linux-kernel - [PATCH 4/4] uprobes: __replace_page() needs munlock_vma

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Message-ID: <20120712171025.GA25510@redhat.com>
Date:	Thu, 12 Jul 2012 19:10:25 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] uprobes: __replace_page() needs munlock_vma_page()

Like do_wp_page(), __replace_page() should do munlock_vma_page()
for the case when the old page still has other !VM_LOCKED mappings.
Unfortunately this needs mm/internal.h.

Also, move put_page() outside of ptl lock. This doesn't really
matter but looks a bit better.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index fc1df43..aeea41b 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -32,6 +32,7 @@
 #include <linux/swap.h>		/* try_to_free_swap */
 #include <linux/ptrace.h>	/* user_enable_single_step */
 #include <linux/kdebug.h>	/* notifier mechanism */
+#include "../../mm/internal.h"	/* munlock_vma_page */
 
 #include <linux/uprobes.h>
 
@@ -141,7 +142,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 	pte_t *ptep;
 	int err;
 
-	/* freeze PageSwapCache() for try_to_free_swap() below */
+	/* For try_to_free_swap() and munlock_vma_page() below */
 	lock_page(page);
 
 	err = -EAGAIN;
@@ -164,9 +165,12 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 	page_remove_rmap(page);
 	if (!page_mapped(page))
 		try_to_free_swap(page);
-	put_page(page);
 	pte_unmap_unlock(ptep, ptl);
 
+	if (vma->vm_flags & VM_LOCKED)
+		munlock_vma_page(page);
+	put_page(page);
+
 	err = 0;
  unlock:
 	unlock_page(page);
-- 
1.5.5.1

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