> This patch avoids holding the mmap semaphore while walking VMAs in response to
> programs which read or follow the /proc/<pid|self>/exe symlink. This also allows
> us to merge mmu and nommu proc_exe_link() functions. The costs are holding the
> task lock, a separate reference to the executable file stored in the task
> struct, and increased code in fork, exec, and exit paths.
>
> Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
> ---
>
> Changelog:
>
> Hold task_lock() while using task->exe_file. With this change I haven't
> been able to reproduce Chris Wright's Oops report:
>
http://lkml.org/lkml/2007/5/31/34
> I used a 4-way, x86 system running kernbench. I also tried a 4-way x86_64
> system running pidof. I used oprofile during all runs but I could not
> reproduce Chris' Oops with the new patch.
>
> Compiled and passed simple tests for regressions when patched against a 2.6.20
> and a 2.6.22 kernel. Regression tests included a variety of file operations on
> /proc/<pid|self>/exe such as stat, lstat, open, close, readlink, and unlink. All
> produced the expected, baseline output results.
>
> Andrew, please consider this patch for inclusion in -mm.
