I don't have a precise number, but my impression is that it's frequent enough.
Here is some quick sampling for such cases. Each group corresponds to
a single build:
run #0: crashed: general protection fault in sctp_assoc_rwnd_increase
run #1: crashed: general protection fault in sctp_ulpevent_free
run #2: crashed: general protection fault in sctp_assoc_rwnd_increase
run #3: crashed: general protection fault in sctp_assoc_rwnd_increase
run #4: crashed: general protection fault in sctp_assoc_rwnd_increase
run #5: crashed: general protection fault in sctp_assoc_rwnd_increase
run #6: crashed: general protection fault in sctp_assoc_rwnd_increase
run #7: crashed: general protection fault in sctp_assoc_rwnd_increase
run #0: crashed: general protection fault in sctp_assoc_rwnd_increase
run #1: crashed: general protection fault in sctp_assoc_rwnd_increase
run #2: crashed: general protection fault in sctp_assoc_rwnd_increase
run #3: crashed: general protection fault in sctp_assoc_rwnd_increase
run #4: crashed: general protection fault in corrupted
run #5: crashed: general protection fault in sctp_assoc_rwnd_increase
run #6: crashed: general protection fault in sctp_assoc_rwnd_increase
run #7: crashed: general protection fault in corrupted
run #0: crashed: INFO: rcu detected stall in corrupted
run #1: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #2: crashed: INFO: rcu detected stall in sys_sendfile64
run #3: crashed: INFO: rcu detected stall in corrupted
run #4: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #5: crashed: INFO: rcu detected stall in corrupted
run #6: crashed: INFO: rcu detected stall in corrupted
run #7: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #8: crashed: INFO: rcu detected stall in sys_sendfile64
run #9: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #0: crashed: INFO: rcu detected stall in sys_sendfile64
run #1: crashed: INFO: rcu detected stall in corrupted
run #2: crashed: INFO: rcu detected stall in corrupted
run #3: crashed: INFO: rcu detected stall in sys_sendfile64
run #4: crashed: INFO: rcu detected stall in corrupted
run #5: crashed: INFO: rcu detected stall in corrupted
run #6: crashed: INFO: rcu detected stall in corrupted
run #7: crashed: INFO: rcu detected stall in corrupted
run #8: crashed: INFO: rcu detected stall in sys_sendfile64
run #9: crashed: INFO: rcu detected stall in corrupted
run #0: crashed: INFO: rcu detected stall in rw_verify_area
run #1: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #2: crashed: INFO: rcu detected stall in corrupted
run #3: crashed: INFO: rcu detected stall in corrupted
run #4: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #5: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #6: crashed: INFO: rcu detected stall in corrupted
run #7: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #8: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #9: crashed: INFO: rcu detected stall in rw_verify_area
run #0: crashed: INFO: rcu detected stall in ext4_file_write_iter
run #1: crashed: INFO: rcu detected stall in corrupted
run #2: crashed: INFO: rcu detected stall in sys_sendfile64
run #3: crashed: INFO: rcu detected stall in sys_sendfile64
run #4: crashed: INFO: rcu detected stall in corrupted
run #5: crashed: INFO: rcu detected stall in sys_sendfile64
run #6: crashed: INFO: rcu detected stall in sys_sendfile64
run #7: crashed: INFO: rcu detected stall in corrupted
run #8: crashed: INFO: rcu detected stall in corrupted
run #9: crashed: INFO: rcu detected stall in sys_sendfile64
run #0: crashed: KASAN: use-after-free Read in link_path_walk
run #1: crashed: KASAN: use-after-free Read in link_path_walk
run #2: crashed: KASAN: use-after-free Read in trailing_symlink
run #3: crashed: KASAN: use-after-free Read in trailing_symlink
run #4: crashed: KASAN: use-after-free Read in trailing_symlink
run #5: crashed: KASAN: use-after-free Read in link_path_walk
run #6: crashed: KASAN: use-after-free Read in link_path_walk
run #7: crashed: KASAN: use-after-free Read in link_path_walk
