| Message ID | 20210120173612.20913-1-will@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Create 'old' ptes for faultaround mappings on arm64 with hardware access flag | expand |
On Wed, Jan 20, 2021 at 05:36:04PM +0000, Will Deacon wrote: > Hi all, > > This is version four of the patches I previously posted here: > > v1: https://lore.kernel.org/r/20201209163950.8494-1-will@kernel.org > v2: https://lore.kernel.org/r/20210108171517.5290-1-will@kernel.org > v3: https://lore.kernel.org/r/20210114175934.13070-1-will@kernel.org > > The patches allow architectures to opt-in at runtime for faultaround > mappings to be created as 'old' instead of 'young'. Although there have > been previous attempts at this, they failed either because the decision > was deferred to userspace [1] or because it was done unconditionally and > shown to regress benchmarks for particular architectures [2]. > > The big change since v3 is that the immutable fields of 'struct vm_fault' > now live in a 'const' anonymous struct. Although Clang will silently > accept modifications to these fields [3], GCC emits an error. The > resulting diffstat is _considerably_ more manageable with this approach. The only changes I have pending against this series are cosmetic (commit logs). Can I go ahead and queue this in the arm64 tree so that it can sit in linux-next for a bit? (positive or negative feedback appreciated!). Thanks, Will
On Tue, 26 Jan 2021, Will Deacon wrote: > On Wed, Jan 20, 2021 at 05:36:04PM +0000, Will Deacon wrote: > > Hi all, > > > > This is version four of the patches I previously posted here: > > > > v1: https://lore.kernel.org/r/20201209163950.8494-1-will@kernel.org > > v2: https://lore.kernel.org/r/20210108171517.5290-1-will@kernel.org > > v3: https://lore.kernel.org/r/20210114175934.13070-1-will@kernel.org > > > > The patches allow architectures to opt-in at runtime for faultaround > > mappings to be created as 'old' instead of 'young'. Although there have > > been previous attempts at this, they failed either because the decision > > was deferred to userspace [1] or because it was done unconditionally and > > shown to regress benchmarks for particular architectures [2]. > > > > The big change since v3 is that the immutable fields of 'struct vm_fault' > > now live in a 'const' anonymous struct. Although Clang will silently > > accept modifications to these fields [3], GCC emits an error. The > > resulting diffstat is _considerably_ more manageable with this approach. > > The only changes I have pending against this series are cosmetic (commit > logs). Can I go ahead and queue this in the arm64 tree so that it can sit > in linux-next for a bit? (positive or negative feedback appreciated!). That would be fine by me: I ran v3 on rc3, then the nicer smaller v4 on rc4, and saw no problems when running either of them (x86_64 only). Hugh
On Tue, Jan 26, 2021 at 03:28:22PM -0800, Hugh Dickins wrote: > On Tue, 26 Jan 2021, Will Deacon wrote: > > On Wed, Jan 20, 2021 at 05:36:04PM +0000, Will Deacon wrote: > > > Hi all, > > > > > > This is version four of the patches I previously posted here: > > > > > > v1: https://lore.kernel.org/r/20201209163950.8494-1-will@kernel.org > > > v2: https://lore.kernel.org/r/20210108171517.5290-1-will@kernel.org > > > v3: https://lore.kernel.org/r/20210114175934.13070-1-will@kernel.org > > > > > > The patches allow architectures to opt-in at runtime for faultaround > > > mappings to be created as 'old' instead of 'young'. Although there have > > > been previous attempts at this, they failed either because the decision > > > was deferred to userspace [1] or because it was done unconditionally and > > > shown to regress benchmarks for particular architectures [2]. > > > > > > The big change since v3 is that the immutable fields of 'struct vm_fault' > > > now live in a 'const' anonymous struct. Although Clang will silently > > > accept modifications to these fields [3], GCC emits an error. The > > > resulting diffstat is _considerably_ more manageable with this approach. > > > > The only changes I have pending against this series are cosmetic (commit > > logs). Can I go ahead and queue this in the arm64 tree so that it can sit > > in linux-next for a bit? (positive or negative feedback appreciated!). > > That would be fine by me: I ran v3 on rc3, then the nicer smaller v4 > on rc4, and saw no problems when running either of them (x86_64 only). Thanks, Hugh. I'll stick these into -next later today and we'll see how we get on. Will
Hi all, This is version four of the patches I previously posted here: v1: https://lore.kernel.org/r/20201209163950.8494-1-will@kernel.org v2: https://lore.kernel.org/r/20210108171517.5290-1-will@kernel.org v3: https://lore.kernel.org/r/20210114175934.13070-1-will@kernel.org The patches allow architectures to opt-in at runtime for faultaround mappings to be created as 'old' instead of 'young'. Although there have been previous attempts at this, they failed either because the decision was deferred to userspace [1] or because it was done unconditionally and shown to regress benchmarks for particular architectures [2]. The big change since v3 is that the immutable fields of 'struct vm_fault' now live in a 'const' anonymous struct. Although Clang will silently accept modifications to these fields [3], GCC emits an error. The resulting diffstat is _considerably_ more manageable with this approach. As before, I've also updated this branch: https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=faultaround Cheers, Will [1] https://www.spinics.net/lists/linux-mm/msg143831.html [2] 315d09bf30c2 ("Revert "mm: make faultaround produce old ptes"") [3] https://bugs.llvm.org/show_bug.cgi?id=48755 Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Jan Kara <jack@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: <kernel-team@android.com> --->8 Kirill A. Shutemov (1): mm: Cleanup faultaround and finish_fault() codepaths Will Deacon (7): mm: Allow architectures to request 'old' entries when prefaulting arm64: mm: Implement arch_wants_old_prefaulted_pte() mm: Move immutable fields of 'struct vm_fault' into anonymous struct mm: Pass 'address' to map to do_set_pte() and drop FAULT_FLAG_PREFAULT mm: Avoid modifying vmf.address in __collapse_huge_page_swapin() mm: Use static initialisers for immutable fields of 'struct vm_fault' mm: Mark anonymous struct field of 'struct vm_fault' as 'const' arch/arm64/include/asm/pgtable.h | 12 +- fs/xfs/xfs_file.c | 6 +- include/linux/mm.h | 25 ++-- include/linux/pgtable.h | 11 ++ mm/filemap.c | 178 ++++++++++++++++++------ mm/khugepaged.c | 37 +++-- mm/memory.c | 223 +++++++++++-------------------- mm/shmem.c | 6 +- mm/swapfile.c | 11 +- 9 files changed, 280 insertions(+), 229 deletions(-)