On Thu, Jun 04, 2015 at 09:06:10PM +0530, Navin P wrote: > On Thu, Jun 4, 2015 at 1:34 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > On Thu, Jun 04, 2015 at 01:11:48PM +0530, Navin P wrote: > >> On Thu, Jun 4, 2015 at 10:47 AM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > >> > On Thu, Jun 04, 2015 at 09:52:08AM +0530, Navin P wrote: > >> >> Hi, > >> >> > >> >> I want to change the cmdline of a process to support 8096 . It works > >> >> well on ppc where the page size is 65k. > >> >> But when i try to increase it on x86 (i686) > >> >> > >> >> http://lxr.free-electrons.com/source/fs/proc/base.c by doing > >> >> 6*PAGE_SIZE, i get kernel panic after some time > >> >> > >> >> 199 static int proc_pid_cmdline(struct seq_file *m, struct pid_namespace *ns, > >> >> 200 struct pid *pid, struct task_struct *task) > >> >> 201 { > >> >> 202 /* > >> >> 203 * Rely on struct seq_operations::show() being called once > >> >> 204 * per internal buffer allocation. See single_open(), traverse(). > >> >> 205 */ > >> >> 206 BUG_ON(m->size < PAGE_SIZE); > >> >> 207 m->count += get_cmdline(task, m->buf, 6*PAGE_SIZE); > >> >> 208 return 0; > >> >> 209 } > >> >> 210 > >> > > >> > That shows you that this will not work, sorry. > >> > >> Can you please help me and guide me into achieving this ? > > > > Why do you want this? What problem are you trying to solve that you > > have come to the conclusion that increasing the size of the command line > > is the solution? > > > I'm trying to learn things so that default cmd linux across all > distributions for ia64 and ppc which has PAGE_SIZE has 64k works . We > have this 3rd party application with deeply mounted dir that runs as a > testcase more than 5k chars . Applications shouldn't be messing around with the kernel command line. > We can change it , i thought if that was > the problem ? So just trying to learn. I tried changing the PAGE_SHIFT > but that made the kernel non-bootable or stuck at booting. You can not easily, if at all, change the PAGE_SIZE of an architecture. That is a non-trivial task that takes a ton of knowledge about the platform. > This panics only when you access the pid with more than 4k chars. A pid is a number, not a string. What do you mean by "pid" in this context? greg k-h _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
