tree 17c746035cf727bc5494b9116ae6034724aaede3
parent 644fd4f5de9ca147daeb6dc5f844b44ec3d58b47
author Pavel Emelianov <xemul@sw.ru> 1178609350 -0700
committer Linus Torvalds <torvalds@woody.linux-foundation.org> 1178648109 -0700

Lockdep treats down_write_trylock like regular down_write

This causes constructions like

down_write(&mm1->mmap_sem);
if (down_write_trylock(&mm2->mmap_sem)) {
       ...
       up_write(&mm2->mmap_sem);
}
up_write(&mm1->mmap_sem);

generate a lockdep warning about circular locking dependence.

Call rwsem_acquire() with trylock set to 1.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>