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Shutemov" , Hugh Dickins , Axel Rasmussen , Matthew Wilcox , Andrew Morton , Andrea Arcangeli , Nadav Amit Subject: [PATCH RFC 29/30] userfaultfd: Enable write protection for shmem & hugetlbfs Date: Fri, 15 Jan 2021 12:09:06 -0500 Message-Id: <20210115170907.24498-30-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210115170907.24498-1-peterx@redhat.com> References: <20210115170907.24498-1-peterx@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: We've had all the necessary changes ready for both shmem and hugetlbfs. Turn on all the shmem/hugetlbfs switches for userfaultfd-wp. Now we can remove the flags parameter for vma_can_userfault() since not used any more. Meanwhile, 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 | 17 ++++------------- include/linux/userfaultfd_k.h | 7 +++++++ include/uapi/linux/userfaultfd.h | 3 ++- mm/userfaultfd.c | 10 +++------- 4 files changed, 16 insertions(+), 21 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 3264ec46242b..88ad90fc8539 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1307,15 +1307,6 @@ 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 */ - return vma_is_anonymous(vma) || - ((is_vm_hugetlb_page(vma) || vma_is_shmem(vma)) && - !(vm_flags & VM_UFFD_WP)); -} - static int userfaultfd_register(struct userfaultfd_ctx *ctx, unsigned long arg) { @@ -1394,7 +1385,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, /* check not compatible vmas */ ret = -EINVAL; - if (!vma_can_userfault(cur, vm_flags)) + if (!vma_can_userfault(cur)) goto out_unlock; /* @@ -1453,7 +1444,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, do { cond_resched(); - BUG_ON(!vma_can_userfault(vma, vm_flags)); + BUG_ON(!vma_can_userfault(vma)); BUG_ON(vma->vm_userfaultfd_ctx.ctx && vma->vm_userfaultfd_ctx.ctx != ctx); WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); @@ -1602,7 +1593,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, * provides for more strict behavior to notice * unregistration errors. */ - if (!vma_can_userfault(cur, cur->vm_flags)) + if (!vma_can_userfault(cur)) goto out_unlock; found = true; @@ -1616,7 +1607,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, do { cond_resched(); - BUG_ON(!vma_can_userfault(vma, vma->vm_flags)); + BUG_ON(!vma_can_userfault(vma)); /* * Nothing to do: this vma is already registered into this diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 7d14444862d4..fd7031173949 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -16,6 +16,7 @@ #include #include #include +#include /* * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining @@ -88,6 +89,12 @@ static inline bool userfaultfd_armed(struct vm_area_struct *vma) return vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP); } +static inline bool vma_can_userfault(struct vm_area_struct *vma) +{ + return vma_is_anonymous(vma) || vma_is_shmem(vma) || + is_vm_hugetlb_page(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 e7e98bde221f..83bcd739de50 100644 --- a/include/uapi/linux/userfaultfd.h +++ b/include/uapi/linux/userfaultfd.h @@ -39,7 +39,8 @@ (__u64)1 << _UFFDIO_WRITEPROTECT) #define UFFD_API_RANGE_IOCTLS_BASIC \ ((__u64)1 << _UFFDIO_WAKE | \ - (__u64)1 << _UFFDIO_COPY) + (__u64)1 << _UFFDIO_COPY | \ + (__u64)1 << _UFFDIO_WRITEPROTECT) /* * Valid ioctl command number range with this API is from 0x00 to diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 1dff5b9a2c26..3ad52f01553b 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -445,7 +445,6 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, dst_addr); } else { - VM_WARN_ON_ONCE(wp_copy); if (!zeropage) err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, @@ -671,15 +670,12 @@ 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)) goto out_unlock; if (is_vm_hugetlb_page(dst_vma)) {