On Mon, Sep 07, 2020 at 08:00:55PM +0200, Gerald Schaefer wrote: > This is v2 of an RFC previously discussed here: > https://lore.kernel.org/lkml/20200828140314.8556-1-gerald.schaefer@xxxxxxxxxxxxx/ > > Patch 1 is a fix for a regression in gup_fast on s390, after our conversion > to common gup_fast code. It will introduce special helper functions > pXd_addr_end_folded(), which have to be used in places where pagetable walk > is done w/o lock and with READ_ONCE, so currently only in gup_fast. > > Patch 2 is an attempt to make that more generic, i.e. change pXd_addr_end() > themselves by adding an extra pXd value parameter. That was suggested by > Jason during v1 discussion, because he is already thinking of some other > places where he might want to switch to the READ_ONCE logic for pagetable > walks. In general, that would be the cleanest / safest solution, but there > is some impact on other architectures and common code, hence the new and > greatly enlarged recipient list. > > Patch 3 is a "nice to have" add-on, which makes pXd_addr_end() inline > functions instead of #defines, so that we get some type checking for the > new pXd value parameter. > > Not sure about Fixes/stable tags for the generic solution. Only patch 1 > fixes a real bug on s390, and has Fixes/stable tags. Patches 2 + 3 might > still be nice to have in stable, to ease future backports, but I guess > "nice to have" does not really qualify for stable backports. I also think that adding pXd parameter to pXd_addr_end() is a cleaner way and with this patch 1 is not really required. I would even merge patches 2 and 3 into a single patch and use only it as the fix. [ /me apologises to stable@ team :-) ] > Changes in v2: > - Pick option 2 from v1 discussion (pXd_addr_end_folded helpers) > - Add patch 2 + 3 for more generic approach > > Alexander Gordeev (3): > mm/gup: fix gup_fast with dynamic page table folding > mm: make pXd_addr_end() functions page-table entry aware > mm: make generic pXd_addr_end() macros inline functions > > arch/arm/include/asm/pgtable-2level.h | 2 +- > arch/arm/mm/idmap.c | 6 ++-- > arch/arm/mm/mmu.c | 8 ++--- > arch/arm64/kernel/hibernate.c | 16 +++++---- > arch/arm64/kvm/mmu.c | 16 ++++----- > arch/arm64/mm/kasan_init.c | 8 ++--- > arch/arm64/mm/mmu.c | 25 +++++++------- > arch/powerpc/mm/book3s64/radix_pgtable.c | 7 ++-- > arch/powerpc/mm/hugetlbpage.c | 6 ++-- > arch/s390/include/asm/pgtable.h | 42 ++++++++++++++++++++++++ > arch/s390/mm/page-states.c | 8 ++--- > arch/s390/mm/pageattr.c | 8 ++--- > arch/s390/mm/vmem.c | 8 ++--- > arch/sparc/mm/hugetlbpage.c | 6 ++-- > arch/um/kernel/tlb.c | 8 ++--- > arch/x86/mm/init_64.c | 15 ++++----- > arch/x86/mm/kasan_init_64.c | 16 ++++----- > include/asm-generic/pgtable-nop4d.h | 2 +- > include/asm-generic/pgtable-nopmd.h | 2 +- > include/asm-generic/pgtable-nopud.h | 2 +- > include/linux/pgtable.h | 38 ++++++++++++--------- > mm/gup.c | 8 ++--- > mm/ioremap.c | 8 ++--- > mm/kasan/init.c | 17 +++++----- > mm/madvise.c | 4 +-- > mm/memory.c | 40 +++++++++++----------- > mm/mlock.c | 18 +++++++--- > mm/mprotect.c | 8 ++--- > mm/pagewalk.c | 8 ++--- > mm/swapfile.c | 8 ++--- > mm/vmalloc.c | 16 ++++----- > 31 files changed, 219 insertions(+), 165 deletions(-) > > -- > 2.17.1 > -- Sincerely yours, Mike.
