Messages in this thread | | | Date | Mon, 15 Jun 2015 08:09:16 +0200 | From | Daniel Wagner <> | Subject | Re: mm: shmem_zero_setup skip security check and lockdep conflict with XFS |
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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.
For the record: SELinux needs to be enabled triggering it.
cheers, daniel
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