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| author | Konstantin Khlebnikov <khlebnikov@openvz.org> | 2012-03-21 16:33:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-03-21 17:54:55 -0700 |
| commit | c3f0327f8e9d7a503f0d64573c311eddd61f197d (patch) | |
| tree | ebc59003d3bef08dd41d073eced2b53970e13662 | |
| parent | dc3f21eadeea6d9898271ff32d35d5e00c6872ea (diff) | |
| download | linux-c3f0327f8e9d7a503f0d64573c311eddd61f197d.tar.gz linux-c3f0327f8e9d7a503f0d64573c311eddd61f197d.tar.bz2 linux-c3f0327f8e9d7a503f0d64573c311eddd61f197d.zip | |
mm: add rss counters consistency check
Warn about non-zero rss counters at final mmdrop.
This check will prevent reoccurences of bugs such as that fixed in "mm:
fix rss count leakage during migration".
I didn't hide this check under CONFIG_VM_DEBUG because it rather small and
rss counters cover whole page-table management, so this is a good
invariant.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/fork.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index c4f38a849436..a9e99f3c18e0 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -511,6 +511,23 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) return NULL; } +static void check_mm(struct mm_struct *mm) +{ + int i; + + for (i = 0; i < NR_MM_COUNTERS; i++) { + long x = atomic_long_read(&mm->rss_stat.count[i]); + + if (unlikely(x)) + printk(KERN_ALERT "BUG: Bad rss-counter state " + "mm:%p idx:%d val:%ld\n", mm, i, x); + } + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + VM_BUG_ON(mm->pmd_huge_pte); +#endif +} + /* * Allocate and initialize an mm_struct. */ @@ -538,9 +555,7 @@ void __mmdrop(struct mm_struct *mm) mm_free_pgd(mm); destroy_context(mm); mmu_notifier_mm_destroy(mm); -#ifdef CONFIG_TRANSPARENT_HUGEPAGE - VM_BUG_ON(mm->pmd_huge_pte); -#endif + check_mm(mm); free_mm(mm); } EXPORT_SYMBOL_GPL(__mmdrop); |