On Tue, May 20, 2014 at 10:21 AM, Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote: > On Mon, May 19, 2014 at 03:58:33PM -0700, Andy Lutomirski wrote: >> Using arch_vma_name to give special mappings a name is awkward. x86 >> currently implements it by comparing the start address of the vma to >> the expected address of the vdso. This requires tracking the start >> address of special mappings and is probably buggy if a special vma >> is split or moved. >> >> Improve _install_special_mapping to just name the vma directly. Use >> it to give the x86 vvar area a name, which should make CRIU's life >> easier. >> >> As a side effect, the vvar area will show up in core dumps. This >> could be considered weird and is fixable. Thoughts? >> >> Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> >> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> >> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx> > > Hi Andy, thanks a lot for this! I must confess I don't yet know how > would we deal with compat tasks but this is 'must have' mark which > allow us to detect vvar area! Out of curiosity, how does CRIU currently handle checkpointing a restored task? In current kernels, the "[vdso]" name in maps goes away after mremapping the vdso. I suspect that you'll need kernel changes for compat tasks, since I think that mremapping the vdso on any reasonably modern hardware in a 32-bit task will cause sigreturn to blow up. This could be fixed by making mremap magical, although adding a new prctl or arch_prctl to reliably move the vdso might be a better bet. --Andy -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>