run #8: crashed: KASAN: use-after-free Read in trailing_symlink
run #9: crashed: KASAN: use-after-free Read in trailing_symlink
run #0: crashed: BUG: unable to handle kernel NULL pointer dereference
in mrvl_setup
run #1: crashed: BUG: unable to handle kernel NULL pointer dereference
in mrvl_setup
run #2: crashed: BUG: unable to handle kernel NULL pointer dereference
in mrvl_setup
run #3: crashed: BUG: unable to handle kernel NULL pointer dereference
in mrvl_setup
run #4: crashed: WARNING: ODEBUG bug in corrupted
run #5: crashed: BUG: unable to handle kernel NULL pointer dereference
in mrvl_setup
run #6: crashed: BUG: unable to handle kernel NULL pointer dereference
in mrvl_setup
run #7: crashed: BUG: unable to handle kernel NULL pointer dereference
in mrvl_setup
run #8: crashed: BUG: unable to handle kernel NULL pointer dereference
in mrvl_setup
run #9: crashed: BUG: unable to handle kernel NULL pointer dereference
in mrvl_setup
run #0: crashed: KASAN: use-after-free Read in delayed_uprobe_remove
run #1: crashed: KASAN: use-after-free Read in delayed_uprobe_remove
run #2: crashed: general protection fault in delayed_uprobe_remove
run #3: crashed: KASAN: use-after-free Read in delayed_uprobe_remove
run #4: crashed: general protection fault in delayed_uprobe_remove
run #5: crashed: KASAN: use-after-free Read in delayed_uprobe_remove
run #6: OK
run #7: OK
run #8: OK
run #9: OK
run #0: crashed: general protection fault in delayed_uprobe_remove
run #1: crashed: KASAN: use-after-free Read in delayed_uprobe_remove
run #2: crashed: KASAN: use-after-free Read in delayed_uprobe_remove
run #3: crashed: KASAN: use-after-free Read in delayed_uprobe_remove
run #4: crashed: general protection fault in delayed_uprobe_remove
run #5: crashed: KASAN: use-after-free Read in delayed_uprobe_remove
run #6: OK
run #7: OK
run #8: OK
run #9: OK
run #0: crashed: KASAN: use-after-free Read in fuse_dev_do_read
run #1: crashed: WARNING in request_end
run #2: crashed: KASAN: use-after-free Read in fuse_dev_do_read
run #3: OK
run #4: OK
run #0: crashed: KASAN: slab-out-of-bounds Read in __ip_append_data
run #1: crashed: inconsistent lock state in rhashtable_walk_enter
run #2: crashed: inconsistent lock state in rhashtable_walk_enter
run #3: crashed: inconsistent lock state in rhashtable_walk_enter
run #4: crashed: inconsistent lock state in rhashtable_walk_enter
run #5: crashed: inconsistent lock state in rhashtable_walk_enter
run #6: crashed: inconsistent lock state in rhashtable_walk_enter
run #7: crashed: kernel BUG at arch/x86/mm/physaddr.c:LINE!
run #8: crashed: inconsistent lock state in rhashtable_walk_enter
run #9: crashed: inconsistent lock state in rhashtable_walk_enter
run #0: crashed: kernel BUG at arch/x86/mm/physaddr.c:LINE!
run #1: crashed: inconsistent lock state in rhashtable_walk_enter
run #2: crashed: inconsistent lock state in rhashtable_walk_enter
run #3: crashed: inconsistent lock state in rhashtable_walk_enter
run #4: crashed: inconsistent lock state in rhashtable_walk_enter
run #5: crashed: kernel BUG at arch/x86/mm/physaddr.c:LINE!
run #6: crashed: inconsistent lock state in rhashtable_walk_enter
run #7: crashed: kernel BUG at arch/x86/mm/physaddr.c:LINE!
run #8: crashed: inconsistent lock state in rhashtable_walk_enter
run #9: crashed: inconsistent lock state in rhashtable_walk_enter
run #0: crashed: KASAN: use-after-free Read in __vb2_perform_fileio
run #1: crashed: KASAN: use-after-free Write in __vb2_cleanup_fileio
run #2: crashed: KASAN: use-after-free Read in __vb2_perform_fileio
run #3: crashed: KASAN: use-after-free Read in __vb2_perform_fileio
run #4: crashed: INFO: task hung in vivid_stop_generating_vid_cap
run #5: crashed: INFO: task hung in vivid_stop_generating_vid_cap
run #6: crashed: INFO: task hung in vivid_stop_generating_vid_cap
run #7: crashed: INFO: task hung in vivid_stop_generating_vid_cap
run #8: crashed: INFO: task hung in vivid_stop_generating_vid_cap
run #9: crashed: INFO: task hung in vivid_stop_generating_vid_cap