Re: [PATCH v4 4/7] mm: replace vma->vm_flags direct modifications with modifier calls
From: Suren Baghdasaryan <surenb@google.com>
Date: 2023-01-31 18:54:39
Also in:
linux-mm, linuxppc-dev, lkml
On Tue, Jan 31, 2023 at 12:32 AM Hyeonggon Yoo [off-list ref] wrote:
On Thu, Jan 26, 2023 at 11:37:49AM -0800, Suren Baghdasaryan wrote:quoted
Replace direct modifications to vma->vm_flags with calls to modifier functions to be able to track flag changes and to keep vma locking correctness. Signed-off-by: Suren Baghdasaryan <surenb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <redacted> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Acked-by: Sebastian Reichel <redacted> --- arch/arm/kernel/process.c | 2 +- arch/ia64/mm/init.c | 8 ++++---- arch/loongarch/include/asm/tlb.h | 2 +- arch/powerpc/kvm/book3s_xive_native.c | 2 +- arch/powerpc/mm/book3s64/subpage_prot.c | 2 +- arch/powerpc/platforms/book3s/vas-api.c | 2 +- arch/powerpc/platforms/cell/spufs/file.c | 14 +++++++------- arch/s390/mm/gmap.c | 3 +-- arch/x86/entry/vsyscall/vsyscall_64.c | 2 +- arch/x86/kernel/cpu/sgx/driver.c | 2 +- arch/x86/kernel/cpu/sgx/virt.c | 2 +- arch/x86/mm/pat/memtype.c | 6 +++--- arch/x86/um/mem_32.c | 2 +- drivers/acpi/pfr_telemetry.c | 2 +- drivers/android/binder.c | 3 +-- drivers/char/mspec.c | 2 +- drivers/crypto/hisilicon/qm.c | 2 +- drivers/dax/device.c | 2 +- drivers/dma/idxd/cdev.c | 2 +- drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 2 +- drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 4 ++-- drivers/gpu/drm/amd/amdkfd/kfd_doorbell.c | 4 ++-- drivers/gpu/drm/amd/amdkfd/kfd_events.c | 4 ++-- drivers/gpu/drm/amd/amdkfd/kfd_process.c | 4 ++-- drivers/gpu/drm/drm_gem.c | 2 +- drivers/gpu/drm/drm_gem_dma_helper.c | 3 +-- drivers/gpu/drm/drm_gem_shmem_helper.c | 2 +- drivers/gpu/drm/drm_vm.c | 8 ++++---- drivers/gpu/drm/etnaviv/etnaviv_gem.c | 2 +- drivers/gpu/drm/exynos/exynos_drm_gem.c | 4 ++-- drivers/gpu/drm/gma500/framebuffer.c | 2 +- drivers/gpu/drm/i810/i810_dma.c | 2 +- drivers/gpu/drm/i915/gem/i915_gem_mman.c | 4 ++-- drivers/gpu/drm/mediatek/mtk_drm_gem.c | 2 +- drivers/gpu/drm/msm/msm_gem.c | 2 +- drivers/gpu/drm/omapdrm/omap_gem.c | 3 +-- drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 3 +-- drivers/gpu/drm/tegra/gem.c | 5 ++--- drivers/gpu/drm/ttm/ttm_bo_vm.c | 3 +-- drivers/gpu/drm/virtio/virtgpu_vram.c | 2 +- drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c | 2 +- drivers/gpu/drm/xen/xen_drm_front_gem.c | 3 +-- drivers/hsi/clients/cmt_speech.c | 2 +- drivers/hwtracing/intel_th/msu.c | 2 +- drivers/hwtracing/stm/core.c | 2 +- drivers/infiniband/hw/hfi1/file_ops.c | 4 ++-- drivers/infiniband/hw/mlx5/main.c | 4 ++-- drivers/infiniband/hw/qib/qib_file_ops.c | 13 ++++++------- drivers/infiniband/hw/usnic/usnic_ib_verbs.c | 2 +- drivers/infiniband/hw/vmw_pvrdma/pvrdma_verbs.c | 2 +- .../media/common/videobuf2/videobuf2-dma-contig.c | 2 +- drivers/media/common/videobuf2/videobuf2-vmalloc.c | 2 +- drivers/media/v4l2-core/videobuf-dma-contig.c | 2 +- drivers/media/v4l2-core/videobuf-dma-sg.c | 4 ++-- drivers/media/v4l2-core/videobuf-vmalloc.c | 2 +- drivers/misc/cxl/context.c | 2 +- drivers/misc/habanalabs/common/memory.c | 2 +- drivers/misc/habanalabs/gaudi/gaudi.c | 4 ++-- drivers/misc/habanalabs/gaudi2/gaudi2.c | 8 ++++---- drivers/misc/habanalabs/goya/goya.c | 4 ++-- drivers/misc/ocxl/context.c | 4 ++-- drivers/misc/ocxl/sysfs.c | 2 +- drivers/misc/open-dice.c | 4 ++-- drivers/misc/sgi-gru/grufile.c | 4 ++-- drivers/misc/uacce/uacce.c | 2 +- drivers/sbus/char/oradax.c | 2 +- drivers/scsi/cxlflash/ocxl_hw.c | 2 +- drivers/scsi/sg.c | 2 +- drivers/staging/media/atomisp/pci/hmm/hmm_bo.c | 2 +- drivers/staging/media/deprecated/meye/meye.c | 4 ++-- .../media/deprecated/stkwebcam/stk-webcam.c | 2 +- drivers/target/target_core_user.c | 2 +- drivers/uio/uio.c | 2 +- drivers/usb/core/devio.c | 3 +-- drivers/usb/mon/mon_bin.c | 3 +-- drivers/vdpa/vdpa_user/iova_domain.c | 2 +- drivers/vfio/pci/vfio_pci_core.c | 2 +- drivers/vhost/vdpa.c | 2 +- drivers/video/fbdev/68328fb.c | 2 +- drivers/video/fbdev/core/fb_defio.c | 4 ++-- drivers/xen/gntalloc.c | 2 +- drivers/xen/gntdev.c | 4 ++-- drivers/xen/privcmd-buf.c | 2 +- drivers/xen/privcmd.c | 4 ++-- fs/aio.c | 2 +- fs/cramfs/inode.c | 2 +- fs/erofs/data.c | 2 +- fs/exec.c | 4 ++-- fs/ext4/file.c | 2 +- fs/fuse/dax.c | 2 +- fs/hugetlbfs/inode.c | 4 ++-- fs/orangefs/file.c | 3 +-- fs/proc/task_mmu.c | 2 +- fs/proc/vmcore.c | 3 +-- fs/userfaultfd.c | 2 +- fs/xfs/xfs_file.c | 2 +- include/linux/mm.h | 2 +- kernel/bpf/ringbuf.c | 4 ++-- kernel/bpf/syscall.c | 4 ++-- kernel/events/core.c | 2 +- kernel/kcov.c | 2 +- kernel/relay.c | 2 +- mm/madvise.c | 2 +- mm/memory.c | 6 +++--- mm/mlock.c | 6 +++--- mm/mmap.c | 10 +++++----- mm/mprotect.c | 2 +- mm/mremap.c | 6 +++--- mm/nommu.c | 11 ++++++----- mm/secretmem.c | 2 +- mm/shmem.c | 2 +- mm/vmalloc.c | 2 +- net/ipv4/tcp.c | 4 ++-- security/selinux/selinuxfs.c | 6 +++--- sound/core/oss/pcm_oss.c | 2 +- sound/core/pcm_native.c | 9 +++++---- sound/soc/pxa/mmp-sspa.c | 2 +- sound/usb/usx2y/us122l.c | 4 ++-- sound/usb/usx2y/usX2Yhwdep.c | 2 +- sound/usb/usx2y/usx2yhwdeppcm.c | 2 +- 120 files changed, 188 insertions(+), 199 deletions(-)Hello Suren,
Hi Hyeonggon,
[...] Whoa, it's so long. Mostly looks fine but two things I'm not sure about:quoted
diff --git a/drivers/misc/open-dice.c b/drivers/misc/open-dice.c index 9dda47b3fd70..7be4e6c9f120 100644 --- a/drivers/misc/open-dice.c +++ b/drivers/misc/open-dice.c@@ -95,12 +95,12 @@ static int open_dice_mmap(struct file *filp, struct vm_area_struct *vma) if (vma->vm_flags & VM_WRITE) return -EPERM; /* Ensure userspace cannot acquire VM_WRITE later. */ - vma->vm_flags &= ~VM_MAYWRITE; + vm_flags_clear(vma, VM_MAYSHARE); }I think it should be: s/VM_MAYSHARE/VM_MAYWRITE/
Good eye! Yes, this is definitely a bug. Will post a next version with this fix.
quoted
diff --git a/mm/mlock.c b/mm/mlock.c index 5c4fff93cd6b..ed49459e343e 100644 --- a/mm/mlock.c +++ b/mm/mlock.c@@ -380,7 +380,7 @@ static void mlock_vma_pages_range(struct vm_area_struct *vma, */ if (newflags & VM_LOCKED) newflags |= VM_IO; - WRITE_ONCE(vma->vm_flags, newflags); + vm_flags_reset(vma, newflags); lru_add_drain(); walk_page_range(vma->vm_mm, start, end, &mlock_walk_ops, NULL);@@ -388,7 +388,7 @@ static void mlock_vma_pages_range(struct vm_area_struct *vma, if (newflags & VM_IO) { newflags &= ~VM_IO; - WRITE_ONCE(vma->vm_flags, newflags); + vm_flags_reset(vma, newflags); } }wondering the if the comment above is still true? /* * There is a slight chance that concurrent page migration, * or page reclaim finding a page of this now-VM_LOCKED vma, * will call mlock_vma_folio() and raise page's mlock_count: * double counting, leaving the page unevictable indefinitely. * Communicate this danger to mlock_vma_folio() with VM_IO, * which is a VM_SPECIAL flag not allowed on VM_LOCKED vmas. * mmap_lock is held in write mode here, so this weird * combination should not be visible to other mmap_lock users; * but WRITE_ONCE so rmap walkers must see VM_IO if VM_LOCKED. */ does ACCESS_PRIVATE() still guarentee that compiler cannot mysteriously optimize writes like WRITE_ONCE()?
I don't see ACCESS_PRIVATE() providing the same guarantees as WRITE_ONCE(), therefore I think this also needs to be changed. I'll need to introduce something like vm_flags_reset_once() and use it here. vm_flags_reset_once() would do WRITE_ONCE() and otherwise would be identical to vm_flags_reset(). I'll post a new version with the fixes later today. Thanks for the review! Suren.
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