Eric Lee / linux-smarc-t335x-v3.2

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Commit 6301cb95c119ebf324bb96ee226fa9ddffad80a7

Authored by Thomas Gleixner
1 parent a468d38934
Exists in master and in 4 other branches v3.2_AM335xPSP_04.06.00.11, v3.2_NEWT335xPSP_04.06.00.11, v3.2_SBC_SMARTMEN, v3.2_SMARCT335xPSP_04.06.00.11

sched: fix nr_uninterruptible accounting of frozen tasks really 

commit e3c8ca8336 (sched: do not count frozen tasks toward load) broke
the nr_uninterruptible accounting on freeze/thaw. On freeze the task
is excluded from accounting with a check for (task->flags &
PF_FROZEN), but that flag is cleared before the task is thawed. So
while we prevent that the task with state TASK_UNINTERRUPTIBLE
is accounted to nr_uninterruptible on freeze we decrement
nr_uninterruptible on thaw.

Use a separate flag which is handled by the freezing task itself. Set
it before calling the scheduler with TASK_UNINTERRUPTIBLE state and
clear it after we return from frozen state.

Cc: <stable@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Showing 2 changed files with 9 additions and 1 deletions Side-by-side Diff

include/linux/sched.h
Diff comments   View file @ 6301cb9
... ... @@ -209,7 +209,7 @@
209 209 ((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0)
210 210 #define task_contributes_to_load(task) \
211 211 ((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
212   - (task->flags & PF_FROZEN) == 0)
  212 + (task->flags & PF_FREEZING) == 0)
213 213  
214 214 #define __set_task_state(tsk, state_value) \
215 215 do { (tsk)->state = (state_value); } while (0)
... ... @@ -1680,6 +1680,7 @@
1680 1680 #define PF_MEMALLOC 0x00000800 /* Allocating memory */
1681 1681 #define PF_FLUSHER 0x00001000 /* responsible for disk writeback */
1682 1682 #define PF_USED_MATH 0x00002000 /* if unset the fpu must be initialized before use */
  1683 +#define PF_FREEZING 0x00004000 /* freeze in progress. do not account to load */
1683 1684 #define PF_NOFREEZE 0x00008000 /* this thread should not be frozen */
1684 1685 #define PF_FROZEN 0x00010000 /* frozen for system suspend */
1685 1686 #define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */
... ... @@ -44,12 +44,19 @@
44 44 recalc_sigpending(); /* We sent fake signal, clean it up */
45 45 spin_unlock_irq(&current->sighand->siglock);
46 46  
  47 + /* prevent accounting of that task to load */
  48 + current->flags |= PF_FREEZING;
  49 +
47 50 for (;;) {
48 51 set_current_state(TASK_UNINTERRUPTIBLE);
49 52 if (!frozen(current))
50 53 break;
51 54 schedule();
52 55 }
  56 +
  57 + /* Remove the accounting blocker */
  58 + current->flags &= ~PF_FREEZING;
  59 +
53 60 pr_debug("%s left refrigerator\n", current->comm);
54 61 __set_current_state(save);
55 62 }