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[184.145.4.219]) by smtp.gmail.com with ESMTPSA id q7sm2094142qki.17.2021.05.27.13.23.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 May 2021 13:23:47 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Mike Rapoport , peterx@redhat.com, Andrew Morton , Mike Kravetz , Jerome Glisse , Miaohe Lin , Nadav Amit , Hugh Dickins , Matthew Wilcox , Jason Gunthorpe , "Kirill A . Shutemov" , Andrea Arcangeli , Axel Rasmussen Subject: [PATCH v3 26/27] mm/userfaultfd: Enable write protection for shmem & hugetlbfs Date: Thu, 27 May 2021 16:23:45 -0400 Message-Id: <20210527202345.32356-1-peterx@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210527201927.29586-1-peterx@redhat.com> References: <20210527201927.29586-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We've had all the necessary changes ready for both shmem and hugetlbfs. Turn on all the shmem/hugetlbfs switches for userfaultfd-wp. We can expand UFFD_API_RANGE_IOCTLS_BASIC with _UFFDIO_WRITEPROTECT too because all existing types now support write protection mode. Since vma_can_userfault() will be used elsewhere, move into userfaultfd_k.h. Signed-off-by: Peter Xu --- fs/userfaultfd.c | 18 ------------------ include/linux/userfaultfd_k.h | 12 ++++++++++++ include/uapi/linux/userfaultfd.h | 10 ++++++++-- mm/userfaultfd.c | 9 +++------ 4 files changed, 23 insertions(+), 26 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 6ef7b56760bf..140bab07935e 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1275,24 +1275,6 @@ static __always_inline int validate_range(struct mm_struct *mm, return 0; } -static inline bool vma_can_userfault(struct vm_area_struct *vma, - unsigned long vm_flags) -{ - /* FIXME: add WP support to hugetlbfs and shmem */ - if (vm_flags & VM_UFFD_WP) { - if (is_vm_hugetlb_page(vma) || vma_is_shmem(vma)) - return false; - } - - if (vm_flags & VM_UFFD_MINOR) { - if (!(is_vm_hugetlb_page(vma) || vma_is_shmem(vma))) - return false; - } - - return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) || - vma_is_shmem(vma); -} - static int userfaultfd_register(struct userfaultfd_ctx *ctx, unsigned long arg) { diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index ca3f794d07e9..489fb375e66c 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -16,6 +16,7 @@ #include #include #include +#include /* The set of all possible UFFD-related VM flags. */ #define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR) @@ -138,6 +139,17 @@ static inline bool userfaultfd_armed(struct vm_area_struct *vma) return vma->vm_flags & __VM_UFFD_FLAGS; } +static inline bool vma_can_userfault(struct vm_area_struct *vma, + unsigned long vm_flags) +{ + if (vm_flags & VM_UFFD_MINOR) + return is_vm_hugetlb_page(vma) || vma_is_shmem(vma); + + return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) || + vma_is_shmem(vma); +} + + extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *); extern void dup_userfaultfd_complete(struct list_head *); diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h index 159a74e9564f..09b7ec69c97d 100644 --- a/include/uapi/linux/userfaultfd.h +++ b/include/uapi/linux/userfaultfd.h @@ -32,7 +32,8 @@ UFFD_FEATURE_SIGBUS | \ UFFD_FEATURE_THREAD_ID | \ UFFD_FEATURE_MINOR_HUGETLBFS | \ - UFFD_FEATURE_MINOR_SHMEM) + UFFD_FEATURE_MINOR_SHMEM | \ + UFFD_FEATURE_WP_HUGETLBFS_SHMEM) #define UFFD_API_IOCTLS \ ((__u64)1 << _UFFDIO_REGISTER | \ (__u64)1 << _UFFDIO_UNREGISTER | \ @@ -46,7 +47,8 @@ #define UFFD_API_RANGE_IOCTLS_BASIC \ ((__u64)1 << _UFFDIO_WAKE | \ (__u64)1 << _UFFDIO_COPY | \ - (__u64)1 << _UFFDIO_CONTINUE) + (__u64)1 << _UFFDIO_CONTINUE | \ + (__u64)1 << _UFFDIO_WRITEPROTECT) /* * Valid ioctl command number range with this API is from 0x00 to @@ -189,6 +191,9 @@ struct uffdio_api { * * UFFD_FEATURE_MINOR_SHMEM indicates the same support as * UFFD_FEATURE_MINOR_HUGETLBFS, but for shmem-backed pages instead. + * + * UFFD_FEATURE_WP_HUGETLBFS_SHMEM indicates that userfaultfd + * write-protection mode is supported on both shmem and hugetlbfs. */ #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0) #define UFFD_FEATURE_EVENT_FORK (1<<1) @@ -201,6 +206,7 @@ struct uffdio_api { #define UFFD_FEATURE_THREAD_ID (1<<8) #define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9) #define UFFD_FEATURE_MINOR_SHMEM (1<<10) +#define UFFD_FEATURE_WP_HUGETLBFS_SHMEM (1<<11) __u64 features; __u64 ioctls; diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index af79f3d3a001..7ff9176149e0 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -772,15 +772,12 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, err = -ENOENT; dst_vma = find_dst_vma(dst_mm, start, len); - /* - * Make sure the vma is not shared, that the dst range is - * both valid and fully within a single existing vma. - */ - if (!dst_vma || (dst_vma->vm_flags & VM_SHARED)) + + if (!dst_vma) goto out_unlock; if (!userfaultfd_wp(dst_vma)) goto out_unlock; - if (!vma_is_anonymous(dst_vma)) + if (!vma_can_userfault(dst_vma, dst_vma->vm_flags)) goto out_unlock; if (is_vm_hugetlb_page(dst_vma)) { -- 2.31.1