247b6244d4
commit fffb5323780786c81ba005f8b8603d4a558aad28 upstream. With TDP MMU being the default now, access to mmu_rmaps_stat debugfs file causes following oops: BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 7 PID: 3185 Comm: cat Not tainted 5.16.0-rc4+ #204 RIP: 0010:pte_list_count+0x6/0x40 Call Trace: <TASK> ? kvm_mmu_rmaps_stat_show+0x15e/0x320 seq_read_iter+0x126/0x4b0 ? aa_file_perm+0x124/0x490 seq_read+0xf5/0x140 full_proxy_read+0x5c/0x80 vfs_read+0x9f/0x1a0 ksys_read+0x67/0xe0 __x64_sys_read+0x19/0x20 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fca6fc13912 Return early when rmaps are not present. Reported-by: Vasant Hegde <vasant.hegde@amd.com> Tested-by: Vasant Hegde <vasant.hegde@amd.com> Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220105040337.4234-1-nikunj@amd.com> Cc: stable@vger.kernel.org Fixes: 3bcd0662d66f ("KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file") Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.