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mm: introduce vma_set_file function v5

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Add the new vma_set_file() function to allow changing
vma->vm_file with the necessary refcount dance.

v2: add more users of this.
v3: add missing EXPORT_SYMBOL, rebase on mmap cleanup,
    add comments why we drop the reference on two occasions.
v4: make it clear that changing an anonymous vma is illegal.
v5: move vma_set_file to mm/util.c

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v2)
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://patchwork.freedesktop.org/patch/399360/
Signed-off-by: Juhyung Park <qkrwngud825@gmail.com>
Change-Id: If77ffac122fac2da1ec34b886784381c4648b2c5
This commit is contained in:
Christian König 2020-09-14 15:09:33 +02:00 committed by spakkkk
parent 47698e5b19
commit deab481fa8
5 changed files with 20 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/dma-buf/dma-buf.c
View File

@ -1213,8 +1213,7 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
return -EINVAL;
/* readjust the vma */
fput(vma->vm_file);
vma->vm_file = get_file(dmabuf->file);
vma_set_file(vma, dmabuf->file);
vma->vm_pgoff = pgoff;
return dmabuf->ops->mmap(dmabuf, vma);

4
drivers/gpu/drm/msm/msm_gem.c
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@ -232,10 +232,8 @@ int msm_gem_mmap_obj(struct drm_gem_object *obj,
* address_space (so unmap_mapping_range does what we want,
* in particular in the case of mmap'd dmabufs)
*/
fput(vma->vm_file);
get_file(obj->filp);
vma->vm_pgoff = 0;
vma->vm_file = obj->filp;
vma_set_file(vma, obj->filp);
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
}

6
drivers/staging/android/ashmem.c
View File

@ -449,9 +449,9 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
vma_set_anonymous(vma);
}
if (vma->vm_file)
fput(vma->vm_file);
vma->vm_file = asma->file;
vma_set_file(vma, asma->file);
/* XXX: merge this with the get_file() above if possible */
fput(asma->file);
out:
mutex_unlock(&ashmem_mutex);

2
include/linux/mm.h
View File

@ -2573,6 +2573,8 @@ static inline void vma_set_page_prot(struct vm_area_struct *vma)
}
#endif
void vma_set_file(struct vm_area_struct *vma, struct file *file);
#ifdef CONFIG_NUMA_BALANCING
unsigned long change_prot_numa(struct vm_area_struct *vma,
unsigned long start, unsigned long end);

13
mm/util.c
View File

@ -4,6 +4,7 @@
#include <linux/compiler.h>
#include <linux/export.h>
#include <linux/err.h>
#include <linux/file.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/sched/task_stack.h>
@ -329,6 +330,18 @@ unsigned long randomize_page(unsigned long start, unsigned long range)
return start + (get_random_long() % range << PAGE_SHIFT);
}
/*
* Change backing file, only valid to use during initial VMA setup.
*/
void vma_set_file(struct vm_area_struct *vma, struct file *file)
{
/* Changing an anonymous vma with this is illegal */
get_file(file);
swap(vma->vm_file, file);
fput(file);
}
EXPORT_SYMBOL(vma_set_file);
#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
{