panic: Memory modified after free

[Yuri Pankov]

On Tue, Oct 8, 2019, at 10:12 AM, Andriy Gapon wrote:
> On 08/10/2019 03:39, Yuri Pankov wrote:
> > (posting to fs@ as backtrace suggests zfs)
> > 
> > Started seeing the following panic (sometimes reproducible, so can't point specific revision or time range) untaring an archive over ssh into my home directory on zfs:
> > 
> > panic: Memory modified after free 0xfffff80404cff000(4096) val=dead40de @ 0xfffff80404cff694
> > 
> > cpuid = 4
> > time = 1570493241
> > KDB: stack backtrace:
> > db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe00df912650
> > vpanic() at vpanic+0x19d/frame 0xfffffe00df9126a0
> > panic() at panic+0x43/frame 0xfffffe00df912700
> > trash_ctor() at trash_ctor+0x49/frame 0xfffffe00df912710
> > uma_zalloc_arg() at uma_zalloc_arg+0xa24/frame 0xfffffe00df9127a0
> > abd_alloc() at abd_alloc+0x152/frame 0xfffffe00df9127f0
> > arc_hdr_alloc_pabd() at arc_hdr_alloc_pabd+0x166/frame 0xfffffe00df912820
> > arc_write_ready() at arc_write_ready+0x463/frame 0xfffffe00df912860
> > zio_ready() at zio_ready+0xde/frame 0xfffffe00df9128a0
> > zio_execute() at zio_execute+0x17c/frame 0xfffffe00df9128e0
> > taskqueue_run_locked() at taskqueue_run_locked+0x10c/frame 0xfffffe00df912940
> > taskqueue_thread_loop() at taskqueue_thread_loop+0x88/frame 0xfffffe00df912970
> > fork_exit() at fork_exit+0x84/frame 0xfffffe00df9129b0
> > fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe00df9129b0
> > --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
> > 
> > Full text dump is at https://people.freebsd.org/~yuripv/core.txt.0.
> > 
> > Real problem or failing hardware (memory?)?
> 
> Given a single bit difference between 0xdead40de and 0xdeadc0de, it can be
> either.  If the memory is not ECC, then I would assume a hardware problem first.

Thank you.  Laptop with non-ECC memory, which started showing those bit flips after several memtest86 runs (it didn't previously).  Sorry for the noise!