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Commit 2584e517 authored by Ravikiran G Thirumalai's avatar Ravikiran G Thirumalai Committed by Linus Torvalds
Browse files

mm: reintroduce and deprecate rlimit based access for SHM_HUGETLB 



Allow non root users with sufficient mlock rlimits to be able to allocate
hugetlb backed shm for now.  Deprecate this though.  This is being
deprecated because the mlock based rlimit checks for SHM_HUGETLB is not
consistent with mmap based huge page allocations.

Signed-off-by: default avatarRavikiran Thirumalai <kiran@scalex86.org>
Reviewed-by: default avatarMel Gorman <mel@csn.ul.ie>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8a0bdec1

Documentation/feature-removal-schedule.txt

+12 −0
Original line number Diff line number Diff line
@@ -311,6 +311,18 @@ Who: Vlad Yasevich <vladislav.yasevich@hp.com> 


---------------------------



What:	Ability for non root users to shm_get hugetlb pages based on mlock

	resource limits

When:	2.6.31

Why:	Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or

	have CAP_IPC_LOCK to be able to allocate shm segments backed by

	huge pages.  The mlock based rlimit check to allow shm hugetlb is

	inconsistent with mmap based allocations.  Hence it is being

	deprecated.

Who:	Ravikiran Thirumalai <kiran@scalex86.org>



---------------------------



What:	CONFIG_THERMAL_HWMON

When:	January 2009

Why:	This option was introduced just to allow older lm-sensors userspace

fs/hugetlbfs/inode.c

+11 −2
Original line number Diff line number Diff line
@@ -949,6 +949,7 @@ static int can_do_hugetlb_shm(void) 
struct file *hugetlb_file_setup(const char *name, size_t size, int acctflag)

{

	int error = -ENOMEM;

	int unlock_shm = 0;

	struct file *file;

	struct inode *inode;

	struct dentry *dentry, *root;
@@ -958,8 +959,14 @@ 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())

	if (!can_do_hugetlb_shm()) {

		if (user_shm_lock(size, user)) {

			unlock_shm = 1;

			WARN_ONCE(1,

			  "Using mlock ulimits for SHM_HUGETLB deprecated\n");

		} else

			return ERR_PTR(-EPERM);

	}



	root = hugetlbfs_vfsmount->mnt_root;

	quick_string.name = name;
@@ -999,6 +1006,8 @@ struct file *hugetlb_file_setup(const char *name, size_t size, int acctflag) 
out_dentry:

	dput(dentry);

out_shm_unlock:

	if (unlock_shm)

		user_shm_unlock(size, user);

	return ERR_PTR(error);

}