[PATCH v2 4/6] mm: replace vma->vm_flags indirect modification in ksm_madvise
From: Suren Baghdasaryan <surenb@google.com>
Date: 2023-01-25 08:43:28
Also in:
alsa-devel, amd-gfx, bpf, dmaengine, dri-devel, intel-gfx, kexec, kvm, linux-acpi, linux-arch, linux-arm-msm, linux-crypto, linux-ext4, linux-fsdevel, linux-media, linux-mediatek, linux-mm, linux-perf-users, linux-rdma, linux-s390, linux-samsung-soc, linux-scsi, linux-staging, linux-tegra, linux-um, linux-usb, linux-xfs, linuxppc-dev, lkml, loongarch, netdev, nvdimm, selinux, sparclinux, target-devel, xen-devel
Subsystem:
kernel virtual machine for powerpc (kvm/powerpc), linux for powerpc (32-bit and 64-bit), memory management, memory management - ksm (kernel samepage merging), memory management - thp (transparent huge page), s390 architecture, the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Andrew Morton, David Hildenbrand, Lorenzo Stoakes, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds
Replace indirect modifications to vma->vm_flags with calls to modifier functions to be able to track flag changes and to keep vma locking correctness. Add a BUG_ON check in ksm_madvise() to catch indirect vm_flags modification attempts. Signed-off-by: Suren Baghdasaryan <surenb@google.com> --- arch/powerpc/kvm/book3s_hv_uvmem.c | 5 ++++- arch/s390/mm/gmap.c | 5 ++++- mm/khugepaged.c | 2 ++ mm/ksm.c | 2 ++ 4 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 1d67baa5557a..325a7a47d348 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c@@ -393,6 +393,7 @@ static int kvmppc_memslot_page_merge(struct kvm *kvm, { unsigned long gfn = memslot->base_gfn; unsigned long end, start = gfn_to_hva(kvm, gfn); + unsigned long vm_flags; int ret = 0; struct vm_area_struct *vma; int merge_flag = (merge) ? MADV_MERGEABLE : MADV_UNMERGEABLE;
@@ -409,12 +410,14 @@ static int kvmppc_memslot_page_merge(struct kvm *kvm, ret = H_STATE; break; } + vm_flags = vma->vm_flags; ret = ksm_madvise(vma, vma->vm_start, vma->vm_end, - merge_flag, &vma->vm_flags); + merge_flag, &vm_flags); if (ret) { ret = H_STATE; break; } + reset_vm_flags(vma, vm_flags); start = vma->vm_end; } while (end > vma->vm_end);
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 3a695b8a1e3c..d5eb47dcdacb 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c@@ -2587,14 +2587,17 @@ int gmap_mark_unmergeable(void) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; + unsigned long vm_flags; int ret; VMA_ITERATOR(vmi, mm, 0); for_each_vma(vmi, vma) { + vm_flags = vma->vm_flags; ret = ksm_madvise(vma, vma->vm_start, vma->vm_end, - MADV_UNMERGEABLE, &vma->vm_flags); + MADV_UNMERGEABLE, &vm_flags); if (ret) return ret; + reset_vm_flags(vma, vm_flags); } mm->def_flags &= ~VM_MERGEABLE; return 0;
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 8abc59345bf2..76b24cd0c179 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c@@ -354,6 +354,8 @@ struct attribute_group khugepaged_attr_group = { int hugepage_madvise(struct vm_area_struct *vma, unsigned long *vm_flags, int advice) { + /* vma->vm_flags can be changed only using modifier functions */ + BUG_ON(vm_flags == &vma->vm_flags); switch (advice) { case MADV_HUGEPAGE: #ifdef CONFIG_S390
diff --git a/mm/ksm.c b/mm/ksm.c
index 04f1c8c2df11..992b2be9f5e6 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c@@ -2573,6 +2573,8 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start, struct mm_struct *mm = vma->vm_mm; int err; + /* vma->vm_flags can be changed only using modifier functions */ + BUG_ON(vm_flags == &vma->vm_flags); switch (advice) { case MADV_MERGEABLE: /*
--
2.39.1