Messages in this thread | | | Date | Wed, 17 Jun 2015 13:45:27 +0200 | Subject | Re: mm: shmem_zero_setup skip security check and lockdep conflict with XFS | From | Morten Stevens <> |
| |
2015-06-15 8:09 GMT+02:00 Daniel Wagner <wagi@monom.org>: > On 06/14/2015 06:48 PM, Hugh Dickins wrote: >> It appears that, at some point last year, XFS made directory handling >> changes which bring it into lockdep conflict with shmem_zero_setup(): >> it is surprising that mmap() can clone an inode while holding mmap_sem, >> but that has been so for many years. >> >> Since those few lockdep traces that I've seen all implicated selinux, >> I'm hoping that we can use the __shmem_file_setup(,,,S_PRIVATE) which >> v3.13's commit c7277090927a ("security: shmem: implement kernel private >> shmem inodes") introduced to avoid LSM checks on kernel-internal inodes: >> the mmap("/dev/zero") cloned inode is indeed a kernel-internal detail. >> >> This also covers the !CONFIG_SHMEM use of ramfs to support /dev/zero >> (and MAP_SHARED|MAP_ANONYMOUS). I thought there were also drivers >> which cloned inode in mmap(), but if so, I cannot locate them now. >> >> Reported-and-tested-by: Prarit Bhargava <prarit@redhat.com> >> Reported-by: Daniel Wagner <wagi@monom.org> > > Reported-and-tested-by: Daniel Wagner <wagi@monom.org> > > Sorry for the long delay. It took me a while to figure out my original > setup. I could verify that this patch made the lockdep message go away > on 4.0-rc6 and also on 4.1-rc8.
Yes, it's also fixed for me after applying this patch to 4.1-rc8.
Best regards,
Morten
| |