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Commit 095160ae authored by Hugh Dickins's avatar Hugh Dickins Committed by Greg Kroah-Hartman
Browse files

sysfs: fix some bin_vm_ops errors 



Commit 86c9508eb1c0ce5aa07b5cf1d36b60c54efc3d7a
"sysfs: don't block indefinitely for unmapped files" in linux-next
crashes the PowerMac G5 when X starts up.  It's caught out by the way
powerpc's pci_mmap of legacy_mem uses shmem_zero_setup(), substituting
a new vma->vm_file whose private_data no longer points to the bin_buffer
(substitution done because some versions of X crash if that mmap fails).

The fix to this is straightforward: the original vm_file is fput() in
that case, so this mmap won't block sysfs at all, so just don't switch
over to bin_vm_ops if vm_file has changed.

But more fixes made before realizing that was the problem:-

It should not be an error if bin_page_mkwrite() finds no underlying
page_mkwrite().

Check that a file already mmap'ed has the same underlying vm_ops
_before_ pointing vma->vm_ops at bin_vm_ops.

If the file being mmap'ed is a shmem/tmpfs file, don't fail the mmap
on CONFIG_NUMA=y, just because that has a set_policy and get_policy:
provide bin_set_policy, bin_get_policy and bin_migrate.

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Acked-by: default avatarEric Biederman <ebiederm@aristanetworks.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent f520360d

fs/sysfs/bin.c

+79 −10
Original line number Diff line number Diff line
@@ -241,9 +241,12 @@ static int bin_page_mkwrite(struct vm_area_struct *vma, struct page *page) 
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;

	int ret;



	if (!bb->vm_ops || !bb->vm_ops->page_mkwrite)

	if (!bb->vm_ops)

		return -EINVAL;



	if (!bb->vm_ops->page_mkwrite)

		return 0;



	if (!sysfs_get_active_two(attr_sd))

		return -EINVAL;
@@ -273,12 +276,78 @@ static int bin_access(struct vm_area_struct *vma, unsigned long addr, 
	return ret;

}



#ifdef CONFIG_NUMA

static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)

{

	struct file *file = vma->vm_file;

	struct bin_buffer *bb = file->private_data;

	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;

	int ret;



	if (!bb->vm_ops || !bb->vm_ops->set_policy)

		return 0;



	if (!sysfs_get_active_two(attr_sd))

		return -EINVAL;



	ret = bb->vm_ops->set_policy(vma, new);



	sysfs_put_active_two(attr_sd);

	return ret;

}



static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,

					unsigned long addr)

{

	struct file *file = vma->vm_file;

	struct bin_buffer *bb = file->private_data;

	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;

	struct mempolicy *pol;



	if (!bb->vm_ops || !bb->vm_ops->get_policy)

		return vma->vm_policy;



	if (!sysfs_get_active_two(attr_sd))

		return vma->vm_policy;



	pol = bb->vm_ops->get_policy(vma, addr);



	sysfs_put_active_two(attr_sd);

	return pol;

}



static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,

			const nodemask_t *to, unsigned long flags)

{

	struct file *file = vma->vm_file;

	struct bin_buffer *bb = file->private_data;

	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;

	int ret;



	if (!bb->vm_ops || !bb->vm_ops->migrate)

		return 0;



	if (!sysfs_get_active_two(attr_sd))

		return 0;



	ret = bb->vm_ops->migrate(vma, from, to, flags);



	sysfs_put_active_two(attr_sd);

	return ret;

}

#endif



static struct vm_operations_struct bin_vm_ops = {

	.open		= bin_vma_open,

	.close		= bin_vma_close,

	.fault		= bin_fault,

	.page_mkwrite	= bin_page_mkwrite,

	.access		= bin_access,

#ifdef CONFIG_NUMA

	.set_policy	= bin_set_policy,

	.get_policy	= bin_get_policy,

	.migrate	= bin_migrate,

#endif

};



static int mmap(struct file *file, struct vm_area_struct *vma)
@@ -287,7 +356,6 @@ static int mmap(struct file *file, struct vm_area_struct *vma) 
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;

	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;

	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;

	struct vm_operations_struct *vm_ops;

	int rc;



	mutex_lock(&bb->mutex);
@@ -302,24 +370,25 @@ static int mmap(struct file *file, struct vm_area_struct *vma) 
		goto out_put;



	rc = attr->mmap(kobj, attr, vma);

	vm_ops = vma->vm_ops;

	vma->vm_ops = &bin_vm_ops;

	if (rc)

		goto out_put;



	rc = -EINVAL;

	if (bb->mmapped && bb->vm_ops != vma->vm_ops)

	/*

	 * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()

	 * to satisfy versions of X which crash if the mmap fails: that

	 * substitutes a new vm_file, and we don't then want bin_vm_ops.

	 */

	if (vma->vm_file != file)

		goto out_put;



#ifdef CONFIG_NUMA

	rc = -EINVAL;

	if (vm_ops && ((vm_ops->set_policy || vm_ops->get_policy || vm_ops->migrate)))

	if (bb->mmapped && bb->vm_ops != vma->vm_ops)

		goto out_put;

#endif



	rc = 0;

	bb->mmapped = 1;

	bb->vm_ops = vm_ops;

	bb->vm_ops = vma->vm_ops;

	vma->vm_ops = &bin_vm_ops;

out_put:

	sysfs_put_active_two(attr_sd);

out_unlock: