Re: latest openjdk7 triggers kernel panic

On Thu, Dec 26, 2013 at 1:04 PM, Andriy Gapon <avg_at_freebsd.org> wrote:
>
> I am running FreeBSD based on the head from a few weeks ago, amd64.
>
> It seems that after a recent upgrade of openjdk7 I consistently get a kernel
> panic when a java process starts:
>
> panic: Bad entry start/end for new stack entry
> KDB: stack backtrace:
> db_trace_self_wrapper() at 0xffffffff803adc9b = db_trace_self_wrapper+0x2b/frame
> 0xfffffe02ba6fe6e0
> kdb_backtrace() at 0xffffffff805cbd79 = kdb_backtrace+0x39/frame 0xfffffe02ba6fe790
> panic() at 0xffffffff80597733 = panic+0x1a3/frame 0xfffffe02ba6fe810
> vm_map_stack() at 0xffffffff80719f2e = vm_map_stack+0x3ce/frame 0xfffffe02ba6fe8a0
> vm_mmap() at 0xffffffff8071c270 = vm_mmap+0x520/frame 0xfffffe02ba6fea30
> sys_mmap() at 0xffffffff8071bad3 = sys_mmap+0x303/frame 0xfffffe02ba6feaf0
> amd64_syscall() at 0xffffffff8074d0c8 = amd64_syscall+0x238/frame 0xfffffe02ba6febf0
> Xfast_syscall() at 0xffffffff80733e2b = Xfast_syscall+0xfb/frame 0xfffffe02ba6febf0
>
> Specifically, new_entry->end != top condition is true.
> new_entry->end is consistently greater than top by 3 pages.
>
> I suspect that java now does some hacky things with its stack and I suspect that
> vm_map_simplify_entry() call at the end of vm_map_insert() could be to blame.
> Although, the call is guarded by a check:
>
> 1290         /*
> 1291          * It may be possible to merge the new entry with the next and/or
> 1292          * previous entries.  However, due to MAP_STACK_* being a hack, a
> 1293          * panic can result from merging such entries.
> 1294          */
> 1295         if ((cow & (MAP_STACK_GROWS_DOWN | MAP_STACK_GROWS_UP)) == 0)
> 1296                 vm_map_simplify_entry(map, new_entry);
>
> But that check seems to be defeated by the fact that vm_map_stack() clears our
> the relevant bits after saving them locally:
>
> 3335         /*
> 3336          * The stack orientation is piggybacked with the cow argument.
> 3337          * Extract it into orient and mask the cow argument so that we
> 3338          * don't pass it around further.
> 3339          * NOTE: We explicitly allow bi-directional stacks.
> 3340          */
> 3341         orient = cow & (MAP_STACK_GROWS_DOWN|MAP_STACK_GROWS_UP);
> 3342         cow &= ~orient;


Hello,

FWIW,  I had a similar panic today on 9.2-RELEASE with a GENERIC kernel:
panic: Bad entry start/end for new stack entry
cpuid = 1
KDB: stack backtrace:
#0 0xffffffff80947986 at kdb_backtrace+0x66
#1 0xffffffff8090d9ae at panic+0x1ce
#2 0xffffffff80b81314 at vm_map_stack+0x274
#3 0xffffffff80b83584 at vm_mmap+0x674
#4 0xffffffff80b83d2f at sys_mmap+0x1cf
#5 0xffffffff80cf187a at amd64_syscall+0x5ea
#6 0xffffffff80cdbff7 at Xfast_syscall+0xf7

It looks like the box was compiling java related ports (java/jaxen and
devel/antlr) when it panic'ed.

Cheers,

Antoine