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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-06-07 17:54:07 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-06-07 17:54:07 -0700 |
| commit | 48d212a2eecaca2e1875925837ad27b2f43f48a3 (patch) | |
| tree | fbd83c7b15856971f6d7297e1d23dc862ba2989c /kernel/exit.c | |
| parent | 46edaedaf3842164281d0f86c41bc152f4b4d32e (diff) | |
| download | linux-48d212a2eecaca2e1875925837ad27b2f43f48a3.tar.bz2 | |
Revert "mm: correctly synchronize rss-counters at exit/exec"
This reverts commit 40af1bbdca47e5c8a2044039bb78ca8fd8b20f94.
It's horribly and utterly broken for at least the following reasons:
- calling sync_mm_rss() from mmput() is fundamentally wrong, because
there's absolutely no reason to believe that the task that does the
mmput() always does it on its own VM. Example: fork, ptrace, /proc -
you name it.
- calling it *after* having done mmdrop() on it is doubly insane, since
the mm struct may well be gone now.
- testing mm against NULL before you call it is insane too, since a
NULL mm there would have caused oopses long before.
.. and those are just the three bugs I found before I decided to give up
looking for me and revert it asap. I should have caught it before I
even took it, but I trusted Andrew too much.
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/exit.c')
| -rw-r--r-- | kernel/exit.c | 13 |
1 files changed, 5 insertions, 8 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 804fb6bb8161..34867cc5b42a 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -423,7 +423,6 @@ void daemonize(const char *name, ...) * user space pages. We don't need them, and if we didn't close them * they would be locked into memory. */ - mm_release(current, current->mm); exit_mm(current); /* * We don't want to get frozen, in case system-wide hibernation @@ -641,6 +640,7 @@ static void exit_mm(struct task_struct * tsk) struct mm_struct *mm = tsk->mm; struct core_state *core_state; + mm_release(tsk, mm); if (!mm) return; /* @@ -960,13 +960,9 @@ void do_exit(long code) preempt_count()); acct_update_integrals(tsk); - - /* Set exit_code before complete_vfork_done() in mm_release() */ - tsk->exit_code = code; - - /* Release mm and sync mm's RSS info before statistics gathering */ - mm_release(tsk, tsk->mm); - + /* 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); @@ -979,6 +975,7 @@ void do_exit(long code) tty_audit_exit(); audit_free(tsk); + tsk->exit_code = code; taskstats_exit(tsk, group_dead); exit_mm(tsk); |