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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: Hugh Dickins <hugh@veritas.com> Acked-by: Eric Biederman <ebiederm@aristanetworks.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
parent
f520360d93
commit
095160aee9
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@ -241,9 +241,12 @@ static int bin_page_mkwrite(struct vm_area_struct *vma, struct page *page)
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struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
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int ret;
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if (!bb->vm_ops || !bb->vm_ops->page_mkwrite)
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if (!bb->vm_ops)
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return -EINVAL;
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if (!bb->vm_ops->page_mkwrite)
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return 0;
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if (!sysfs_get_active_two(attr_sd))
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return -EINVAL;
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@ -273,12 +276,78 @@ static int bin_access(struct vm_area_struct *vma, unsigned long addr,
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return ret;
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}
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#ifdef CONFIG_NUMA
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static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
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{
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struct file *file = vma->vm_file;
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struct bin_buffer *bb = file->private_data;
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struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
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int ret;
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if (!bb->vm_ops || !bb->vm_ops->set_policy)
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return 0;
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if (!sysfs_get_active_two(attr_sd))
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return -EINVAL;
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ret = bb->vm_ops->set_policy(vma, new);
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sysfs_put_active_two(attr_sd);
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return ret;
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}
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static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,
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unsigned long addr)
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{
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struct file *file = vma->vm_file;
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struct bin_buffer *bb = file->private_data;
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struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
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struct mempolicy *pol;
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if (!bb->vm_ops || !bb->vm_ops->get_policy)
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return vma->vm_policy;
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if (!sysfs_get_active_two(attr_sd))
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return vma->vm_policy;
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pol = bb->vm_ops->get_policy(vma, addr);
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sysfs_put_active_two(attr_sd);
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return pol;
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}
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static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
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const nodemask_t *to, unsigned long flags)
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{
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struct file *file = vma->vm_file;
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struct bin_buffer *bb = file->private_data;
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struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
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int ret;
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if (!bb->vm_ops || !bb->vm_ops->migrate)
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return 0;
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if (!sysfs_get_active_two(attr_sd))
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return 0;
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ret = bb->vm_ops->migrate(vma, from, to, flags);
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sysfs_put_active_two(attr_sd);
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return ret;
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}
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#endif
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static struct vm_operations_struct bin_vm_ops = {
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.open = bin_vma_open,
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.close = bin_vma_close,
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.fault = bin_fault,
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.page_mkwrite = bin_page_mkwrite,
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.access = bin_access,
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#ifdef CONFIG_NUMA
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.set_policy = bin_set_policy,
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.get_policy = bin_get_policy,
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.migrate = bin_migrate,
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#endif
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};
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static int mmap(struct file *file, struct vm_area_struct *vma)
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@ -287,7 +356,6 @@ static int mmap(struct file *file, struct vm_area_struct *vma)
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struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
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struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
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struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
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struct vm_operations_struct *vm_ops;
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int rc;
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mutex_lock(&bb->mutex);
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@ -302,24 +370,25 @@ static int mmap(struct file *file, struct vm_area_struct *vma)
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goto out_put;
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rc = attr->mmap(kobj, attr, vma);
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vm_ops = vma->vm_ops;
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vma->vm_ops = &bin_vm_ops;
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if (rc)
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goto out_put;
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/*
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* PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
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* to satisfy versions of X which crash if the mmap fails: that
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* substitutes a new vm_file, and we don't then want bin_vm_ops.
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*/
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if (vma->vm_file != file)
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goto out_put;
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rc = -EINVAL;
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if (bb->mmapped && bb->vm_ops != vma->vm_ops)
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goto out_put;
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#ifdef CONFIG_NUMA
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rc = -EINVAL;
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if (vm_ops && ((vm_ops->set_policy || vm_ops->get_policy || vm_ops->migrate)))
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goto out_put;
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#endif
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rc = 0;
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bb->mmapped = 1;
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bb->vm_ops = vm_ops;
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bb->vm_ops = vma->vm_ops;
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vma->vm_ops = &bin_vm_ops;
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out_put:
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sysfs_put_active_two(attr_sd);
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out_unlock:
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