Re: 3.4-rc7: BUG: Bad rss-counter state mm:ffff88040b56f800 idx:1val:-59

From: Oleg Nesterov
Date: Wed May 23 2012 - 13:23:42 EST


On 05/22, Andrew Morton wrote:
>
> Also, I have a note here that Oleg was unhappy with the patch. Oleg
> happiness is important. Has he cheered up yet?

Well, yes, I do not really like this patch ;) Because I think there is
a more simple/straightforward fix, see below. In my opinion it also
makes the original code simpler.

But. Obviously this is subjective, I can't prove my patch is "better",
and I didn't try to test it.

So I won't argue with Konstantin who dislikes my patch, although I
would like to know the reason.

Oleg.


--- a/kernel/tsacct.c
+++ b/kernel/tsacct.c
@@ -91,6 +91,7 @@ void xacct_add_tsk(struct taskstats *sta
stats->virtmem = p->acct_vm_mem1 * PAGE_SIZE / MB;
mm = get_task_mm(p);
if (mm) {
+ sync_mm_rss(mm);
/* adjust to KB unit */
stats->hiwater_rss = get_mm_hiwater_rss(mm) * PAGE_SIZE / KB;
stats->hiwater_vm = get_mm_hiwater_vm(mm) * PAGE_SIZE / KB;
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -643,6 +643,8 @@ static void exit_mm(struct task_struct *
mm_release(tsk, mm);
if (!mm)
return;
+
+ sync_mm_rss(mm);
/*
* Serialize with any possible pending coredump.
* We must hold mmap_sem around checking core_state
@@ -960,9 +962,6 @@ void do_exit(long code)
preempt_count());

acct_update_integrals(tsk);
- /* sync mm's RSS info before statistics gathering */
- if (tsk->mm)
- sync_mm_rss(tsk->mm);
group_dead = atomic_dec_and_test(&tsk->signal->live);
if (group_dead) {
hrtimer_cancel(&tsk->signal->real_timer);
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -823,10 +823,10 @@ static int exec_mmap(struct mm_struct *m
/* Notify parent that we're no longer interested in the old VM */
tsk = current;
old_mm = current->mm;
- sync_mm_rss(old_mm);
mm_release(tsk, old_mm);

if (old_mm) {
+ sync_mm_rss(old_mm);
/*
* Make sure that if there is a core dump in progress
* for the old mm, we get out and die instead of going


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