The patch titled
mm: introduce get_mm_hiwater_xxx(), fix taskstats->hiwater_xxx accounting
has been added to the -mm tree. Its filename is
introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: mm: introduce get_mm_hiwater_xxx(), fix taskstats->hiwater_xxx accounting
From: Oleg Nesterov <oleg@xxxxxxxxxx>
xacct_add_tsk() relies on do_exit()->update_hiwater_xxx() and uses
mm->hiwater_xxx directly, this leads to 2 problems:
- taskstats_user_cmd() can call fill_pid()->xacct_add_tsk() at any
moment before the task exits, so we should check the current values of
rss/vm anyway.
- do_exit()->update_hiwater_xxx() calls are racy. An exiting thread can
be preempted right before mm->hiwater_xxx = new_val, and another thread
can use A_LOT of memory and exit in between. When the first thread
resumes it can be the last thread in the thread group, in that case we
report the wrong hiwater_xxx values which do not take A_LOT into
account.
Introduce get_mm_hiwater_rss() and get_mm_hiwater_vm() helpers and change
xacct_add_tsk() to use them. The first helper will also be used by
rusage->ru_maxrss accounting.
Kill do_exit()->update_hiwater_xxx() calls. Unless we are going to
decrease rss/vm there is no point to update mm->hiwater_xxx, and nobody
can look at this mm_struct when exit_mmap() actually unmaps the memory.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Hugh Dickins <hugh@xxxxxxxxxxx>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Acked-by: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sched.h | 3 +++
kernel/exit.c | 5 +----
kernel/tsacct.c | 4 ++--
mm/mmap.c | 2 +-
4 files changed, 7 insertions(+), 7 deletions(-)
diff -puN include/linux/sched.h~introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting include/linux/sched.h
--- a/include/linux/sched.h~introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting
+++ a/include/linux/sched.h
@@ -386,6 +386,9 @@ 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);
diff -puN kernel/exit.c~introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting kernel/exit.c
--- a/kernel/exit.c~introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting
+++ a/kernel/exit.c
@@ -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);
diff -puN kernel/tsacct.c~introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting kernel/tsacct.c
--- a/kernel/tsacct.c~introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting
+++ a/kernel/tsacct.c
@@ -92,8 +92,8 @@ 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;
diff -puN mm/mmap.c~introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting mm/mmap.c
--- a/mm/mmap.c~introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting
+++ a/mm/mmap.c
@@ -2102,7 +2102,7 @@ void exit_mmap(struct mm_struct *mm)
lru_add_drain();
flush_cache_mm(mm);
tlb = tlb_gather_mmu(mm, 1);
- /* Don't update_hiwater_rss(mm) here, do_exit already did */
+ /* update_hiwater_rss(mm) here? but nobody should be looking */
/* Use -1 here to ensure all VMAs in the mm are unmapped */
end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
vm_unacct_memory(nr_accounted);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
linux-next.patch
introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting.patch
forkc-cleanup-for-copy_sighand.patch
poll-allow-f_op-poll-to-sleep-take6.patch
workqueues-kill-cpu_singlethread_map-use-get_cpu_mask-instead.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
