From 6a1960b8a8773324d870fa32ba68ff3106523a95 Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Tue, 3 Oct 2023 00:14:54 +0100 Subject: [PATCH] mm/gup: adapt get_user_page_vma_remote() to never return NULL get_user_pages_remote() will never return 0 except in the case of FOLL_NOWAIT being specified, which we explicitly disallow. This simplifies error handling for the caller and avoids the awkwardness of dealing with both errors and failing to pin. Failing to pin here is an error. Link: https://lkml.kernel.org/r/00319ce292d27b3aae76a0eb220ce3f528187508.1696288092.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes Suggested-by: Arnd Bergmann Reviewed-by: Arnd Bergmann Acked-by: Catalin Marinas Reviewed-by: David Hildenbrand Reviewed-by: Jason Gunthorpe Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: John Hubbard Cc: Mark Rutland Cc: Namhyung Kim Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Richard Cochran Cc: Will Deacon Signed-off-by: Andrew Morton --- arch/arm64/kernel/mte.c | 4 ++-- include/linux/mm.h | 12 +++++++++--- kernel/events/uprobes.c | 4 ++-- mm/memory.c | 3 +-- 4 files changed, 14 insertions(+), 9 deletions(-) diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 4edecaac8f91..8878b392df58 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -411,8 +411,8 @@ static int __access_remote_tags(struct mm_struct *mm, unsigned long addr, struct page *page = get_user_page_vma_remote(mm, addr, gup_flags, &vma); - if (IS_ERR_OR_NULL(page)) { - err = page == NULL ? -EIO : PTR_ERR(page); + if (IS_ERR(page)) { + err = PTR_ERR(page); break; } diff --git a/include/linux/mm.h b/include/linux/mm.h index 7b89f7bd420d..fa608cba041f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2425,6 +2425,9 @@ long pin_user_pages_remote(struct mm_struct *mm, unsigned int gup_flags, struct page **pages, int *locked); +/* + * Retrieves a single page alongside its VMA. Does not support FOLL_NOWAIT. + */ static inline struct page *get_user_page_vma_remote(struct mm_struct *mm, unsigned long addr, int gup_flags, @@ -2432,12 +2435,15 @@ static inline struct page *get_user_page_vma_remote(struct mm_struct *mm, { struct page *page; struct vm_area_struct *vma; - int got = get_user_pages_remote(mm, addr, 1, gup_flags, &page, NULL); + int got; + + if (WARN_ON_ONCE(unlikely(gup_flags & FOLL_NOWAIT))) + return ERR_PTR(-EINVAL); + + got = get_user_pages_remote(mm, addr, 1, gup_flags, &page, NULL); if (got < 0) return ERR_PTR(got); - if (got == 0) - return NULL; vma = vma_lookup(mm, addr); if (WARN_ON_ONCE(!vma)) { diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 3048589e2e85..435aac1d8c27 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -474,8 +474,8 @@ retry: gup_flags |= FOLL_SPLIT_PMD; /* Read the page with vaddr into memory */ old_page = get_user_page_vma_remote(mm, vaddr, gup_flags, &vma); - if (IS_ERR_OR_NULL(old_page)) - return old_page ? PTR_ERR(old_page) : 0; + if (IS_ERR(old_page)) + return PTR_ERR(old_page); ret = verify_opcode(old_page, vaddr, &opcode); if (ret <= 0) diff --git a/mm/memory.c b/mm/memory.c index e47c36c0aef0..1f88e4f6fbf2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5815,7 +5815,7 @@ static int __access_remote_vm(struct mm_struct *mm, unsigned long addr, struct page *page = get_user_page_vma_remote(mm, addr, gup_flags, &vma); - if (IS_ERR_OR_NULL(page)) { + if (IS_ERR(page)) { /* We might need to expand the stack to access it */ vma = vma_lookup(mm, addr); if (!vma) { @@ -5829,7 +5829,6 @@ static int __access_remote_vm(struct mm_struct *mm, unsigned long addr, continue; } - /* * Check if this is a VM_IO | VM_PFNMAP VMA, which * we can access using slightly different code.