AcoSail/kernel_optimize_test
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uml: activate_mm: remove the dead PF_BORROWED_MM check

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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: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2008-06-06 11:31:39 -07:00 committed by Linus Torvalds
parent 06a1578e24
commit aab2545fdd
2 changed files with 3 additions and 13 deletions
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4
fs/aio.c
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@ -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);

12
include/asm-um/mmu_context.h
View File

@ -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);
__switch_mm(&new->context.id);
arch_dup_mmap(old, new);
}