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authorLinus Torvalds <torvalds@linux-foundation.org>2012-06-07 17:54:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-06-07 17:54:07 -0700
commit48d212a2eecaca2e1875925837ad27b2f43f48a3 (patch)
treefbd83c7b15856971f6d7297e1d23dc862ba2989c /kernel/fork.c
parent46edaedaf3842164281d0f86c41bc152f4b4d32e (diff)
downloadop-kernel-dev-48d212a2eecaca2e1875925837ad27b2f43f48a3.zip
op-kernel-dev-48d212a2eecaca2e1875925837ad27b2f43f48a3.tar.gz
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/fork.c')
-rw-r--r--kernel/fork.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 0560781..ab5211b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -619,14 +619,6 @@ void mmput(struct mm_struct *mm)
module_put(mm->binfmt->module);
mmdrop(mm);
}
-
- /*
- * Final rss-counter synchronization. After this point there must be
- * no pagefaults into this mm from the current context. Otherwise
- * mm->rss_stat will be inconsistent.
- */
- if (mm)
- sync_mm_rss(mm);
}
EXPORT_SYMBOL_GPL(mmput);
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