#./shmns4
shmns4:
  One process creates and maps shm segments in multiple namespaces.
  The namespaces are replaced before unmapping the segments.
 1) unshare(0x8000000).
create a namespace, create 2 shm segments, do not map them.
 2) unshare(0x8000000).
[   71.444890] newseg(): shp ffff888003a84f00: shp->shm_nattch 0 ->shmfile ffff88800428f500.
[   71.448696] newseg(): shp ffff888003a84e00: shp->shm_nattch 0 ->shmfile ffff88800428f900.
 2) unshare(0x8000000).
[   71.453352] shm_may_destroy(): shp ffff888003a84e00: shp->shm_nattch 0.
[   71.455822] shm_may_destroy(): shp ffff888003a84f00: shp->shm_nattch 0.
[   71.460332] namespace ffff888003679400: in exit_ns.
[   71.461783] namespace ffff888003679400: end of exit_ns.
create a namespace, create 2 shm segments, do not map them, no auto-rm.
[   76.481527] newseg(): shp ffff888003a84f00: shp->shm_nattch 0 ->shmfile ffff88800428f800.
[   76.486162] newseg(): shp ffff888003a84e00: shp->shm_nattch 0 ->shmfile ffff88800428f900.
 2) unshare(0x8000000).
[   76.496480] namespace ffff888003679800: in exit_ns.
[   76.499758] do_shm_rmid(): shp ffff888003a84f00: shp->shm_nattch 0.
[   76.515934] do_shm_rmid(): shp ffff888003a84e00: shp->shm_nattch 0.
[   76.537126] namespace ffff888003679800: end of exit_ns.
create a namespace, create 2 shm segments, map them.
[   81.517464] newseg(): shp ffff888003a84e00: shp->shm_nattch 0 ->shmfile ffff88800428f800.
[   81.526964] do_shmat(): shp ffff888003a84e00: shp->shm_nattch 0.
[   81.531575] do_shmat(): shp ffff888003a84e00: get_ipc_ns().
[   81.542459] __shm_open(): before ++: shp ffff888003a84e00, sfd->file ffff88800428f800: shp->shm_nattch 1.
[   81.549390] do_shmat() before --: shp ffff888003a84e00: shp->shm_nattch 2.
[   81.554699] shm_may_destroy(): shp ffff888003a84e00: shp->shm_nattch 1.
[   81.560649] newseg(): shp ffff888003a84f00: shp->shm_nattch 0 ->shmfile ffff88800428f500.
[   81.564649] do_shmat(): shp ffff888003a84f00: shp->shm_nattch 0.
[   81.568681] do_shmat(): shp ffff888003a84f00: get_ipc_ns().
[   81.573865] __shm_open(): before ++: shp ffff888003a84f00, sfd->file ffff88800428f500: shp->shm_nattch 1.
[   81.576866] do_shmat() before --: shp ffff888003a84f00: shp->shm_nattch 2.
[   81.580494] shm_may_destroy(): shp ffff888003a84f00: shp->shm_nattch 1.
 2) unshare(0x8000000).
[   81.589648] shm_may_destroy(): shp ffff888003a84f00: shp->shm_nattch 1.
[   81.592431] shm_may_destroy(): shp ffff888003a84e00: shp->shm_nattch 1.
Once more: Create a namespace, create 2 shm segments, map them, no auto-rm.
[   86.609807] newseg(): shp ffff888003a84000: shp->shm_nattch 0 ->shmfile ffff888004023a00.
[   86.613978] do_shmat(): shp ffff888003a84000: shp->shm_nattch 0.
[   86.616616] do_shmat(): shp ffff888003a84000: get_ipc_ns().
[   86.621714] __shm_open(): before ++: shp ffff888003a84000, sfd->file ffff888004023a00: shp->shm_nattch 1.
[   86.625975] do_shmat() before --: shp ffff888003a84000: shp->shm_nattch 2.
[   86.629578] shm_may_destroy(): shp ffff888003a84000: shp->shm_nattch 1.
[   86.633766] newseg(): shp ffff888003a84100: shp->shm_nattch 0 ->shmfile ffff888004023e00.
[   86.639642] do_shmat(): shp ffff888003a84100: shp->shm_nattch 0.
[   86.643634] do_shmat(): shp ffff888003a84100: get_ipc_ns().
[   86.646951] __shm_open(): before ++: shp ffff888003a84100, sfd->file ffff888004023e00: shp->shm_nattch 1.
[   86.651648] do_shmat() before --: shp ffff888003a84100: shp->shm_nattch 2.
[   86.660527] shm_may_destroy(): shp ffff888003a84100: shp->shm_nattch 1.
Orphan namespace (switch back to parent namespace).
Before exit of child: 4 mappings exist in 2 namespaces.
[   91.750385] shm_close(): before --: shp ffff888003a84100: shp->shm_nattch 1.
[   91.755503] shm_may_destroy(): shp ffff888003a84100: shp->shm_nattch 0.
[   91.758710] shm_close(): before --: shp ffff888003a84000: shp->shm_nattch 1.
[   91.761828] shm_may_destroy(): shp ffff888003a84000: shp->shm_nattch 0.
[   91.764879] shm_close(): before --: shp ffff888003a84f00: shp->shm_nattch 1.
[   91.768248] shm_may_destroy(): shp ffff888003a84f00: shp->shm_nattch 0.
[   91.772642] shm_close(): before --: shp ffff888003a84e00: shp->shm_nattch 1.
[   91.776417] shm_may_destroy(): shp ffff888003a84e00: shp->shm_nattch 0.
[   91.790861] shm_release: file ffff88800428f800, put_ipc_ns().
[   91.796858] shm_release: file ffff88800428f500, put_ipc_ns().
[   91.805866] namespace ffff888003679400: in exit_ns.
[   91.808458] namespace ffff888003679400: end of exit_ns.
[   91.816613] shm_release: file ffff888004023a00, put_ipc_ns().
[   91.821392] shm_release: file ffff888004023e00, put_ipc_ns().
[   91.825715] namespace ffff888003679800: in exit_ns.
[   91.828811] do_shm_rmid(): shp ffff888003a84000: shp->shm_nattch 0.
[   91.832453] do_shm_rmid(): shp ffff888003a84100: shp->shm_nattch 0.
[   91.843841] namespace ffff888003679800: end of exit_ns.
parent:waitpid returned 285, status 0.
[  101.882842] namespace ffff888003679000: in exit_ns.
[  101.885707] namespace ffff888003679000: end of exit_ns.
#