The patch titled
Subject: mm/gup: remove vmas parameter from get_user_pages_remote()
has been added to the -mm mm-unstable branch. Its filename is
mm-gup-remove-vmas-parameter-from-get_user_pages_remote.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-gup-remove-vmas-parameter-from-get_user_pages_remote.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Subject: mm/gup: remove vmas parameter from get_user_pages_remote()
Date: Wed, 17 May 2023 20:25:39 +0100
The only instances of get_user_pages_remote() invocations which used the
vmas parameter were for a single page which can instead simply look up the
VMA directly. In particular:-
- __update_ref_ctr() looked up the VMA but did nothing with it so we simply
remove it.
- __access_remote_vm() was already using vma_lookup() when the original
lookup failed so by doing the lookup directly this also de-duplicates the
code.
We are able to perform these VMA operations as we already hold the
mmap_lock in order to be able to call get_user_pages_remote().
As part of this work we add get_user_page_vma_remote() which abstracts the
VMA lookup, error handling and decrementing the page reference count should
the VMA lookup fail.
This forms part of a broader set of patches intended to eliminate the vmas
parameter altogether.
Link: https://lkml.kernel.org/r/d20128c849ecdbf4dd01cc828fcec32127ed939a.1684350871.git.lstoakes@xxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx> (for arm64)
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx> (for s390)
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/mte.c | 17 +++++++++--------
arch/s390/kvm/interrupt.c | 2 +-
fs/exec.c | 2 +-
include/linux/mm.h | 34 +++++++++++++++++++++++++++++++---
kernel/events/uprobes.c | 13 +++++--------
mm/gup.c | 12 ++++--------
mm/memory.c | 20 ++++++++++----------
mm/rmap.c | 2 +-
security/tomoyo/domain.c | 2 +-
virt/kvm/async_pf.c | 3 +--
10 files changed, 64 insertions(+), 43 deletions(-)
--- a/arch/arm64/kernel/mte.c~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/arch/arm64/kernel/mte.c
@@ -419,10 +419,9 @@ long get_mte_ctrl(struct task_struct *ta
static int __access_remote_tags(struct mm_struct *mm, unsigned long addr,
struct iovec *kiov, unsigned int gup_flags)
{
- struct vm_area_struct *vma;
void __user *buf = kiov->iov_base;
size_t len = kiov->iov_len;
- int ret;
+ int err = 0;
int write = gup_flags & FOLL_WRITE;
if (!access_ok(buf, len))
@@ -432,14 +431,16 @@ static int __access_remote_tags(struct m
return -EIO;
while (len) {
+ struct vm_area_struct *vma;
unsigned long tags, offset;
void *maddr;
- struct page *page = NULL;
+ struct page *page = get_user_page_vma_remote(mm, addr,
+ gup_flags, &vma);
- ret = get_user_pages_remote(mm, addr, 1, gup_flags, &page,
- &vma, NULL);
- if (ret <= 0)
+ if (IS_ERR_OR_NULL(page)) {
+ err = page == NULL ? -EIO : PTR_ERR(page);
break;
+ }
/*
* Only copy tags if the page has been mapped as PROT_MTE
@@ -449,7 +450,7 @@ static int __access_remote_tags(struct m
* was never mapped with PROT_MTE.
