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Sat, 15 Apr 2023 02:08:41 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Cc: Matthew Wilcox , David Hildenbrand , Lorenzo Stoakes Subject: [PATCH v2 4/7] mm/gup: introduce the FOLL_SAME_FILE GUP flag Date: Sat, 15 Apr 2023 10:08:39 +0100 Message-Id: <45702c7b87c8487455783b482b67dfcf2d24e6a9.1681547405.git.lstoakes@gmail.com> X-Mailer: git-send-email 2.40.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: 3h1qq7t7es8pewxce4bh81fwjfn1615r X-Rspamd-Queue-Id: 195C218000E X-HE-Tag: 1681549723-891445 X-HE-Meta: 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 3LPbocD8 a9JK9hNUtCXhYfu6ttzFtGuUGDhhlVUNqN2XtpTtIvkcF5b9vUsmu3AThfWrHwBpDQ8xfC+5f6HBzJWBDAjne5d9sgtPmNoD2frdwVUBeXLHPuYp3Bo+sYWMNrIHS4X/RDp05pA5E47VDeIzcQyO1VeDSqm/7cq2PI4fY5ZNAIRT+dd8dlhuXnfpB+OA5OELDEmWNH9oov7suQQBKJU6wjyzg5aUyCtDSuuvFoFhdnoBFclVEOHLphtaoDkBmlKl8bm9G4UWNRiE9sPt+4OYyVIU/ZoUoojff0aRJSNnZY0uOrl1y2JFUywMB1wZuQ/q6Jp3Wdjw6yBlzdztt3BtugBeVgLP5znKnbceWTRkz2LD0ptQRHMbZMQTnrdE/1zgJPqED1enlYo7OVFDQ2fE+DEjkNGyaq+/IvXKT38flhyMeM938VaX0BmbHaeWPClZNQBtJi2ikvmd3XTTZC4R+SiPObwlAeyBmDAjj5v1/76DsevI= 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: This flag causes GUP to assert that all VMAs within the input range possess the same vma->vm_file. If not, the operation fails. This is part of a patch series which eliminates the vmas parameter from the GUP API, implementing the one remaining assertion within the entire kernel that requires access to the VMAs associated with a GUP range. Signed-off-by: Lorenzo Stoakes --- include/linux/mm_types.h | 2 ++ mm/gup.c | 16 ++++++++++++---- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3fc9e680f174..84d1aec9dbab 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1185,6 +1185,8 @@ enum { FOLL_PCI_P2PDMA = 1 << 10, /* allow interrupts from generic signals */ FOLL_INTERRUPTIBLE = 1 << 11, + /* assert that the range spans VMAs with the same vma->vm_file */ + FOLL_SAME_FILE = 1 << 12, /* See also internal only FOLL flags in mm/internal.h */ }; diff --git a/mm/gup.c b/mm/gup.c index 9440aa54c741..3954ce499a4a 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -959,7 +959,8 @@ static int faultin_page(struct vm_area_struct *vma, return 0; } -static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) +static int check_vma_flags(struct vm_area_struct *vma, struct file *file, + unsigned long gup_flags) { vm_flags_t vm_flags = vma->vm_flags; int write = (gup_flags & FOLL_WRITE); @@ -968,7 +969,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) if (vm_flags & (VM_IO | VM_PFNMAP)) return -EFAULT; - if (gup_flags & FOLL_ANON && !vma_is_anonymous(vma)) + if ((gup_flags & FOLL_ANON) && !vma_is_anonymous(vma)) return -EFAULT; if ((gup_flags & FOLL_LONGTERM) && vma_is_fsdax(vma)) @@ -977,6 +978,9 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) if (vma_is_secretmem(vma)) return -EFAULT; + if ((gup_flags & FOLL_SAME_FILE) && vma->vm_file != file) + return -EFAULT; + if (write) { if (!(vm_flags & VM_WRITE)) { if (!(gup_flags & FOLL_FORCE)) @@ -1081,6 +1085,7 @@ static long __get_user_pages(struct mm_struct *mm, long ret = 0, i = 0; struct vm_area_struct *vma = NULL; struct follow_page_context ctx = { NULL }; + struct file *file = NULL; if (!nr_pages) return 0; @@ -1111,10 +1116,13 @@ static long __get_user_pages(struct mm_struct *mm, ret = -EFAULT; goto out; } - ret = check_vma_flags(vma, gup_flags); + ret = check_vma_flags(vma, i == 0 ? vma->vm_file : file, + gup_flags); if (ret) goto out; + file = vma->vm_file; + if (is_vm_hugetlb_page(vma)) { i = follow_hugetlb_page(mm, vma, pages, vmas, &start, &nr_pages, i, @@ -1595,7 +1603,7 @@ long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start, * We want to report -EINVAL instead of -EFAULT for any permission * problems or incompatible mappings. */ - if (check_vma_flags(vma, gup_flags)) + if (check_vma_flags(vma, vma->vm_file, gup_flags)) return -EINVAL; ret = __get_user_pages(mm, start, nr_pages, gup_flags, -- 2.40.0