Re: panic in range_tree_seg64_compare()

On Thu, Aug 27, 2020 at 10:37 PM Yuri Pankov <ypankov_at_xsmail.com> wrote:
>
> Matthew Macy wrote:
> > On Thu, Aug 27, 2020 at 6:34 PM Yuri Pankov <ypankov_at_xsmail.com> wrote:
> >>
> >> Yet another issue I'm seeing after last update (currently running
> >> r364870), hit it 2 times today:
> >>
> >> Fatal trap 12: page fault while in kernel mode
> >> cpuid = 19; apic id = 0d
> >> fault virtual address   = 0xfffff819e2ecdc40
> >> fault code              = supervisor read data, page not present
> >> instruction pointer     = 0x20:0xffffffff8277fa64
> >> stack pointer           = 0x28:0xfffffe01f9ff2d90
> >> frame pointer           = 0x28:0xfffffe01f9ff2d90
> >> code segment            = base 0x0, limit 0xfffff, type 0x1b
> >>                           = DPL 0, pres 1, long 1, def32 0, gran 1
> >> processor eflags        = interrupt enabled, resume, IOPL = 0
> >> current process         = 48792 (blk-3:0-0)
> >> trap number             = 12
> >> panic: page fault
> >> cpuid = 19
> >> time = 1598577675
> >> KDB: stack backtrace:
> >> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
> >> 0xfffffe01f9ff2a40
> >> vpanic() at vpanic+0x182/frame 0xfffffe01f9ff2a90
> >> panic() at panic+0x43/frame 0xfffffe01f9ff2af0
> >> trap_fatal() at trap_fatal+0x387/frame 0xfffffe01f9ff2b50
> >> trap_pfault() at trap_pfault+0x97/frame 0xfffffe01f9ff2bb0
> >> trap() at trap+0x2ab/frame 0xfffffe01f9ff2cc0
> >> calltrap() at calltrap+0x8/frame 0xfffffe01f9ff2cc0
> >> --- trap 0xc, rip = 0xffffffff8277fa64, rsp = 0xfffffe01f9ff2d90, rbp =
> >> 0xfffffe01f9ff2d90 ---
> >> range_tree_seg64_compare() at range_tree_seg64_compare+0x4/frame
> >> 0xfffffe01f9ff2d90
> >> zfs_btree_find() at zfs_btree_find+0x1bd/frame 0xfffffe01f9ff2df0
> >> range_tree_find_impl() at range_tree_find_impl+0x6e/frame 0xfffffe01f9ff2e30
> >> range_tree_find() at range_tree_find+0x1c/frame 0xfffffe01f9ff2e70
> >> range_tree_contains() at range_tree_contains+0x9/frame 0xfffffe01f9ff2e80
> >> dnode_block_freed() at dnode_block_freed+0x11d/frame 0xfffffe01f9ff2eb0
> >> dbuf_read() at dbuf_read+0x70c/frame 0xfffffe01f9ff2fc0
> >> dmu_buf_hold_array_by_dnode() at dmu_buf_hold_array_by_dnode+0x164/frame
> >> 0xfffffe01f9ff3030
> >> dmu_read_impl() at dmu_read_impl+0xce/frame 0xfffffe01f9ff30c0
> >> dmu_read() at dmu_read+0x45/frame 0xfffffe01f9ff3100
> >> zvol_geom_bio_strategy() at zvol_geom_bio_strategy+0x2aa/frame
> >> 0xfffffe01f9ff3180
> >> g_io_request() at g_io_request+0x2df/frame 0xfffffe01f9ff31b0
> >> g_dev_strategy() at g_dev_strategy+0x155/frame 0xfffffe01f9ff31e0
> >> physio() at physio+0x4f8/frame 0xfffffe01f9ff3270
> >> devfs_read_f() at devfs_read_f+0xde/frame 0xfffffe01f9ff32d0
> >> dofileread() at dofileread+0x81/frame 0xfffffe01f9ff3320
> >> kern_preadv() at kern_preadv+0x62/frame 0xfffffe01f9ff3360
> >> sys_preadv() at sys_preadv+0x39/frame 0xfffffe01f9ff3390
> >> amd64_syscall() at amd64_syscall+0x140/frame 0xfffffe01f9ff34b0
> >> fast_syscall_common() at fast_syscall_common+0xf8/frame 0xfffffe01f9ff34b0
> >> --- syscall (289, FreeBSD ELF64, sys_preadv), rip = 0x8006fd89a, rsp =
> >> 0x7fffdfdfcf18, rbp = 0x7fffdfdfcfc0 ---
> >> Uptime: 4h13m43s
> >
> >
> >>
> >> Guessing on zvol_geom_bio_strategy(), it's volmode=dev zvol I'm using
> >> for bhyve VM.  Anything known?
> >
> > Not really. A reproduction scenario would be very helpful. This was
> > seen once by someone at iX - I committed some additional asserts to
> > the truenas tree, but haven't heard further.
> >
> > +++ b/module/zfs/dbuf.c
> > _at__at_ -3192,7 +3192,7 _at__at_
> > dbuf_dirty_leaf_with_existing_frontend(dbuf_dirty_state_t *dds)
> >                           * scheduled its write with its buffer, we must
> >                           * disassociate by replacing the frontend.
> >                           */
> > -                       ASSERT(db->db_state & (DB_READ|DB_PARTIAL));
> > +                       ASSERT3U(db->db_state, &, (DB_READ|DB_PARTIAL));
> >                          ASSERT3U(db->db_dirtycnt, ==, 1);
> >                          dbuf_dirty_set_data(dds);
> >                  } else {
> > _at__at_ -3238,18 +3238,24 _at__at_ dbuf_dirty_record_create_leaf(dbuf_dirty_state_t *dds)
> >
> >          dr = dbuf_dirty_record_create(dds);
> >
> > +       /*
> > +        * XXX - convert to ASSERT after dn_free_ranges fix
> > +        */
> > +       VERIFY(db->db_level == 0);
> > +       VERIFY(db->db_blkid != DMU_BONUS_BLKID);
>
> Can't find context for both chunks, there are simply no such functions
> in sys/contrib/openzfs/module/zfs/dbuf.c, and yes, note that I'm running
> the in-tree version.

Sorry. I forgot that this was against the cow fault avoidance changes.