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    Subject[PATCH 4.4 76/88] mm: replace get_user_pages_unlocked() write/force parameters with gup_flags
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Lorenzo Stoakes <lstoakes@gmail.com>

    commit c164154f66f0c9b02673f07aa4f044f1d9c70274 upstream.

    This removes the 'write' and 'force' use from get_user_pages_unlocked()
    and replaces them with 'gup_flags' to make the use of FOLL_FORCE
    explicit in callers as use of this flag can result in surprising
    behaviour (and hence bugs) within the mm subsystem.

    Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
    Reviewed-by: Jan Kara <jack@suse.cz>
    Acked-by: Michal Hocko <mhocko@suse.com>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    [bwh: Backported to 4.4:
    - Also update calls from process_vm_rw_single_vec() and async_pf_execute()
    - Adjust context]
    Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/mips/mm/gup.c | 2 +-
    arch/s390/mm/gup.c | 2 +-
    arch/sh/mm/gup.c | 3 ++-
    arch/sparc/mm/gup.c | 3 ++-
    arch/x86/mm/gup.c | 2 +-
    drivers/media/pci/ivtv/ivtv-udma.c | 3 ++-
    drivers/media/pci/ivtv/ivtv-yuv.c | 8 ++++----
    drivers/scsi/st.c | 5 ++---
    drivers/video/fbdev/pvr2fb.c | 2 +-
    include/linux/mm.h | 2 +-
    mm/gup.c | 14 ++++----------
    mm/nommu.c | 11 ++---------
    mm/process_vm_access.c | 6 +++++-
    mm/util.c | 2 +-
    net/ceph/pagevec.c | 2 +-
    virt/kvm/async_pf.c | 2 +-
    16 files changed, 31 insertions(+), 38 deletions(-)

    --- a/arch/mips/mm/gup.c
    +++ b/arch/mips/mm/gup.c
    @@ -303,7 +303,7 @@ slow_irqon:

    ret = get_user_pages_unlocked(current, mm, start,
    (end - start) >> PAGE_SHIFT,
    - write, 0, pages);
    + pages, write ? FOLL_WRITE : 0);

    /* Have to be a bit careful with return values */
    if (nr > 0) {
    --- a/arch/s390/mm/gup.c
    +++ b/arch/s390/mm/gup.c
    @@ -242,7 +242,7 @@ int get_user_pages_fast(unsigned long st
    start += nr << PAGE_SHIFT;
    pages += nr;
    ret = get_user_pages_unlocked(current, mm, start,
    - nr_pages - nr, write, 0, pages);
    + nr_pages - nr, pages, write ? FOLL_WRITE : 0);
    /* Have to be a bit careful with return values */
    if (nr > 0)
    ret = (ret < 0) ? nr : ret + nr;
    --- a/arch/sh/mm/gup.c
    +++ b/arch/sh/mm/gup.c
    @@ -258,7 +258,8 @@ slow_irqon:
    pages += nr;

    ret = get_user_pages_unlocked(current, mm, start,
    - (end - start) >> PAGE_SHIFT, write, 0, pages);
    + (end - start) >> PAGE_SHIFT, pages,
    + write ? FOLL_WRITE : 0);

    /* Have to be a bit careful with return values */
    if (nr > 0) {
    --- a/arch/sparc/mm/gup.c
    +++ b/arch/sparc/mm/gup.c
    @@ -250,7 +250,8 @@ slow:
    pages += nr;

    ret = get_user_pages_unlocked(current, mm, start,
    - (end - start) >> PAGE_SHIFT, write, 0, pages);
    + (end - start) >> PAGE_SHIFT, pages,
    + write ? FOLL_WRITE : 0);

    /* Have to be a bit careful with return values */
    if (nr > 0) {
    --- a/arch/x86/mm/gup.c
    +++ b/arch/x86/mm/gup.c
    @@ -388,7 +388,7 @@ slow_irqon:

    ret = get_user_pages_unlocked(current, mm, start,
    (end - start) >> PAGE_SHIFT,
    - write, 0, pages);
    + pages, write ? FOLL_WRITE : 0);

    /* Have to be a bit careful with return values */
    if (nr > 0) {
    --- a/drivers/media/pci/ivtv/ivtv-udma.c
    +++ b/drivers/media/pci/ivtv/ivtv-udma.c
    @@ -125,7 +125,8 @@ int ivtv_udma_setup(struct ivtv *itv, un

    /* Get user pages for DMA Xfer */
    err = get_user_pages_unlocked(current, current->mm,
    - user_dma.uaddr, user_dma.page_count, 0, 1, dma->map);
    + user_dma.uaddr, user_dma.page_count, dma->map,
    + FOLL_FORCE);

    if (user_dma.page_count != err) {
    IVTV_DEBUG_WARN("failed to map user pages, returned %d instead of %d\n",
    --- a/drivers/media/pci/ivtv/ivtv-yuv.c
    +++ b/drivers/media/pci/ivtv/ivtv-yuv.c
    @@ -76,13 +76,13 @@ static int ivtv_yuv_prep_user_dma(struct

    /* Get user pages for DMA Xfer */
    y_pages = get_user_pages_unlocked(current, current->mm,
    - y_dma.uaddr, y_dma.page_count, 0, 1,
    - &dma->map[0]);
    + y_dma.uaddr, y_dma.page_count,
    + &dma->map[0], FOLL_FORCE);
    uv_pages = 0; /* silence gcc. value is set and consumed only if: */
    if (y_pages == y_dma.page_count) {
    uv_pages = get_user_pages_unlocked(current, current->mm,
    - uv_dma.uaddr, uv_dma.page_count, 0, 1,
    - &dma->map[y_pages]);
    + uv_dma.uaddr, uv_dma.page_count,
    + &dma->map[y_pages], FOLL_FORCE);
    }

    if (y_pages != y_dma.page_count || uv_pages != uv_dma.page_count) {
    --- a/drivers/scsi/st.c
    +++ b/drivers/scsi/st.c
    @@ -4821,9 +4821,8 @@ static int sgl_map_user_pages(struct st_
    current->mm,
    uaddr,
    nr_pages,
    - rw == READ,
    - 0, /* don't force */
    - pages);
    + pages,
    + rw == READ ? FOLL_WRITE : 0); /* don't force */

