Messages in this thread Patch in this message | | | Date | Thu, 31 May 2012 19:19:42 +0200 | From | Oleg Nesterov <> | Subject | [PATCH 1/2] correctly synchronize rss-counters at exit/exec |
| |
A simplified version of Konstantin Khlebnikov's patch.
do_exit() and exec_mmap() call sync_mm_rss() before mm_release() does put_user(clear_child_tid) which can update task->rss_stat and thus make mm->rss_stat inconsistent. This triggers the "BUG:" printk in check_mm().
- Move the final sync_mm_rss() from do_exit() to exit_mm(), and change exec_mmap() to call sync_mm_rss() after mm_release() to make check_mm() happy.
Perhaps we should simply move it into mm_release() and call it unconditionally to catch the "task->rss_stat != 0 && !task->mm" bugs.
- Since taskstats_exit() is called before exit_mm(), add another sync_mm_rss() into xacct_add_tsk() who actually uses rss_stat.
Probably we should also shift acct_update_integrals().
Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> Tested-by: Martin Mokrejs <mmokrejs@fold.natur.cuni.cz> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org> --- fs/exec.c | 2 +- kernel/exit.c | 5 ++--- kernel/tsacct.c | 1 + 3 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c index 52c9e2f..e49e3c2 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -823,10 +823,10 @@ static int exec_mmap(struct mm_struct *mm) /* 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 diff --git a/kernel/exit.c b/kernel/exit.c index ab972a7..b3a84b5 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -655,6 +655,8 @@ static void exit_mm(struct task_struct * tsk) 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 @@ -965,9 +967,6 @@ 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); diff --git a/kernel/tsacct.c b/kernel/tsacct.c index 23b4d78..a64ee90 100644 --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -91,6 +91,7 @@ void xacct_add_tsk(struct taskstats *stats, struct task_struct *p) 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; -- 1.5.5.1
| |