Messages in this thread | | | Date | Thu, 28 May 2015 07:57:11 -0400 (EDT) | From | Jan Stancek <> | Subject | Re: [PATCH 2/2] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline |
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----- Original Message ----- > From: "Alexey Dobriyan" <adobriyan@gmail.com> > To: akpm@linux-foundation.org > Cc: linux-kernel@vger.kernel.org, gorcunov@openvz.org, jarod@redhat.com, jstancek@redhat.com > Sent: Wednesday, 27 May, 2015 11:49:53 PM > Subject: [PATCH 2/2] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline > > /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. > > People noticed and ask questions: > http://stackoverflow.com/questions/199130/how-do-i-increase-the-proc-pid-cmdline-4096-byte-limit > > 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. > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> > Tested-by: Jarod Wilson <jarod@redhat.com> > Acked-by: Jarod Wilson <jarod@redhat.com> > --- > > v5: fix BUG_ON(env_start > env_end)
I can no longer trigger this BUG_ON() with v5 of the patch.
Regards, Jan
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