*/
if (!(vma->vm_flags & VM_MTE)) {
- ret = -EOPNOTSUPP;
+ err = -EOPNOTSUPP;
put_page(page);
break;
}
@@ -482,7 +483,7 @@ static int __access_remote_tags(struct m
kiov->iov_len = buf - kiov->iov_base;
if (!kiov->iov_len) {
/* check for error accessing the tracee's address space */
- if (ret <= 0)
+ if (err)
return -EIO;
else
return -EFAULT;
--- a/arch/s390/kvm/interrupt.c~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/arch/s390/kvm/interrupt.c
@@ -2777,7 +2777,7 @@ static struct page *get_map_page(struct
mmap_read_lock(kvm->mm);
get_user_pages_remote(kvm->mm, uaddr, 1, FOLL_WRITE,
- &page, NULL, NULL);
+ &page, NULL);
mmap_read_unlock(kvm->mm);
return page;
}
--- a/fs/exec.c~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/fs/exec.c
@@ -220,7 +220,7 @@ static struct page *get_arg_page(struct
*/
mmap_read_lock(bprm->mm);
ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
- &page, NULL, NULL);
+ &page, NULL);
mmap_read_unlock(bprm->mm);
if (ret <= 0)
return NULL;
--- a/include/linux/mm.h~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/include/linux/mm.h
@@ -2366,6 +2366,9 @@ static inline void unmap_shared_mapping_
unmap_mapping_range(mapping, holebegin, holelen, 0);
}
+static inline struct vm_area_struct *vma_lookup(struct mm_struct *mm,
+ unsigned long addr);
+
extern int access_process_vm(struct task_struct *tsk, unsigned long addr,
void *buf, int len, unsigned int gup_flags);
extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
@@ -2374,13 +2377,38 @@ extern int __access_remote_vm(struct mm_
void *buf, int len, unsigned int gup_flags);
long get_user_pages_remote(struct mm_struct *mm,
- unsigned long start, unsigned long nr_pages,
- unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas, int *locked);
+ unsigned long start, unsigned long nr_pages,
+ unsigned int gup_flags, struct page **pages,
+ int *locked);
long pin_user_pages_remote(struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
int *locked);
+
+static inline struct page *get_user_page_vma_remote(struct mm_struct *mm,
+ unsigned long addr,
+ int gup_flags,
+ struct vm_area_struct **vmap)
+{
+ struct page *page;
+ struct vm_area_struct *vma;
+ int 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)) {
+ put_page(page);
+ return ERR_PTR(-EINVAL);
+ }
+
+ *vmap = vma;
+ return page;
+}
+
long get_user_pages(unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages);
long pin_user_pages(unsigned long start, unsigned long nr_pages,
--- a/kernel/events/uprobes.c~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/kernel/events/uprobes.c
@@ -365,7 +365,6 @@ __update_ref_ctr(struct mm_struct *mm, u
{
void *kaddr;
struct page *page;
- struct vm_area_struct *vma;
int ret;
short *ptr;
@@ -373,7 +372,7 @@ __update_ref_ctr(struct mm_struct *mm, u
return -EINVAL;
ret = get_user_pages_remote(mm, vaddr, 1,
- FOLL_WRITE, &page, &vma, NULL);
+ FOLL_WRITE, &page, NULL);
if (unlikely(ret <= 0)) {
/*
* We are asking for 1 page. If get_user_pages_remote() fails,
@@ -474,10 +473,9 @@ retry:
if (is_register)
gup_flags |= FOLL_SPLIT_PMD;
/* Read the page with vaddr into memory */
- ret = get_user_pages_remote(mm, vaddr, 1, gup_flags,
- &old_page, &vma, NULL);
- if (ret <= 0)
- return ret;
+ old_page = get_user_page_vma_remote(mm, vaddr, gup_flags, &vma);
+ if (IS_ERR_OR_NULL(old_page))
+ return PTR_ERR(old_page);
ret = verify_opcode(old_page, vaddr, &opcode);
if (ret <= 0)
@@ -2027,8 +2025,7 @@ static int is_trap_at_addr(struct mm_str
* but we treat this as a 'remote' access since it is
* essentially a kernel access to the memory.
*/
- result = get_user_pages_remote(mm, vaddr, 1, FOLL_FORCE, &page,
- NULL, NULL);
+ result = get_user_pages_remote(mm, vaddr, 1, FOLL_FORCE, &page, NULL);
if (result < 0)
return result;
--- a/mm/gup.c~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/mm/gup.c
@@ -2208,8 +2208,6 @@ static bool is_valid_gup_args(struct pag
* @pages: array that receives pointers to the pages pinned.
* Should be at least nr_pages long. Or NULL, if caller
* only intends to ensure the pages are faulted in.
- * @vmas: array of pointers to vmas corresponding to each page.
- * Or NULL if the caller does not require them.
* @locked: pointer to lock flag indicating whether lock is held and
* subsequently whether VM_FAULT_RETRY functionality can be
* utilised. Lock must initially be held.
@@ -2224,8 +2222,6 @@ static bool is_valid_gup_args(struct pag
*
* The caller is responsible for releasing returned @pages, via put_page().
*
- * @vmas are valid only as long as mmap_lock is held.
- *
* Must be called with mmap_lock held for read or write.
