diff options
| author | Oleg Nesterov <oleg@tv-sign.ru> | 2008-07-25 01:47:38 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-07-25 10:53:39 -0700 |
| commit | 246bb0b1deb29726990620d8b5e55ca29f331362 (patch) | |
| tree | 5173b9e0c1d18934a8b2693c690a7162acb1bca8 /include | |
| parent | 7b34e4283c685f5cc6ba6d30e939906eee0d4bcf (diff) | |
kill PF_BORROWED_MM in favour of PF_KTHREAD
Kill PF_BORROWED_MM. Change use_mm/unuse_mm to not play with ->flags, and
do s/PF_BORROWED_MM/PF_KTHREAD/ for a couple of other users.
No functional changes yet. But this allows us to do further
fixes/cleanups.
oom_kill/ptrace/etc often check "p->mm != NULL" to filter out the
kthreads, this is wrong because of use_mm(). The problem with
PF_BORROWED_MM is that we need task_lock() to avoid races. With this
patch we can check PF_KTHREAD directly, or use a simple lockless helper:
/* The result must not be dereferenced !!! */
struct mm_struct *__get_task_mm(struct task_struct *tsk)
{
if (tsk->flags & PF_KTHREAD)
return NULL;
return tsk->mm;
}
Note also ecard_task(). It runs with ->mm != NULL, but it's the kernel
thread without PF_BORROWED_MM.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/sched.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index eec64a4adb9..0560999eb1d 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1483,7 +1483,6 @@ static inline void put_task_struct(struct task_struct *t) #define PF_EXITING 0x00000004 /* getting shut down */ #define PF_EXITPIDONE 0x00000008 /* pi exit done on shut down */ #define PF_VCPU 0x00000010 /* I'm a virtual CPU */ -#define PF_KTHREAD 0x00000020 /* I am a kernel thread */ #define PF_FORKNOEXEC 0x00000040 /* forked but didn't exec */ #define PF_SUPERPRIV 0x00000100 /* used super-user privileges */ #define PF_DUMPCORE 0x00000200 /* dumped core */ @@ -1497,7 +1496,7 @@ static inline void put_task_struct(struct task_struct *t) #define PF_KSWAPD 0x00040000 /* I am kswapd */ #define PF_SWAPOFF 0x00080000 /* I am in swapoff */ #define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */ -#define PF_BORROWED_MM 0x00200000 /* I am a kthread doing use_mm */ +#define PF_KTHREAD 0x00200000 /* I am a kernel thread */ #define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */ #define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */ #define PF_SPREAD_PAGE 0x01000000 /* Spread page cache over cpuset */ |