On Thu, 12 Jul 2007 19:00:12 -0700 Matt Helsley <[EMAIL PROTECTED]> wrote:
> 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 <[EMAIL PROTECTED]> > --- > > 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. I wish we had a description of the bug which this fixes. That email of Chris's is referencing code which diddles with task_struct.exe_file, but your patch _adds_ task_struct.exe_file, so I am all confused. Your patch does lots of fput()s under task_lock(), but fput() can sleep. Plus what Al said. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
