As discussed on LKML http://marc.info/?i=54611D86.4040306%40de.ibm.com ACCESS_ONCE might fail with specific compiler for non-scalar accesses. Here is a set of patches to tackle that problem. (The first patch is already in kvm/next). The last patch will force ACCESS_ONCE to error-out if it is used on non-scalar accesses. I have cross-compiled the resulting kernel with defconfig for microblaze, m68k, alpha, s390,x86_64, i686, sparc, sparc64, mips, ia64, arm and arm64. So hopefully this patch set should be complete regarding the non-scalar accesses. (As Linus pointed out, accesses > word size are a problem on its own, but this patch set does not tackle this) The result is also available as 0d199efcfc9875b8de17bb4fe1d87a27bd39a172 on git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux.git ACCESS_ONCE Now: - It would be good to have the changes reviewed by component experts. - It would also be good if architecture maintainers could double check, that "kernel: Force ACCESS_ONCE to work only on scalar types" does not break anything beyond defconfig. - some comments about cc stable Thanks Christian ---------------------------------------------------------------- Christian Borntraeger (7): KVM: s390: Fix ipte locking mm: replace page table access via ACCESS_ONCE with barriers x86: Rework ACCESS_ONCE for spinlock code x86: Replace ACCESS_ONCE in gup with a barrier mips: Replace ACCESS_ONCE in gup with a barrier arm64: Replace ACCESS_ONCE for spinlock code with barriers kernel: Force ACCESS_ONCE to work only on scalar types arch/arm64/include/asm/spinlock.h | 7 +++++-- arch/mips/mm/gup.c | 6 ++++-- arch/s390/kvm/gaccess.c | 20 ++++++++++++++------ arch/x86/include/asm/spinlock.h | 14 +++++++++----- arch/x86/mm/gup.c | 7 +++++-- include/linux/compiler.h | 12 +++++++++++- mm/gup.c | 4 +++- mm/memory.c | 3 ++- mm/rmap.c | 3 ++- 9 files changed, 55 insertions(+), 21 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-x86_64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
