Commit 6a1960b8 authored by Lorenzo Stoakes's avatar Lorenzo Stoakes Committed by Andrew Morton
Browse files

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: default avatarLorenzo Stoakes <lstoakes@gmail.com>
Suggested-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 9c4b2142

arch/arm64/kernel/mte.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

		}

include/linux/mm.h

+9 −3
Original line number Diff line number Diff line
@@ -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)) {

kernel/events/uprobes.c

+2 −2
Original line number Diff line number Diff line
@@ -474,8 +474,8 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, 
		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)

mm/memory.c

+1 −2
Original line number Diff line number Diff line
@@ -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.