On Wed, Apr 27, 2011 at 05:01, Andrea Righi wrote: > On Wed, Apr 27, 2011 at 10:14:53AM +1000, Dave Chinner wrote: >> On Tue, Apr 26, 2011 at 11:35:27PM +0200, Andrea Righi wrote: >> > This functionality can be used by all the applications that want to have a >> > better control over the page cache management (for example to immediately drop >> > pages that for sure will not be reused in the near future, without calling >> > posix_fadvise() for all the files they've touched), or to provide a more fine >> > grained debugging feature usable by the filesystem benchmarks. >> > >> > The system call does not require root privileges and it can be called by any >> > unprivileged application. For example, we can write a userspace tool to run >> > something like this: >> > >> > $ drop-pagecache /path/file_or_dir >> >> That's a potential DOS vector, I think. Drop the pagecache in a hard >> loop on the root fs of a busy server and watch it crawl... > > Yes, probably we could allow only the CAP_SYS_ADMIN tasks to execute > this syscall. if /proc/sys/vm/drop_caches has any checks other than file permission checks (i.e. UID==0), it'd probably be better to copy those rather than picking something different. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
