linux-kernel - [RESEND] [PATCH] hugetlbfs: Do not call user_shm_lock() for MAP

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Date:	Wed, 23 Sep 2009 10:08:22 -0600
From:	Eric B Munson <emunson@...bm.net>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org, mel@....ul.ie,
	Eric B Munson <ebmunson@...ibm.com>
Subject: [RESEND] [PATCH] hugetlbfs: Do not call user_shm_lock() for MAP_HUGETLB fix

It seems I may have been having relay problems, I am resending this using
my personal account to make sure everyone that needs a copy gets one.

Andrew,

This patch seems to have slipped through the cracks during the discussion
on the MAP_HUGETLB flag, I am sorry for letting it slip.  Please fold this
into the indicated patch in -mm.

--- Cut here ---

The patch
hugetlbfs-allow-the-creation-of-files-suitable-for-map_private-on-the-vfs-internal-mount.patch
alters can_do_hugetlb_shm() to check if a file is being created for shared
memory or mmap(). If this returns false, we then unconditionally call
user_shm_lock() triggering a warning. This block should never be entered
for MAP_HUGETLB. This patch partially reverts the problem and fixes the check.

This patch should be considered a fix to
hugetlbfs-allow-the-creation-of-files-suitable-for-map_private-on-the-vfs-internal-mount.patch.

From: Mel Gorman <mel@....ul.ie>
Signed-off-by: Eric B Munson <ebmunson@...ibm.com>
---
 fs/hugetlbfs/inode.c |   12 +++---------
 1 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index e1a4ac4..0bf9d02 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -931,15 +931,9 @@ static struct file_system_type hugetlbfs_fs_type = {

 static struct vfsmount *hugetlbfs_vfsmount;

-static int can_do_hugetlb_shm(int creat_flags)
+static int can_do_hugetlb_shm(void)
 {
-	if (creat_flags != HUGETLBFS_SHMFS_INODE)
-		return 0;
-	if (capable(CAP_IPC_LOCK))
-		return 1;
-	if (in_group_p(sysctl_hugetlb_shm_group))
-		return 1;
-	return 0;
+	return capable(CAP_IPC_LOCK) || in_group_p(sysctl_hugetlb_shm_group);
 }

 struct file *hugetlb_file_setup(const char *name, size_t size, int acctflag,
@@ -955,7 +949,7 @@ struct file *hugetlb_file_setup(const char *name, size_t size, int acctflag,
 	if (!hugetlbfs_vfsmount)
 		return ERR_PTR(-ENOENT);

-	if (!can_do_hugetlb_shm(creat_flags)) {
+	if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
 		*user = current_user();
 		if (user_shm_lock(size, *user)) {
 			WARN_ONCE(1,
-- 
1.6.3.2

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