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Message-ID: <20081203181220.GA22918@redhat.com>
Date: Wed, 3 Dec 2008 19:12:20 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Balbir Singh <balbir@...ux.vnet.ibm.com>,
Hugh Dickins <hugh@...itas.com>, Jay Lan <jlan@....com>,
Jiri Pirko <jpirko@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] introduce get_mm_hiwater_xxx(), fix taskstats->hiwater_xxx
accounting
Unless we are going to decrease rss/vm there is no point to call the
(racy) update_hiwater_xxx() helpers. Still do_exit() does this, and
the accounting code uses mm->hiwater_xxx directly.
This is not right. fill_pid()->xacct_add_tsk() can be called by
taskstats_user_cmd() at any time, not only when the task exits.
in that case taskstats->hiwater_xxx can be very wrong.
Introduce get_mm_hiwater_rss() and get_mm_hiwater_vm() to use instead,
and kill the "if (tsk->mm) {}" code in do_exit(). The first helper will
be also used to actually fill/report rusage->ru_maxrss.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
--- K-28/include/linux/sched.h~HIWATER 2008-12-02 17:12:40.000000000 +0100
+++ K-28/include/linux/sched.h 2008-12-03 18:17:18.000000000 +0100
@@ -388,6 +388,9 @@ extern void arch_unmap_area_topdown(stru
(mm)->hiwater_vm = (mm)->total_vm; \
} while (0)
+#define get_mm_hiwater_rss(mm) max((mm)->hiwater_rss, get_mm_rss(mm))
+#define get_mm_hiwater_vm(mm) max((mm)->hiwater_vm, (mm)->total_vm)
+
extern void set_dumpable(struct mm_struct *mm, int value);
extern int get_dumpable(struct mm_struct *mm);
--- K-28/kernel/tsacct.c~HIWATER 2008-10-10 00:13:53.000000000 +0200
+++ K-28/kernel/tsacct.c 2008-12-03 18:24:28.000000000 +0100
@@ -90,8 +90,8 @@ void xacct_add_tsk(struct taskstats *sta
mm = get_task_mm(p);
if (mm) {
/* adjust to KB unit */
- stats->hiwater_rss = mm->hiwater_rss * PAGE_SIZE / KB;
- stats->hiwater_vm = mm->hiwater_vm * PAGE_SIZE / KB;
+ stats->hiwater_rss = get_mm_hiwater_rss(mm) * PAGE_SIZE / KB;
+ stats->hiwater_vm = get_mm_hiwater_vm(mm) * PAGE_SIZE / KB;
mmput(mm);
}
stats->read_char = p->ioac.rchar;
--- K-28/kernel/exit.c~HIWATER 2008-12-02 17:12:40.000000000 +0100
+++ K-28/kernel/exit.c 2008-12-03 18:21:06.000000000 +0100
@@ -1048,10 +1048,7 @@ NORET_TYPE void do_exit(long code)
preempt_count());
acct_update_integrals(tsk);
- if (tsk->mm) {
- update_hiwater_rss(tsk->mm);
- update_hiwater_vm(tsk->mm);
- }
+
group_dead = atomic_dec_and_test(&tsk->signal->live);
if (group_dead) {
hrtimer_cancel(&tsk->signal->real_timer);
--
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