From 095160aee954688a9bad225952c4bee546541e19 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 23 Mar 2009 01:41:27 +0000 Subject: [PATCH] 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 Acked-by: Eric Biederman Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/bin.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 79 insertions(+), 10 deletions(-) diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c index 96cc2bf6a84..07703d3ff4a 100644 --- a/fs/sysfs/bin.c +++ b/fs/sysfs/bin.c @@ -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: -- 2.11.4.GIT