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Commit aab2545f authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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uml: activate_mm: remove the dead PF_BORROWED_MM check 



use_mm() was changed to use switch_mm() instead of activate_mm(), since
then nobody calls (and nobody should call) activate_mm() with
PF_BORROWED_MM bit set.

As Jeff Dike pointed out, we can also remove the "old != new" check, it is
always true.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 06a1578e

fs/aio.c

+0 −4
Original line number Diff line number Diff line
@@ -591,10 +591,6 @@ static void use_mm(struct mm_struct *mm) 
	atomic_inc(&mm->mm_count);

	tsk->mm = mm;

	tsk->active_mm = mm;

	/*

	 * Note that on UML this *requires* PF_BORROWED_MM to be set, otherwise

	 * it won't work. Update it accordingly if you change it here

	 */

	switch_mm(active_mm, mm, tsk);

	task_unlock(tsk);

include/asm-um/mmu_context.h

+3 −9
Original line number Diff line number Diff line
@@ -22,16 +22,10 @@ extern void force_flush_all(void); 
static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)

{

	/*

	 * This is called by fs/exec.c and fs/aio.c. In the first case, for an

	 * exec, we don't need to do anything as we're called from userspace

	 * and thus going to use a new host PID. In the second, we're called

	 * from a kernel thread, and thus need to go doing the mmap's on the

	 * host. Since they're very expensive, we want to avoid that as far as

	 * possible.

	 * This is called by fs/exec.c and sys_unshare()

	 * when the new ->mm is used for the first time.

	 */

	if (old != new && (current->flags & PF_BORROWED_MM))

	__switch_mm(&new->context.id);



	arch_dup_mmap(old, new);

}