*
* get_user_pages_remote walks a process's page tables and takes a reference
@@ -2262,15 +2258,15 @@ static bool is_valid_gup_args(struct pag
long get_user_pages_remote(struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas, int *locked)
+ int *locked)
{
int local_locked = 1;
- if (!is_valid_gup_args(pages, vmas, locked, &gup_flags,
+ if (!is_valid_gup_args(pages, NULL, locked, &gup_flags,
FOLL_TOUCH | FOLL_REMOTE))
return -EINVAL;
- return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
+ return __get_user_pages_locked(mm, start, nr_pages, pages, NULL,
locked ? locked : &local_locked,
gup_flags);
}
@@ -2280,7 +2276,7 @@ EXPORT_SYMBOL(get_user_pages_remote);
long get_user_pages_remote(struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas, int *locked)
+ int *locked)
{
return 0;
}
--- a/mm/memory.c~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/mm/memory.c
@@ -5590,7 +5590,6 @@ EXPORT_SYMBOL_GPL(generic_access_phys);
int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
int len, unsigned int gup_flags)
{
- struct vm_area_struct *vma;
void *old_buf = buf;
int write = gup_flags & FOLL_WRITE;
@@ -5599,29 +5598,30 @@ int __access_remote_vm(struct mm_struct
/* ignore errors, just check how much was successfully transferred */
while (len) {
- int bytes, ret, offset;
+ int bytes, offset;
void *maddr;
- struct page *page = NULL;
+ struct vm_area_struct *vma = NULL;
+ struct page *page = get_user_page_vma_remote(mm, addr,
+ gup_flags, &vma);
- ret = get_user_pages_remote(mm, addr, 1,
- gup_flags, &page, &vma, NULL);
- if (ret <= 0) {
+ if (IS_ERR_OR_NULL(page)) {
#ifndef CONFIG_HAVE_IOREMAP_PROT
break;
#else
+ int res = 0;
+
/*
* Check if this is a VM_IO | VM_PFNMAP VMA, which
* we can access using slightly different code.
*/
- vma = vma_lookup(mm, addr);
if (!vma)
break;
if (vma->vm_ops && vma->vm_ops->access)
- ret = vma->vm_ops->access(vma, addr, buf,
+ res = vma->vm_ops->access(vma, addr, buf,
len, write);
- if (ret <= 0)
+ if (res <= 0)
break;
- bytes = ret;
+ bytes = res;
#endif
} else {
bytes = len;
--- a/mm/rmap.c~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/mm/rmap.c
@@ -2328,7 +2328,7 @@ int make_device_exclusive_range(struct m
npages = get_user_pages_remote(mm, start, npages,
FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD,
- pages, NULL, NULL);
+ pages, NULL);
if (npages < 0)
return npages;
--- a/security/tomoyo/domain.c~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/security/tomoyo/domain.c
@@ -916,7 +916,7 @@ bool tomoyo_dump_page(struct linux_binpr
*/
mmap_read_lock(bprm->mm);
ret = get_user_pages_remote(bprm->mm, pos, 1,
- FOLL_FORCE, &page, NULL, NULL);
+ FOLL_FORCE, &page, NULL);
mmap_read_unlock(bprm->mm);
if (ret <= 0)
return false;
--- a/virt/kvm/async_pf.c~mm-gup-remove-vmas-parameter-from-get_user_pages_remote
+++ a/virt/kvm/async_pf.c
@@ -61,8 +61,7 @@ static void async_pf_execute(struct work
* access remotely.
*/
mmap_read_lock(mm);
- get_user_pages_remote(mm, addr, 1, FOLL_WRITE, NULL, NULL,
- &locked);
+ get_user_pages_remote(mm, addr, 1, FOLL_WRITE, NULL, &locked);
if (locked)
mmap_read_unlock(mm);
_
Patches currently in -mm which might be from lstoakes@xxxxxxxxx are
mm-mmap-separate-writenotify-and-dirty-tracking-logic.patch
mm-gup-disallow-foll_longterm-gup-nonfast-writing-to-file-backed-mappings.patch
mm-gup-disallow-foll_longterm-gup-fast-writing-to-file-backed-mappings.patch
mm-gup-add-missing-gup_must_unshare-check-to-gup_huge_pgd.patch
mm-gup-remove-unused-vmas-parameter-from-get_user_pages.patch
mm-gup-remove-unused-vmas-parameter-from-pin_user_pages_remote.patch
mm-gup-remove-vmas-parameter-from-get_user_pages_remote.patch
io_uring-rsrc-delegate-vma-file-backed-check-to-gup.patch
mm-gup-remove-vmas-parameter-from-pin_user_pages.patch
mm-gup-remove-vmas-array-from-internal-gup-functions.patch
