On Mon, Apr 02, 2012 at 09:14:44PM +0400, Konstantin Khlebnikov wrote:
...
> >
> >Ah, it's about locking. I misundertand it at first.
> >Oleg, forget about my email then.
>
> Yes, it's about locking. Please review patch for your code from attachment.
Thanks a lot, Konstantin! This should do the trick.
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index cff94cd..4a41270 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -437,6 +437,7 @@ extern int get_dumpable(struct mm_struct *mm);
> /* leave room for more dump flags */
> #define MMF_VM_MERGEABLE 16 /* KSM may merge identical pages */
> #define MMF_VM_HUGEPAGE 17 /* set when VM_HUGEPAGE is set on vma */
> +#define MMF_EXE_FILE_CHANGED 18 /* see prctl(PR_SET_MM_EXE_FILE) */
>
> #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index da660f3..b217069 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -1714,17 +1714,11 @@ static bool vma_flags_mismatch(struct vm_area_struct *vma,
>
> static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
> {
> + struct vm_area_struct *vma;
> struct file *exe_file;
> struct dentry *dentry;
> int err;
>
> - /*
> - * Setting new mm::exe_file is only allowed when no VM_EXECUTABLE vma's
> - * remain. So perform a quick test first.
> - */
> - if (mm->num_exe_file_vmas)
> - return -EBUSY;
> -
> exe_file = fget(fd);
> if (!exe_file)
> return -EBADF;
> @@ -1745,17 +1739,28 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
> if (err)
> goto exit;
>
> + down_write(&mm->mmap_sem);
> + /*
> + * Forbid mm->exe_file change if there are mapped some other files.
> + */
> + err = -EEXIST;
> + for (vma = mm->mmap; vma; vma = vma->vm_next) {
> + if (vma->vm_file &&
> + !path_equal(&vma->vm_file->f_path, &exe_file->f_path))
> + goto out_unlock;
> + }
If I understand right, this snippet is emulating old behaviour (ie as
it was with num_exe_file_vmas), thus -EBUSY might be more appropriate?
But it's really a small nit I think. Thanks again.
Cyrill
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>