd = open(argv, O_RDWR);
mmap_region = mmap(NULL, 16384 * 2,
fprintf(stderr, "%d %p\n", fd, mmap_region);
madvise(mmap_region, 16384 * 2, MADV_RANDOM);
madvise(mmap_region, 16384 * 2, MADV_INVAL);
mmap_region = 'b';
lseek(fd, 0, SEEK_SET);
n = write(fd, mmap_region, 4096+2048);
printf("write n=%zd\n", n);
munmap(mmap_region, 16384 * 2);
Bug #2364: panic: lockmgr: locking against myself
Author: John Marino
Status: In Progress
Assignee: Venkatesh Srinivas
This is an easily repeatable panic.
Edit a file with size > 4096 bytes using /usr/pkg/bin/heme, and save.
Seen on i386 on Virtualbox but already reproduced independently by vrinivas.
DragonFly a4d7a8c-DEVELOPMENT #4: Mon May 7 18:55:28 CEST 2012 root@:/usr/obj/usr/src/sys/GENERIC
core dump located in leaf ~marino/crash
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