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t=1674725274; bh=SoMuUCKccvLBFFlS2yaoZNAJ6vi8hf11UD5LIFXhHPI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=j//Fl5kIolRbc8e9oVCQ2yHwbpz0TuieYLSj+mDFLpa1qwKxXUhf5PJmcO75Ujh3s twG4fOSIQIUcY+3MnnJB2LFgFpgYd/SthHle/+axd8X6B40DgEguPrzEIDstErfxF8 ko0Mb6Gc7DtRkgMx2KamDNuuhnb/IfTXyWRUAI8okoWPpJCrU+5VBwHmsXg3EJf5FZ gJ2/jlRLLWN+Ab/FNlmJJeHDKv+eOxzvt50mhgYbacQHyS9BYwkvyF434NJwFVAGsI dA9tzS1LLkbpY2wsykh131+0o90nnu9297soO8LSNeHRZppCk70KOOayN+gSrVyob+ 3jVum/MlvC8IQ== Date: Thu, 26 Jan 2023 11:26:58 +0200 From: Mike Rapoport To: Suren Baghdasaryan Subject: Re: [PATCH v2 4/6] mm: replace vma->vm_flags indirect modification in ksm_madvise Message-ID: References: <20230125083851.27759-1-surenb@google.com> <20230125083851.27759-5-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230125083851.27759-5-surenb@google.com> X-Mailman-Approved-At: Thu, 26 Jan 2023 20:59:36 +1100 X-BeenThere: linuxppc-dev@lists.ozlabs.org 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mgorman@techsingularity.net, linux-accelerators@lists.ozlabs.org, l.stach@pengutronix.de Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Jan 25, 2023 at 12:38:49AM -0800, Suren Baghdasaryan wrote: > 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 Acked-by: Mike Rapoport (IBM) > --- > 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 > >