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Mon, 09 Jan 2023 12:54:22 -0800 (PST) Date: Mon, 9 Jan 2023 12:53:11 -0800 In-Reply-To: <20230109205336.3665937-1-surenb@google.com> Mime-Version: 1.0 References: <20230109205336.3665937-1-surenb@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230109205336.3665937-17-surenb@google.com> Subject: [PATCH 16/41] mm: replace vma->vm_flags indirect modification in ksm_madvise From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, hughlynch@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230109_205435_705585_3C0F9B5A X-CRM114-Status: GOOD ( 12.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 --- 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 3811d6c86d09..e47387f8be6d 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 5cb401aa2b9d..5376246a3052 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -352,6 +352,8 @@ 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 dd02780c387f..d05c41b289db 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2471,6 +2471,8 @@ 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: /*