nommu: yield CPU while disposing VM

commit 04c3496152394d17e3bc2316f9731ee3e8a026bc upstream.

Depending on processor speed, page size, and the amount of memory a
process is allowed to amass, cleanup of a large VM may freeze the system
for many seconds.  This can result in a watchdog timeout.

Make sure other tasks receive some service when cleaning up large VMs.

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Cc: Greg Ungerer <gerg@snapgear.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/mm/nommu.c b/mm/nommu.c
index ebb3154d84e40182e977cc938a3d2f8e344e6d79..406e8d47ce49f76180667647cffc717b029ff950 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1615,6 +1615,7 @@ void exit_mmap(struct mm_struct *mm)
                mm->mmap = vma->vm_next;
                delete_vma_from_mm(vma);
                delete_vma(mm, vma);
+               cond_resched();
        }
 
        kleave("");