Messages in this thread | | | Date | Fri, 08 Jun 2012 17:29:04 +0400 | From | Konstantin Khlebnikov <> | Subject | Re: [patch 12/12] mm: correctly synchronize rss-counters at exit/exec |
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Oleg Nesterov wrote: > On 06/08, Konstantin Khlebnikov wrote: >> >> As result you can see "BUG: Bad rss-counter state mm:ffff88040783a680 idx:1 val:-1" in dmesg >> >> There left only one problem: nobody calls sync_mm_rss() after put_user() in mm_release(). > > Both callers call sync_mm_rss() to make check_mm() happy. But please > see the changelog, I think we should move it into mm_release(). See > the patch below (on top of v2 I sent). I need to recheck.
Patch below broken: it removes one hunk from kernel/exit.c twice. And it does not add anything into mm_release().
> > As for xacct_add_tsk(), yes it can "miss" that put_user(). But this > is what we have now, I think we do not care. > > Oleg. > > --- x/fs/exec.c > +++ x/fs/exec.c > @@ -822,7 +822,6 @@ static int exec_mmap(struct mm_struct *m > 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 > --- x/kernel/exit.c > +++ x/kernel/exit.c > @@ -656,7 +656,6 @@ static void exit_mm(struct task_struct * > if (!mm) > return; > > - sync_mm_rss(mm); > /* > * Serialize with any possible pending coredump. > * We must hold mmap_sem around checking core_state > --- x/kernel/taskstats.c > +++ x/kernel/taskstats.c > @@ -630,8 +630,7 @@ void taskstats_exit(struct task_struct * > if (!stats) > goto err; > > - if (tsk->mm) > - sync_mm_rss(tsk->mm); > + sync_mm_rss(tsk->mm); > fill_stats(tsk, stats); > > /* > --- x/kernel/exit.c > +++ x/kernel/exit.c > @@ -656,7 +656,6 @@ static void exit_mm(struct task_struct * > if (!mm) > return; > > - sync_mm_rss(mm); > /* > * Serialize with any possible pending coredump. > * We must hold mmap_sem around checking core_state >
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