    /* Errors and no page mapped should return here */
    if (res < nr_pages)
    --- a/drivers/video/fbdev/pvr2fb.c
    +++ b/drivers/video/fbdev/pvr2fb.c
    @@ -687,7 +687,7 @@ static ssize_t pvr2fb_write(struct fb_in
    return -ENOMEM;

    ret = get_user_pages_unlocked(current, current->mm, (unsigned long)buf,
    - nr_pages, WRITE, 0, pages);
    + nr_pages, pages, FOLL_WRITE);

    if (ret < nr_pages) {
    nr_pages = ret;
    --- a/include/linux/mm.h
    +++ b/include/linux/mm.h
    @@ -1210,7 +1210,7 @@ long __get_user_pages_unlocked(struct ta
    struct page **pages, unsigned int gup_flags);
    long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
    unsigned long start, unsigned long nr_pages,
    - int write, int force, struct page **pages);
    + struct page **pages, unsigned int gup_flags);
    int get_user_pages_fast(unsigned long start, int nr_pages, int write,
    struct page **pages);

    --- a/mm/gup.c
    +++ b/mm/gup.c
    @@ -797,17 +797,10 @@ EXPORT_SYMBOL(__get_user_pages_unlocked)
    */
    long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
    unsigned long start, unsigned long nr_pages,
    - int write, int force, struct page **pages)
    + struct page **pages, unsigned int gup_flags)
    {
    - unsigned int flags = FOLL_TOUCH;
    -
    - if (write)
    - flags |= FOLL_WRITE;
    - if (force)
    - flags |= FOLL_FORCE;
    -
    return __get_user_pages_unlocked(tsk, mm, start, nr_pages,
    - pages, flags);
    + pages, gup_flags | FOLL_TOUCH);
    }
    EXPORT_SYMBOL(get_user_pages_unlocked);

    @@ -1427,7 +1420,8 @@ int get_user_pages_fast(unsigned long st
    pages += nr;

    ret = get_user_pages_unlocked(current, mm, start,
    - nr_pages - nr, write, 0, pages);
    + nr_pages - nr, pages,
    + write ? FOLL_WRITE : 0);

    /* Have to be a bit careful with return values */
    if (nr > 0) {
    --- a/mm/nommu.c
    +++ b/mm/nommu.c
    @@ -224,17 +224,10 @@ EXPORT_SYMBOL(__get_user_pages_unlocked)

    long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
    unsigned long start, unsigned long nr_pages,
    - int write, int force, struct page **pages)
    + struct page **pages, unsigned int gup_flags)
    {
    - unsigned int flags = 0;
    -
    - if (write)
    - flags |= FOLL_WRITE;
    - if (force)
    - flags |= FOLL_FORCE;
    -
    return __get_user_pages_unlocked(tsk, mm, start, nr_pages,
    - pages, flags);
    + pages, gup_flags);
    }
    EXPORT_SYMBOL(get_user_pages_unlocked);

    --- a/mm/process_vm_access.c
    +++ b/mm/process_vm_access.c
    @@ -88,19 +88,23 @@ static int process_vm_rw_single_vec(unsi
    ssize_t rc = 0;
    unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
    / sizeof(struct pages *);
    + unsigned int flags = 0;

    /* Work out address and page range required */
    if (len == 0)
    return 0;
    nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;

    + if (vm_write)
    + flags |= FOLL_WRITE;
    +
    while (!rc && nr_pages && iov_iter_count(iter)) {
    int pages = min(nr_pages, max_pages_per_loop);
    size_t bytes;

    /* Get the pages we're interested in */
    pages = get_user_pages_unlocked(task, mm, pa, pages,
    - vm_write, 0, process_pages);
    + process_pages, flags);
    if (pages <= 0)
    return -EFAULT;

    --- a/mm/util.c
    +++ b/mm/util.c
    @@ -278,7 +278,7 @@ int __weak get_user_pages_fast(unsigned
    {
    struct mm_struct *mm = current->mm;
    return get_user_pages_unlocked(current, mm, start, nr_pages,
    - write, 0, pages);
    + pages, write ? FOLL_WRITE : 0);
    }
    EXPORT_SYMBOL_GPL(get_user_pages_fast);

    --- a/net/ceph/pagevec.c
    +++ b/net/ceph/pagevec.c
    @@ -26,7 +26,7 @@ struct page **ceph_get_direct_page_vecto
    while (got < num_pages) {
    rc = get_user_pages_unlocked(current, current->mm,
    (unsigned long)data + ((unsigned long)got * PAGE_SIZE),
    - num_pages - got, write_page, 0, pages + got);
    + num_pages - got, pages + got, write_page ? FOLL_WRITE : 0);
    if (rc < 0)
    break;
    BUG_ON(rc == 0);
    --- a/virt/kvm/async_pf.c
    +++ b/virt/kvm/async_pf.c
    @@ -80,7 +80,7 @@ static void async_pf_execute(struct work

    might_sleep();

    - get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL);
    + get_user_pages_unlocked(NULL, mm, addr, 1, NULL, FOLL_WRITE);
    kvm_async_page_present_sync(vcpu, apf);

    spin_lock(&vcpu->async_pf.lock);

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