[101/103] execve: improve interactivity with large arguments

[Greg KH]

2.6.35-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Roland McGrath <roland@xxxxxxxxxx>

commit 7993bc1f4663c0db67bb8f0d98e6678145b387cd upstream.

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@xxxxxxxxxx>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Chuck Ebbert <cebbert@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/exec.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -420,6 +420,8 @@ static int copy_strings(int argc, char _
 		while (len > 0) {
 			int offset, bytes_to_copy;
 
+			cond_resched();
+
 			offset = pos % PAGE_SIZE;
 			if (offset == 0)
 				offset = PAGE_SIZE;


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