linux-kernel - [tip:perfcounters/core] perf_counter: fix the mlock accounting

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Date:	Tue, 7 Apr 2009 09:08:01 GMT
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, paulus@...ba.org, hpa@...or.com,
	mingo@...hat.com, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
	cjashfor@...ux.vnet.ibm.com, mingo@...e.hu
Subject: [tip:perfcounters/core] perf_counter: fix the mlock accounting

Commit-ID:  ebb3c4c4cb81d64cc041356915ec015e2c57092a
Gitweb:     http://git.kernel.org/tip/ebb3c4c4cb81d64cc041356915ec015e2c57092a
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Mon, 6 Apr 2009 11:45:05 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Tue, 7 Apr 2009 10:48:57 +0200

perf_counter: fix the mlock accounting

Reading through the code I saw I forgot the finish the mlock accounting.
Do so now.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
LKML-Reference: <20090406094517.899767331@...llo.nl>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 kernel/perf_counter.c |   33 +++++++++++++++++++++------------
 1 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 195e976..c841563 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1461,13 +1461,14 @@ static void perf_mmap_close(struct vm_area_struct *vma)
 
 	if (atomic_dec_and_mutex_lock(&counter->mmap_count,
 				      &counter->mmap_mutex)) {
+		vma->vm_mm->locked_vm -= counter->data->nr_pages + 1;
 		perf_mmap_data_free(counter);
 		mutex_unlock(&counter->mmap_mutex);
 	}
 }
 
 static struct vm_operations_struct perf_mmap_vmops = {
-	.open = perf_mmap_open,
+	.open  = perf_mmap_open,
 	.close = perf_mmap_close,
 	.fault = perf_mmap_fault,
 };
@@ -1499,24 +1500,32 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 	if (vma->vm_pgoff != 0)
 		return -EINVAL;
 
-	locked = vma_size >>  PAGE_SHIFT;
-	locked += vma->vm_mm->locked_vm;
+	mutex_lock(&counter->mmap_mutex);
+	if (atomic_inc_not_zero(&counter->mmap_count)) {
+		if (nr_pages != counter->data->nr_pages)
+			ret = -EINVAL;
+		goto unlock;
+	}
+
+	locked = vma->vm_mm->locked_vm;
+	locked += nr_pages + 1;
 
 	lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
 	lock_limit >>= PAGE_SHIFT;
 
-	if ((locked > lock_limit) && !capable(CAP_IPC_LOCK))
-		return -EPERM;
-
-	mutex_lock(&counter->mmap_mutex);
-	if (atomic_inc_not_zero(&counter->mmap_count))
-		goto out;
+	if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
+		ret = -EPERM;
+		goto unlock;
+	}
 
 	WARN_ON(counter->data);
 	ret = perf_mmap_data_alloc(counter, nr_pages);
-	if (!ret)
-		atomic_set(&counter->mmap_count, 1);
-out:
+	if (ret)
+		goto unlock;
+
+	atomic_set(&counter->mmap_count, 1);
+	vma->vm_mm->locked_vm += nr_pages + 1;
+unlock:
 	mutex_unlock(&counter->mmap_mutex);
 
 	vma->vm_flags &= ~VM_MAYWRITE;
--
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