Commit 14d07113 authored by Brian Geffon's avatar Brian Geffon Committed by Linus Torvalds
Browse files

Revert "mremap: don't allow MREMAP_DONTUNMAP on special_mappings and aio" 

This reverts commit cd544fd1.

As discussed in [1] this commit was a no-op because the mapping type was
checked in vma_to_resize before move_vma is ever called.  This meant that
vm_ops->mremap() would never be called on such mappings.  Furthermore,
we've since expanded support of MREMAP_DONTUNMAP to non-anonymous
mappings, and these special mappings are still protected by the existing
check of !VM_DONTEXPAND and !VM_PFNMAP which will result in a -EINVAL.

1. https://lkml.org/lkml/2020/12/28/2340

Link: https://lkml.kernel.org/r/20210323182520.2712101-2-bgeffon@google.com


Signed-off-by: default avatarBrian Geffon <bgeffon@google.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Reviewed-by: default avatarDmitry Safonov <0x7f454c46@gmail.com>
Cc: Alejandro Colomar <alx.manpages@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: "Michael S . Tsirkin" <mst@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sonny Rao <sonnyrao@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a4609387

arch/x86/kernel/cpu/resctrl/pseudo_lock.c

+1 −1
Original line number Diff line number Diff line
@@ -1458,7 +1458,7 @@ static int pseudo_lock_dev_release(struct inode *inode, struct file *filp) 
	return 0;

}



static int pseudo_lock_dev_mremap(struct vm_area_struct *area, unsigned long flags)

static int pseudo_lock_dev_mremap(struct vm_area_struct *area)

{

	/* Not supported */

	return -EINVAL;

fs/aio.c

+1 −4
Original line number Diff line number Diff line
@@ -323,16 +323,13 @@ static void aio_free_ring(struct kioctx *ctx) 
	}

}



static int aio_ring_mremap(struct vm_area_struct *vma, unsigned long flags)

static int aio_ring_mremap(struct vm_area_struct *vma)

{

	struct file *file = vma->vm_file;

	struct mm_struct *mm = vma->vm_mm;

	struct kioctx_table *table;

	int i, res = -EINVAL;



	if (flags & MREMAP_DONTUNMAP)

		return -EINVAL;



	spin_lock(&mm->ioctx_lock);

	rcu_read_lock();

	table = rcu_dereference(mm->ioctx_table);

include/linux/mm.h

+1 −1
Original line number Diff line number Diff line
@@ -580,7 +580,7 @@ struct vm_operations_struct { 
	void (*close)(struct vm_area_struct * area);

	/* Called any time before splitting to check if it's allowed */

	int (*may_split)(struct vm_area_struct *area, unsigned long addr);

	int (*mremap)(struct vm_area_struct *area, unsigned long flags);

	int (*mremap)(struct vm_area_struct *area);

	/*

	 * Called by mprotect() to make driver-specific permission

	 * checks before mprotect() is finalised.   The VMA must not

mm/mmap.c

+1 −5
Original line number Diff line number Diff line
@@ -3409,14 +3409,10 @@ static const char *special_mapping_name(struct vm_area_struct *vma) 
	return ((struct vm_special_mapping *)vma->vm_private_data)->name;

}



static int special_mapping_mremap(struct vm_area_struct *new_vma,

				  unsigned long flags)

static int special_mapping_mremap(struct vm_area_struct *new_vma)

{

	struct vm_special_mapping *sm = new_vma->vm_private_data;



	if (flags & MREMAP_DONTUNMAP)

		return -EINVAL;



	if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))

		return -EFAULT;

mm/mremap.c

+1 −1
Original line number Diff line number Diff line
@@ -545,7 +545,7 @@ static unsigned long move_vma(struct vm_area_struct *vma, 
	if (moved_len < old_len) {

		err = -ENOMEM;

	} else if (vma->vm_ops && vma->vm_ops->mremap) {

		err = vma->vm_ops->mremap(new_vma, flags);

		err = vma->vm_ops->mremap(new_vma);

	}



	if (unlikely(err)) {