On Fri, 20 Mar 2015 20:51:47 +0300 Alexey Dobriyan <adobri...@gmail.com> wrote:
> /proc/$PID/cmdline truncates output at PAGE_SIZE. It is easy to see with > > $ cat /proc/self/cmdline $(seq 1037) 2>/dev/null > > However, command line size was never limited to PAGE_SIZE but to 128 KB and > relatively recently limitation was removed altogether. > > seq file interface is not OK, because it kmalloc's for whole output and > open + read(, 1) + sleep will pin arbitrary amounts of kernel memory. > To not do that, limit must be imposed which is incompatible with > arbitrary sized command lines. > > I apologize for hairy code, but this it direct consequence of command line > layout in memory and hacks to support things like "init [3]". > > The loops are "unrolled" otherwise it is either macros which hide > control flow or functions with 7-8 arguments with equal line count. > > There should be real setproctitle(2) or something. > > ... > > fs/proc/base.c | 203 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 194 insertions(+), 9 deletions(-) > I'm desperately trying to think of a reason to not merge this patch :( I haven't seen anyone complain about the PAGE_SIZE limit - can't we pretend we didn't notice? Or tell 'em to switch to powerpc so they get 64k! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
