diff options
| author | Heiko Carstens <hca@linux.ibm.com> | 2025-10-30 15:55:05 +0100 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2025-10-30 16:59:28 +0100 |
| commit | 64e2f60f355e556337fcffe80b9bcff1b22c9c42 (patch) | |
| tree | 868089b3d5a7afc3eaac27bda39dd536cd95aa26 | |
| parent | 07ad45e06b4039adf96882aefcb1d3299fb7c305 (diff) | |
s390: Disable ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
As reported by Luiz Capitulino enabling HVO on s390 leads to reproducible
crashes. The problem is that kernel page tables are modified without
flushing corresponding TLB entries.
Even if it looks like the empty flush_tlb_all() implementation on s390 is
the problem, it is actually a different problem: on s390 it is not allowed
to replace an active/valid page table entry with another valid page table
entry without the detour over an invalid entry. A direct replacement may
lead to random crashes and/or data corruption.
In order to invalidate an entry special instructions have to be used
(e.g. ipte or idte). Alternatively there are also special instructions
available which allow to replace a valid entry with a different valid
entry (e.g. crdte or cspg).
Given that the HVO code currently does not provide the hooks to allow for
an implementation which is compliant with the s390 architecture
requirements, disable ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP again, which is
basically a revert of the original patch which enabled it.
Reported-by: Luiz Capitulino <luizcap@redhat.com>
Closes: https://lore.kernel.org/all/20251028153930.37107-1-luizcap@redhat.com/
Fixes: 00a34d5a99c0 ("s390: select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP")
Cc: stable@vger.kernel.org
Tested-by: Luiz Capitulino <luizcap@redhat.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
| -rw-r--r-- | arch/s390/Kconfig | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index c4145672ca34..df22b10d9141 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -158,7 +158,6 @@ config S390 select ARCH_WANT_IRQS_OFF_ACTIVATE_MM select ARCH_WANT_KERNEL_PMD_MKWRITE select ARCH_WANT_LD_ORPHAN_WARN - select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP select ARCH_WANTS_THP_SWAP select BUILDTIME_TABLE_SORT select CLONE_BACKWARDS2 |