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mm: reintroduce and deprecate rlimit based access for SHM_HUGETLB

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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: 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>
This commit is contained in:
Ravikiran G Thirumalai 2009-03-31 15:21:26 -07:00 committed by Linus Torvalds
parent 8a0bdec194
commit 2584e51732
2 changed files with 23 additions and 2 deletions
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12
Documentation/feature-removal-schedule.txt
View file

@ -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

13
fs/hugetlbfs/inode.c
View file

@ -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())
return ERR_PTR(-EPERM);
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 @@ out_inode:
out_dentry:
dput(dentry);
out_shm_unlock:
if (unlock_shm)
user_shm_unlock(size, user);
return ERR_PTR(error);
}