From: Roland McGrath <roland@redhat.com>

Date: Wed, 8 Sep 2010 02:36:28 +0000 (-0700)

Subject: execve: improve interactivity with large arguments

X-Git-Tag: v2.6.36-rc4~13

X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=7993bc1f4663c0db67bb8f0d98e6678145b387cd

execve: improve interactivity with large arguments

This adds a preemption point during the copying of the argument and

environment strings for execve, in copy_strings().  There is already

a preemption point in the count() loop, so this doesn't add any new

points in the abstract sense.

When the total argument+environment strings are very large, the time

spent copying them can be much more than a normal user time slice.

So this change improves the interactivity of the rest of the system

when one process is doing an execve with very large arguments.

Signed-off-by: Roland McGrath <roland@redhat.com>

Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

---

diff --git a/fs/exec.c b/fs/exec.c

index 1b63237..6f2d777 100644

--- a/fs/exec.c

+++ b/fs/exec.c

@@ -419,6 +419,8 @@ static int copy_strings(int argc, const char __user *const __user *argv,

 		while (len > 0) {

 			int offset, bytes_to_copy;

+			cond_resched();

+

 			offset = pos % PAGE_SIZE;

 			if (offset == 0)

 				offset = PAGE_SIZE;