panic in range_tree_seg64_compare()

[Matthew Macy]

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
@@ -3192,7 +3192,7 @@
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 {
@@ -3238,18 +3238,24 @@ 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);


Thanks.
-M