Oleg Nesterov wrote:
On 06/07, Konstantin Khlebnikov wrote:
Oleg Nesterov wrote:
I'll write the changelog and send the patch tomorrow.
Ding! Week is over, or I missed something? )
Pong ;)
I have sent the patch on May 31, see
http://marc.info/?l=linux-kernel&m=133848759505805
Also attached below, just in case.
Initiallly I sent 2 patches, see
http://marc.info/?l=linux-kernel&m=133848784705941
but 2/2 (your patch) was already merged.
Hmm, ok. Thanks.
I think rss-fix must be in stable-3.4.x -- that "BUG..." message can disturb users.
Plus via this bug any application can decrease rss down to zero =)
-------------------------------------------------------------------------------
[PATCH] 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@xxxxxxxxxxxxxxx>
Tested-by: Martin Mokrejs<mmokrejs@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Oleg Nesterov<oleg@xxxxxxxxxx>
Acked-by: Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>
---
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;
--
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