Commit 4b981bc1 authored by Hugh Dickins's avatar Hugh Dickins Committed by Andrew Morton
Browse files

kernfs: drop shared NUMA mempolicy hooks 

It seems strange that kernfs should be an outlier with a set_policy and
get_policy in its kernfs_vm_ops.  Ah, it dates back to v2.6.30's commit
095160ae ("sysfs: fix some bin_vm_ops errors"), when I had crashed on
powerpc's pci_mmap_legacy_page_range() fallback to shmem_zero_setup().

Well, that was commendably thorough, to give sysfs-bin a set_policy and
get_policy, just to avoid the way it was coded resulting in EINVAL from
mmap when CONFIG_NUMA; but somehow feels a bit over-the-top to me now.

It's easier to say that nobody should expect to manage a shmem object's
shared NUMA mempolicy via some kernfs backdoor to that object: delete that
code (and there's no longer an EINVAL from mmap in the NUMA case).

This then leaves set_policy/get_policy as implemented only by shmem -
though importantly also by SysV SHM, which has to interface with shmem
which implements them, and with SHM_HUGETLB which does not.

Link: https://lkml.kernel.org/r/302164-a760-4a9e-879b-6870c9b4013@google.com


Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Reviewed-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun heo <tj@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 10969b55

fs/kernfs/file.c

+0 −49
Original line number Diff line number Diff line
@@ -429,60 +429,11 @@ static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr, 
	return ret;

}



#ifdef CONFIG_NUMA

static int kernfs_vma_set_policy(struct vm_area_struct *vma,

				 struct mempolicy *new)

{

	struct file *file = vma->vm_file;

	struct kernfs_open_file *of = kernfs_of(file);

	int ret;



	if (!of->vm_ops)

		return 0;



	if (!kernfs_get_active(of->kn))

		return -EINVAL;



	ret = 0;

	if (of->vm_ops->set_policy)

		ret = of->vm_ops->set_policy(vma, new);



	kernfs_put_active(of->kn);

	return ret;

}



static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,

					       unsigned long addr)

{

	struct file *file = vma->vm_file;

	struct kernfs_open_file *of = kernfs_of(file);

	struct mempolicy *pol;



	if (!of->vm_ops)

		return vma->vm_policy;



	if (!kernfs_get_active(of->kn))

		return vma->vm_policy;



	pol = vma->vm_policy;

	if (of->vm_ops->get_policy)

		pol = of->vm_ops->get_policy(vma, addr);



	kernfs_put_active(of->kn);

	return pol;

}



#endif



static const struct vm_operations_struct kernfs_vm_ops = {

	.open		= kernfs_vma_open,

	.fault		= kernfs_vma_fault,

	.page_mkwrite	= kernfs_vma_page_mkwrite,

	.access		= kernfs_vma_access,

#ifdef CONFIG_NUMA

	.set_policy	= kernfs_vma_set_policy,

	.get_policy	= kernfs_vma_get_policy,

#endif

};



static int kernfs_fop_mmap(struct file *file, struct vm_area_struct *vma)