Commit 8a0bdec1 authored Mar 31, 2009 by Ravikiran G Thirumalai Committed by Linus Torvalds Apr 01, 2009

mm: fix SHM_HUGETLB to work with users in hugetlb_shm_group



Fix hugetlb subsystem so that non root users belonging to
hugetlb_shm_group can actually allocate hugetlb backed shm.

Currently non root users cannot even map one large page using SHM_HUGETLB
when they belong to the gid in /proc/sys/vm/hugetlb_shm_group.  This is
because allocation size is verified against RLIMIT_MEMLOCK resource limit
even if the user belongs to hugetlb_shm_group.

This patch
1. Fixes hugetlb subsystem so that users with CAP_IPC_LOCK and users
   belonging to hugetlb_shm_group don't need to be restricted with
   RLIMIT_MEMLOCK resource limits
2. This patch also disables mlock based rlimit checking (which will
   be reinstated and marked deprecated in a subsequent patch).

Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Reviewed-by: Mel Gorman <mel@csn.ul.ie>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent e3a7cca1

fs/hugetlbfs/inode.c

+1 −7

Original line number	Diff line number	Diff line
		@@ -943,9 +943,7 @@ static struct vfsmount *hugetlbfs_vfsmount;

		static int can_do_hugetlb_shm(void)
		{
		return likely(capable(CAP_IPC_LOCK) \|\|
		in_group_p(sysctl_hugetlb_shm_group) \|\|
		can_do_mlock());
		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)
		@@ -963,9 +961,6 @@ struct file hugetlb_file_setup(const char name, size_t size, int acctflag)
		if (!can_do_hugetlb_shm())
		return ERR_PTR(-EPERM);

		if (!user_shm_lock(size, user))
		return ERR_PTR(-ENOMEM);

		root = hugetlbfs_vfsmount->mnt_root;
		quick_string.name = name;
		quick_string.len = strlen(quick_string.name);
		@@ -1004,7 +999,6 @@ out_inode:
		out_dentry:
		dput(dentry);
		out_shm_unlock:
		user_shm_unlock(size, user);
		return ERR_PTR(error);
		}

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